Pharmacology

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Assistant Professor: Ashraf Saddieak Alias
 Contents
N Titles Page
1 Introduction to Pharmacology 3
2 Application of Pharmacology in 5
nursing practice
3 Basic principles of Pharmacology 9
4 Administration of Medications 24
5 Dosage Calculation 32
6 Autonomic Nervous System 42
7 Circulatory system (Cardiovascular ) 63
Hemostatic drugs: 68
1-Anti-coagulant
2- anti-platelet and Thrombolytic
3-Drugs used for Deficiency Anemia
8 Antihypertensive drugs 74
9 Drugs used in the treatment of 77
Dyslipidemia
10 Diuretics 80

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 Pharmacology
1- Pharmacology: concerns the study of drugs affect the function of host
tissues or combat infectious organisms.
2- Pharmacodynamic: study of the action of drugs on living tissues.
3- Pharmacokinetic: study of the processes of drug absorption, distribution,
metabolism and excretion.
4- Pharmacotherapeutics: Study of the use of drugs in treating disease.
5- Pharmacy: Science of preparing and dispensing medicines.
6- Posology: study of amount of drug that is required to produce therapeutic
effects.
7- Dose: Exact amount of a drug that is administered in order to produce a
specific effect.
8- Drug: Chemical substances that produces a change in body function.
9- Adverse effect: general term for undesirable and potentially harmful drug
effect,(aspirin caused erosion).
10- Side effect: drug effect other than the therapeutic effect that is usually
undesirable but not harmful.
11- Contraindications: situation or condition when a certain drug should not be
administered.
12- Agonist: drug that binds to its receptor and produces a drug action.
13- Antagonist: drug that binds to its receptor and prevents other drugs or
substances from producing an effect.
14- Chemical name: name that defines the chemical composition of a drug.
15- General name: nonproprietary, or common, name of a drug.
16- Brand or Trade name: patented proprietary name of drug sold by a specific
drug manufacturer.

Chemical Name Generic Name Brand or Trade Name

Acetylsalicylic acid Aspirin Aspin

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 71-Receptor: Receptor is a protein-molecule that recognizes and responds
to endogenous chemical signals, e.g. an acetylcholine receptor recognizes and
responds to its endogenous ligand, acetylcholine and drugs.
*specific location on the cell membrane or within the cell where a drug attaches
to produce its effect.
N Location of drug receptors Example
1 In the cell membrane Adrenergic receptor
2 In the cytoplasm Steroid receptor
3 In the nucleus Thyroid receptor

The binding of a drug to a receptor is determined by the following

forces:
1. Hydrogen bonds
2. Ionic bonds
3. Van der Waals forces
4. Covalent bonds
17- Therapeutic effect: desired drug effect to alleviate some condition or
symptom of disease.
18- Therapeutic index(TI) : ratio of the LD50 to the ED50.
19- LD50: lethal dose 50 , or dose that will kill 50 percent of the animals tested.
20- ED50:effective dose 50 , or dose that will produce an effect that is half of
the maximal response.

Drug sources: PHARMACOGNOSY

1) NATURAL
a) Plants: morphine, digitalis. Alkaloids are more common, including atropine
(belladonna plant), caffeine (coffee bean), and nicotine (tobacco leaf)
a) Animals: insulin, hormone(estrogens)
b) Microorganisms: penicillin, streptomycin, tetracycline, chloramphenicol
and erythromycin
c) Minerals: iron, calcium, magnesium.

2) SYNTHETIC: sulphonamides, antihistamines.

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 Application of pharmacology in Nursing practice
*Evaluation of nursing responsibility regarding drugs
Nurses' are responsibility regarding medication focused on the six rights:-

1- Drug administration.
2- Drug namely.
3- Gave the right drug to the right patient.
4- Gave the right dose by the right route.
5- Gave the right drug at the right time.
6- Right documentation was added.

Why the Nurses' are responsibility regarding medication focused on the six
rights?

The six rights guarantee only that a drug will be administered as prescribed.
Nurse, to gather with physicians and pharmacists, participate in system of checks
and balances designed to promote beneficial effects and minimize harm.
*Explain why the system of checks and balances, is important for nurse. to
detect mistakes made by pharmacists and prescribers - and mistakes will be
made, gave the example for this mistakes?
*Explain with an example mistakes made by pharmacists and prescribers?
When our system of checks and balances, the nurse has an important role as patient
advocate. It is your responsibility to detect mistakes made by pharmacists and
prescribers .
How mistakes will be made, with Example:
1- Prescribers may overlook potential drug interactions.
2- may be unaware of alterations in the patients status that would preclude use a
particular drug.
3-Select the correct drug but may order an inappropriate dosage or route of
administration.

The nurse it’s the last line of defense against medication errors, as the patient
advocate.

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 Application of pharmacology in patient care
In discussing the applications of pharmacology in patient care, we focus on seven
aspects of drug therapy:

1- Pre administration assessment

*Baseline data are needed to evaluate drug responses, both therapeutic and
adverse. (if we plan to give drug to lower blood pressure we must know the
patient's blood pressure prior to treatment).

2-Dosage and administration

(eg, some oral preparations must not be chewed or crushed, some should be
taken with fluids, some should be taken with meals, whereas others should
not)

3- Evaluated and promoting therapeutic effects.

Nifedipine, for example, is given for tow cardiovascular disorders:

hypertension and angina pectoris. When the drug is used for hypertension
you should monitor for a reduction in blood pressure. In contrast, when this
drug is for angina, you should monitor for a reduction in chest pain).

4- Minimizing adverse effects

Eg,(aspirin caused gastric erosion, hypoglycemia caused by insulin).

5- Minimizing adverse interactions

When a patient is taking two or more drugs, those drugs may interact with
one another to :

(eg, oral contraceptives to protect against pregnancy can be reduced by

carbamazepine(an antiseizure drug)

6- Making PRN(orders are common needed) decisions

How much drug to gave and when to gave

7- Managing toxicity

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 Mast to now the early signs of toxicity and the procedure for toxicity
management.

*Identifying height-risk patients.

Prevent an individual to adverse reaction(high-risk) from specific drug we

mast to understand the important predisposing factors:

*write the factors that Prevent an individual to an adverse reaction(high-risk)

from specific drug?

1- Pathphysiology (especially liver and kidney impairment).

2- Genetic factors.
3- Drug allergy.
4- Pregnancy.
5- Old age.
6- Extreme youth.
To identify such patients, we use three principal tools:
(Patient history, physical examination and laboratory data)

((Reduce the interaction and intensity of adverse interactions))

*Numerate the point that reduce the interaction and intensity of adverse
interaction?

Reduce the interaction and intensity of adverse interactions in several ways:

1- Take drug history.

2- Advising the patient to avoid over the counter that can interact with the
prescribed medication.

3- Monitoring for adverse interaction known to occur between the drugs the
patient is taking.

4- Being alert for as- yet unknown interaction.

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 Application of pharmacology in patient Education

Very often, the nurse is responsible patients about medications. In your role as
educator, you must give the patient the following information:

1- Drug name and therapeutic category (eg, penicillin: antibiotic).

2- Dosage size.(how much drug to take and when to take(eg. Insulin)).
3- Dosing schedule.(If one dose missed, the omitted dose should be taken
together with the next scheduled dose However, if three or more dose are
missed, a new cyclie of administration must be initiated).
4- Route and technique of administration. (e.g. some oral preparations must not
be chewed or crushed, some should be taken with fluids, some should be
taken with meals, whereas others should not).
5- Expected therapeutic response and when it should develop.
6- Nondrug measures to enhance therapeutic responses(eg. Enhancing drug
therapy of hypertension through weight reduction).
7- Duration of treatment.(patient must now when to taken their medicine, and
when must be stop.
8- Method of drug storage.
9- Symptoms of major adverse effects, and measures to minimize discomfort
and harm.(eg, Insulin over dose can cause decrease in blood glucose level
early signs of hypoglycemia include sweating and increased heart rate)
10- Major adverse drug- drug and drug food interactions(eg. Phenelzine an
antidepressant can cause dangerous elevations in blood pressure if taken
with amphetamines or with cretin food fig, avocados, most cheeses)
11-Whom to contact in the event of therapeutic failure, severe adverse
reactions, or severe adverse interaction.

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 Pharmacokinetics
Is the study of drug movement throughout the body also in cloud drug metabolism
and excretion.
There are four basic pharmacokinetic processes:
1- Absorption.
2- Distribution.
3- Metabolism.
4- Excretion.
1- Absorption: movement of a drug from its site of administration into the
body.
Factors affecting drug absorption:
1-Rate of dissolution.
Drugs in formulations that allow rapid dissolution have a faster onset than
drugs formulation for slow dissolution.
2- Surface area.
Orally administered drugs are usually absorption from the small intestine
rather than stomach, because of its lining of microvilli, has an extremely
large surface area, than stomach.
3- Blood flow.
The greater the concentration gradient, the more rapid absorption will be
4- Lipid solubility.
Lipid solubility drugs can readily cross the membranes that separate tham
the blood, whereas drugs of low lipid solubility.
5- PH partitioning.
Absorption of drugs will be enhanced when difference between the pH of
plasma and the pH at the site of administration (ion trapping of drugs
depending of tendency to ionized in the plasma and the site of
administration).

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 Absorption
Absorption is the movement of a drug from its site of administration into the
bloodstream for distribution to the tissues.
Bioavailability :A measure of the extent of drug absorption (from 0% to 100%) in
the systemic circulation.
For example, a drug that is absorbed from the intestine must first pass through
the liver before it reaches the systemic circulation.
First-pass effect the initial metabolism in the liver of a drug absorbed from the
gastrointestinal tract before the drug reaches systemic circulation through the
bloodstream.
Enterohepatic Recirculation:
It meaning a repeating cycle in which a drug moves from the liver into
duodenum (via the bile duct and then back to the liver (via the portal blood).

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 Distribution
Distribution refers to the transport of a drug by the bloodstream to its site of action.
1-Areas of rapid distribution include the heart, liver, kidneys, and brain.
2-Areas of slower distribution include muscle, skin, and fat.
*Only drug molecules that are not bound to plasma proteins can freely
distribute to extravascular tissue (outside the blood vessels) to reach their site
of action.
*If a drug is bound to plasma proteins( drug-protein complex) is generally too
large to pass through the walls of blood capillaries into tissues.
E.X: Albumin is the most common blood protein.
When an individual is taking two medications that are highly protein bound, the
medications may compete for binding sites on the albumin molecule. Because of
this competition, there is more free, unbound drug. This can lead to an
unpredictable drug response called a drug-drug interaction.
*Explant why when take two drugs on be more effect than anther?
drug-drug interaction: occurs when the presence of one drug decreases or
increases the actions of another drug that is administered concurrently (i.e., given
at the same time).

N.O:
1- highly water soluble (hydrophilic) will have a smaller volume of distribution
and high blood concentrations.
2-fat-soluble drugs (lipophilic) have a larger volume of distribution and low blood
concentrations.
There are some sites in the body into which it may be very difficult to distribute a
drug. These sites typically either have a poor blood supply (e.g., bone) or have
physiologic barriers that make it difficult for drugs to pass through (e.g., the
brain due to the blood-brain barrier).

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 Metabolism (biotransformation)
Metabolism is also referred to as biotransformation. It involves he biochemical
alteration of a drug into an inactive metabolite,a more soluble compound, a more
potent active metabolite (as in the conversion of an inactive prodrug to its active
form),or a less active metabolite. Metabolism is the next step after absorption and
distribution.
Hepatic metabolism involves the activity of a very large class of enzymes known
as cytochrome P-450 enzymes (or simply P-450 enzymes), also known as
microsomal enzymes.

N.O: water-soluble drugs (polar or hydrophilic [“water loving”]) molecules may be

more easily metabolized by simpler chemical reactions such as hydrolysis.
The biotransformation capabilities of the liver can vary considerably from patient
to patient. The various factors that can alter the biotransformation include genetics,
diseases, and the concurrent use of other medications

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 Patients who are slow acetylators have a physiologic makeup that causes certain
drugs to be metabolized more slowly than usual in a chemical step known as
acetylation.

Excretion
Excretion is the elimination of drugs from the body. Whether they are parent
compounds or active or inactive metabolites, all drugs must eventually be removed
from the body.
The primary organ responsible for this elimination is the kidney.
Two other organs that play an important role in the excretion of drugs are the
liver and the bowel.
Less common routes of elimination are the lungs and the sweat, salivary, and
mammary glands.
fat-soluble drugs, are in the bile, they may be reabsorbed into the
bloodstream, returned to the liver, and again secreted into the bile. This
process is called enterohepatic recirculation.
half-life :is the time required for one-half (50%) of a given drug to be removed
from the body.
It is a measure of the rate at which the drug is eliminated from the body
N.O: After about five half-lives, most drugs are considered to be effectively
removed from the body.

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 The kidneys themselves are also capable of metabolizing various drugs, although
usually to a lesser extent than the liver.
The actual act of renal excretion is accomplished through glomerular filtration,
active tubular reabsorption, and active tubular secretion. Free (unbound) water-
soluble drugs and metabolites go through passive glomerular filtration. Many
substances present in the nephrons go through active reabsorption and are taken
back up into the systemic circulation and transported away from the kidney. This
process is an attempt by the body to retain needed substances.

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 Steady state refers to the physiologic state in which the amount of drug removed
via elimination (e.g., renal clearance) is equal to the amount of drug absorbed with
each dose.

Onset, Peak, and Duration

The pharmacokinetic terms absorption, distribution, metabolism,and excretion are
all used to describe the movement of drugs through the body.
onset of action is the time required for the drug to elicit a therapeutic response.
peak effect is the time required for a drug to reach its maximum therapeutic
response.
duration of action of a drug is the length of time that the drug concentration is
sufficient (without more doses) to elicit a therapeutic response.

peak level (highest blood level) and trough level (lowest blood
level) of a drug. If the peak blood level is too high, then drug
toxicity may occur.( overdose of a drug with sedative properties).

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 PHARMACODYNAMICS
Pharmacodynamics is concerned with the mechanisms of drug action in living
tissues.
Mechanism of Action
Drugs can produce actions (therapeutic effects) in several ways.

Drugs can exert their actions in three basic ways: through receptors, enzymes, and
nonselective interactions.
1- Receptor Interactions: specific location on the cell membrane or within the
cell where a drug attaches to produce its effect.

Drug-receptor interaction is the joining of the drug molecule with a reactive site
on the surface of a cell or tissue.
The degree to which a drug attaches to and binds with a receptor is called its
affinity.

Efficacy is the relationship between receptor occupancy and the ability to initiate a
response at the molecular, cellular, tissue or system level.

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 2-Enzyme Interactions
Enzymes are the substances that catalyze nearly every biochemical reaction in a
cell.
Drug-enzyme interaction (selective interaction): occurs when the drug chemically
binds to an enzyme molecule in such a way that it alters (inhibits or enhances) the
enzyme’s interaction with its normal target molecules in the body.

3-Nonselective Interactions
Drugs with nonspecific mechanisms of action do not interact with receptors or
enzymes.
Some cancer drugs and antibiotics have this mechanism of action
This defect may be an improperly formed cell wall that results in cell death
through cell lysis, or it may be the lack of a necessary energy substrate, which
leads to cell starvation and death (normal metabolic process).

drug interaction:
alteration of the action of one drug by another is referred to as drug interaction.
A drug interaction can either increase or decrease the actions of one or both of
the involved drugs. Drug interactions can be either beneficial or harmful.
Many terms are used to categorize drug interactions.
1-additive effects: when two drugs with similar actions are given together (1 + 1 =
2) . antihistamine and opioid combinations (e.g., promethazine and codeine) for
treatment of cold symptoms, and acetaminophen and opioid combinations (e.g.,
acetaminophen and oxycodone) for treatment of pain.
2-Synergistic effects occur when two drugs administered together interact in such
a way that their combined effects are greater than the sum of the effects for each
drug given alone (1 + 1 = greater than 2). The combination of
hydrochlorothiazide with lisinopril for the treatment of hypertension is an
example.
3-Antagonistic effects are said to occur when the combination of two drugs results
in drug effects that are less than the sum of the effects for each drug given
separately (1 + 1 = less than 2). An example of this type of interaction occurs
when
the antibiotic ciprofloxacin is given simultaneously with antacids, vitamins, iron,
or dairy products. These drugs reduce the absorption of ciprofloxacin and lead
to decreased effectiveness of the antibiotic.
4-Incompatibility is a term most commonly used to describe parenteral drugs.
Drug incompatibility occurs when two parenteral drugs or solutions are mixed
together and the result is a chemical deterioration of one or both of the drugs or
the formation of a physical precipitate. The combination of two such drugs
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 usually produces a precipitate , haziness , or color change in the solution.
Before administering any intravenous medication, the nurse must always
inspect the bag for precipitate. If the solution appears cloudy or if visible flecks
are seen, the bag must be discarded and not given to the patient.

pharmacokinetics: absorption, distribution, metabolism and excretion.

when there is competition between two drugs for metabolizing enzymes, such as
the cytochrome P-450 enzymes. This change in metabolism of one or both drugs
can lead to subtherapeutic or toxic drug actions.
e.g:
Excretion :amoxicillin with probenecid Inhibits the secretion of amoxicillin into
the kidneys Elevation and prolongation of plasma levels of amoxicillin (can be
beneficial.
Absorption: Antacid with levofloxacin Antacids bind to the levofloxacin
preventing adequate absorption Decreased effectiveness of levofloxacin, resulting
from decreased blood levels (harmful).
An allergic reaction (also known as a hypersensitivity reaction)
involves the patient’s immune system. Immune system proteins known as
immunoglobulins (immune response) Various chemical mediators, such as
histamine,as well as cytokines and other inflammatory substances
(e.g., prostaglandins) usually are released during this process.
This response can result in reactions ranging from mild reactions such as skin
erythema or mild rash to severe, even life-threatening reactions such as
constriction of bronchial airways and tachycardia.

phosphate dehydrogenase (G6PD) deficiency. This disease affects

approximately 100 million people.
drug-induced hemolysis aspirin. Approximately 13% of African-American men
and 20% of African-American Women and sulfonamides, antimalarials, and
aspirin, patients with this deficiency may suffer life-threatening hemolysis of the
red blood cells.

DRUGS TO AVOID IN PATIENTS WITH GLUCOSE-6-PHOSPHATE

DEHYDROGENASE DEFICIENCY:
Aspirin, , Nitrofurantoin, Primaquine, Probenecid, Sulfonamides.

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 Sources of individual variation
– Each patient is unique in ability to respond and to how they each
respond, but formation of “IDEAL DRUG” will lessen this variation
 Age- very important factor
 Sex- due to hormonal differences
 Weight- less effective and longer lasting in obese individuals
(storage in fat)
 Kidney & liver functions - elimination of drug
 Genetic variables- tolerance, allergy (though not always
genetic)

DRUG THERAPY DURING PREGNANCY

Transfer of both drugs and nutrients to the fetus occurs primarily
1-diffusion across the placenta, although not all drugs cross the placenta.
2-Active transport requires the expenditure of energy and often involves some
sort of cell-surface protein pump.
factors that contribute to the safety or potential harm of drug:
therapy during pregnancy can be broadly broken down into three
areas: drug properties, fetal gestational age, and maternal factors.
1- Drug properties that impact drug transfer to the fetus include the drug’s
chemistry, dosage, and concurrently administered drugs.
Examples of relevant chemical properties include molecular weight, protein
binding, lipid solubility, and chemical structure. Important drug dosage
variables include dose and duration of therapy.
2- Fetal gestational age . Gestational age is also important in determining when a
drug can most easily cross the placenta to the fetus. The fetus is at greatest risk for
drug-induced developmental defects during the first trimester of pregnancy, and
during the last trimester, the greatest percentage of maternally absorbed drug gets
to the fetus, because of enhanced blood flow to the fetus, increased fetal surface
area, and increased amount of free drug in the mother’s circulation.
3- Any change in the mother’s physiology can affect the amount of drug to which
the fetus may be exposed, Maternal kidney and liver function affect drug
metabolism and excretion

N.O.certain situations that require their use. Without drug therapy, maternal
conditions such as hypertension,epilepsy, diabetes, and infection could seriously
endanger both the mother and the fetus, and the potential for harm far
outweighs the risks of appropriate drug therapy.
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 DRUG THERAPY DURING BREASTFEEDING
Breastfed infants are at risk for exposure to drugs consumed
by the mother.
The primary drug characteristics that increase the likelihood of drug transfer via
breastfeeding include fat solubility, low molecular weight, nonionization, and
high concentration.

CONSIDERATIONS FOR NEONATAL AND PEDIATRIC PATIENTS

Pediatric patients are defined based on age. A neonate is defined as between
birth and 1 month of age. An infant is between 1 and 12 months of age, and a
child is between 1 and 12 years of age.
Certain drugs may be more toxic, whereas others may be less toxic.
Physiology, Pharmacokinetics and Pharmacodynamics
Pediatric patients handle drugs much differently than adult patients, based
primarily on the immaturity of vital organs.
For instance, tetracycline may permanently discolor a young person’s teeth;
corticosteroids may suppress growth when given systemically (but not when
delivered via asthma inhalers, for example); and quinolone antibiotics
may damage cartilage.

Dosage Calculations for Pediatric Patients

Because pediatric patients (especially premature infants and neonates) have
small bodies and immature organs, they are very susceptible to drug
interactions, toxicity, and unusual drug responses. Pediatric patients require
different dosage calculations than do adults.
Many formulas for pediatric dosage calculation have been used throughout the
years. Formulas involving age, weight, and body surface area (BSA)

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 CONSIDERATIONS FOR ELDERLY PATIENTS
Drug therapy in the elderly is more likely to result in adverse effects and toxicity.
Elderly( geriatric):patient is defined as a person who is 65 years of age or older.
more people died of infections than of chronic illnesses such as heart disease,
cancer, and diabetes.

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 Pharmacokinetic Changes
Elderly patients are hospitalized frequently due to adverse drug reactions. Many
people, including the elderly, use complementary and alternative medicines such as
herbal remedies and dietary supplements, which can interact with prescription
drugs. The simultaneous use of multiple medications is called polypharmacy.
“Start low and go slow,” which means to start with the lowest possible dose
(often less than an average adult dose) and increase the dose slowly, based on
patient response.

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 Characteristics of commonly Used Routes of Administration
There are four major groups of routes administration:
1- Enteral (GI tract).
2- parenteral Parenteral (Injection Intravenous (IV), intramuscular (IM), and
subcutaneous (sub Q).
3- Topical, Transdermal (subtype of topical).
4- Inhalational
The distinguishing characteristics of the major routes are summarized in below :

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 27
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 The nurse’s responsibility when a client refuses to take a medication.
1- Determine the reason for the refusal.
2-Provide information regarding risk of refusal.
3- Notify the provider, and document the refusal and actions taken.
4-The nurse should check with the prescriber regarding the dose prescribed

How this medication error could have been prevented.

1. The nurse did not use two acceptable client identifiers.
2. The nurse relied on the client to respond to her name . Because the client had
been asleep, she may have simply responded to being awakened.
3. The nurse should have verified the client’s identification by checking the
identification band name, identification number, and/or photograph.
4. The nurse should also check for allergies by asking the client, looking for an
allergy bracelet, and reviewing the medical administration record.

5.Never give medications that you have not drawn up or prepared yourself.
6.Minimize the use of verbal and telephone orders. If used, be sure to repeat the
order to confirm with the prescriber. Speak slowly and clearly, and spell the
drug name aloud.
7. Avoid abbreviations, medical shorthand, and acronyms because they can lead
to confusion, miscommunication, and risk of error (see the Teamwork and
Collaboration: Legal and Ethical Principles box on p. 68.).
8.Never assume anything about any drug order or prescription, including route.
If a medication order is questioned for any reason (e.g., dose, drug, indication),
never assume that the prescriber is correct. Always be the patient’s
advocate and investigate the matter until all ambiguities are resolved.
9. Never use trailing zeros (e.g., 1.0 mg) in writing and/or transcribing medication
orders. Use of trailing zeros is associated with increased occurrence of
overdose. For example, “1.0 mg warfarin sodium” could be misread as “10 mg
warfarin,” a tenfold dose increase. Instead, use “1 mg” or even “one mg.”
10. Failure to use leading zeros can also lead to overdose. For example, .25 mg
digoxin could be misread as 25 mg digoxin, a dose that is 100 times the dose
ordered. Instead, write “0.25 mg.”
11.Make sure the weight of the patient is always recorded before carrying out a
medication order to help decrease dosage errors.
12.Always suspect an error whenever an adult dosage form is dispensed for a
pediatric patient.

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 Mechanism of action:
How the medication produces the desired therapeutic effect.
Toxicity:
A serious adverse effect usually caused by excessive dosing.

Comparing oral Administration with parenteral Administration :

1- Emergencies that rapid onset of drug action.
2- Situations in which plasma drug levels must be tightly controlled.(Because of
variable absorption, oral administration does not permit tight control of drug
levels).
3- Treatment with drugs that would be destroyed by gastric acidity, digestive
enzymes, or hepatic enzymes if given orally(eg, insulin, penicillin G,
nitroglycerin).
4- Treatment with drugs that would cause severe local injury if administered by
mouth(eg, certain anticancer agent ).
5- Treating a systemic disorder with drugs that cannot cross membranes( eg,
quaternary ammonium compounds).
6- Treating conditions for which the prolonged effects of a depot preparation
might be desirable.
7- Treating patients who cannot or will not take drugs orally.

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 PHARMACEUTICS
Pharmaceutics: is the science of dosage form design.

Classification of pharmaceutical dosage forms according to physical

properties:
1- Gaseous dosage forms Inhaled.
2- Liquid dosage forms Rectal.
3- Semisolid dosage forms Topical.
4- Solid dosage forms Oral.

Enteric-coated tablets, on the other hand, have a coating that prevents them from
being broken down in the acidic pH environment of the stomach and therefore are
not absorbed until they reach the higher (more alkaline) pH of the intestines and
protect the stomach lining from the local effects of the drug.
*This pharmaceutical property results in slower dissolution and therefore slower
absorption.
*Particle size within a tablet or capsule can make different dosage forms of
the same drug dissolve at different rates, become absorbed at different rates,
and thus have different times to onset of action.
*Combination dosage forms contain multiple drugs in one dose. Examples of
these combination forms include the cholesterol and antihypertensive
medications atorvastatin/amlodipine tablets called Caduet . There are large
numbers of such combination dosage forms.
The ability to crush a tablet or open a capsule can facilitate drug administration
when patients are unable or unwilling to swallow a tablet or capsule and also when
medications need to be given through an enteral feeding tube. Capsules, powder, or
liquid contents can often be added to soft foods such as applesauce or pudding, or
dissolved in a beverage.
*Granules contained in capsules are usually for extended drug release and
normally should not be crushed or chewed by the patient. However, they can often
be swallowed when sprinkled on one of the soft foods.

US ORAL PREPARATIONS

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 DRUG ABSORPTION OF VARIOUS ORAL PREPARATIONS
Oral disintegration, buccal tablets, and Fastest
oral
soluble wafers
Liquids, elixirs, and syrups
Suspension solutions
Powders
Capsules
Tablets
Coated tablets
Enteric-coated tablets Slowest

DOSAGE FORMS
Enteral Tablets, capsules, oral soluble wafers, pills, timed-release
capsules, timed-release tablets, elixirs, suspensions,
syrups, emulsions, solutions, lozenges or troches, rectal
suppositories, sublingual or buccal tablets
Parenteral Injectable forms, solutions, suspensions, emulsions,
powders for reconstitution
Topical Aerosols, ointments, creams, pastes, powders, solutions,
foams, gels, transdermal patches, inhalers, rectal and
vaginal suppositories

N.B:
1-Enteric-coated tablets should not be administered with antacids, milk, or other
alkaline substances because enteric-coated agents require the acid environment of
the stomach to be effective.
2- Enteric-coated tablets should not be crushed before administration because
crushing will
alter absorption.
3- Suspensions and emulsions must be shaken thoroughly immediately before use
because
the separation that occurs after standing for a short period will alter the dosage if
used in the
separated form
4- Suspensions are never administered intravenously.

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Assistant Professor: Ashraf Saddieak Alias
 Dosage Calculation
Metrology
Metrology : is the science of weight and measures .
Two distinct system of weight and measures are used at the time?
1- Apothecarie’s system
2- Metric system.
Apothecarie’s system (imperial system):
Apothecarie’s system units for weight:
Drachm (dr)= 60 grains (gr)
Ounce (oz or z)= 8 drachms
Pound (lb) =12 ounce

Apothecarie’s system units for liquids:

Fluid drachm (fl dr)= 60 minims (M)
Fluid ounce (fl oz or fz)= 8 Fluid drachms
Pint (o)=16 Fluid ounce

Metric system : introduce by French in 1791

Units of the metric system for weighing solids:-

Milligram (mg) = 1000 micrograms (ug)

Gram (g) = 1000 milligrams
Kilogram (kg) = 1000 grams

Units of the metric system for measuring liquids:-

Milliliter (ml) = 1000 microliters (ul)
Liter (L) = 1000 milliliters (ml)

Conversions from the apothecaries system to metric system

Grain = 0.06 grams Minim = 0.06 milliliter

Drachm = 4 grams Fluid Drachm = 4 milliliter
Ounce = 30 grams Fluid ounce = 30 milliliter
Pound 2.2 lb = 1 kg Pint = 500 milliliter
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Assistant Professor: Ashraf Saddieak Alias
 Household measures
Teaspoonful = 4 ml
Tablespoonful = 15 ml
Coffee cupful = 30 ml
Teacupful = 150 ml
Glassful = 250 ml

1)Calculate the total dose of tetracycline drug (2 mg / kg) given to patient weight
(150 kg)?

mg kg
2 1
X 150
2 x 150
X= = 300 mg/patient
1

2) Calculate the volume of injection of Sulfonamides (2mg/kg) given to patient

weight (70 kg)?

Concentration of drug (2%)

% = g/100 ml

2% = 2g/100 ml
g = 1000 mg

mg ml
2000 100
X 1
2000
X= = 20 mg/ml
100

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Assistant Professor: Ashraf Saddieak Alias
 mg kg
2 1
X 70

X = 140 mg/patient

mg ml
20 1
140 X

140
X= = 7 ml/patient
20

General Rounding Guidelines

If the number to the right is equal to or greater than 5, round up by adding 1 to the
number on the left.
If the number to the right is less than 5, round down by subtracting 1 from the
number on the left.
For dosages less than 1.0, round to the nearest hundredth.
For example: The calculated dose is 0.746 mL. Look at the number in the
thousandths place (6). Six is greater than 5. To round to hundredths, add 1 to 4
and drop the 6. The rounded dose is 0.75 mL.
For dosages greater than 1.0, round to the nearest tenth.
Dosage Calculations using Ratio and Proportion
Process for calculating solid, liquid and injectable dosage using ratio and
proportion
STEP 1: What is the dose needed? Dose needed = Desired
STEP 2: What is the dose available? Dose available = Have
STEP 3: Do the units of measurement need to be converted? Convert the unit of
measurement of what is desired to the unit of measurement of what is
available.
STEP 4: Determine the quantity of the dose available. This refers to how the
medication is provided, such as 2 mL or 3 tablets.

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Assistant Professor: Ashraf Saddieak Alias
 STEP 5: Set up an equation using knowledge about basic equivalents and solve for
X.

STEP 6: Reassess to determine if the amount to be given makes sense.

Solid dosage
Example: The provider prescribes phenytoin (Dilantin) 0.2 g PO, TID. The amount
available is 200mg/capsule. How many capsules should the nurse give?
Follow the steps:
STEP 1: Desired0.2 g
STEP 2: Have200 mg
STEP 3: converted (g ≠ mg)
Desire: g
Have: mg
0.2 g = X mg
Equivalents:
1 g = 1,000 mg (1 • 1,000)
Therefore:
0.2 g = 200 mg (0.2 • 1,000)
STEP 4: 1 capsule
STEP 5: Set up an equation and solve:

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Assistant Professor: Ashraf Saddieak Alias
 Liquid dosage
Example: The provider prescribes erythromycin oral suspension 0.25 g, PO,
The amount available is erythromycin oral suspension, 250 mg/mL. How many mL
should thenurse administer with each dose?
Follow the steps:
STEP 1: Desired0.25 g
STEP 2:Have250 mg
STEP 3: converted (g ≠ mg)
Convert the unit of measurement of what is desired to the unit of
measurement of what is available.
Desire: g
Have: mg
0.25 g = X mg
Equivalents
1 g = 1,000 mg (1 • 1,000)
Therefore:
0.25 g = 250 mg (0.25 • 1,000)
STEP 4: available1 mL
STEP 5: Set up an equation and solve:

STEP 6: Reassess to determine if the amount to be given makes sense. If there are
250mg/mL and the prescribed amount is 0.25 g, it makes sense to give 1 mL.
The nurse should administer erythromycin 1 mL PO 3 times a day.

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Assistant Professor: Ashraf Saddieak Alias
 Injectable Dosage
Example: The provider prescribes heparin 8,000 units subcutaneously, Q12 hr. The
amountavailable is 5,000 units/mL. How many mL should the nurse administer?
Follow the steps:
STEP 1: Desired8,000 units
STEP 2: Have5,000 units
STEP 3: Do the units of measurement need to be converted?
No (units = units)
STEP 4: dose available?1 mL
STEP 5: Set up an equation and solve:

STEP 6: Reassess to determine if the amount to be given makes sense. If there are
5,000 units/mL and the prescribed amount is 8,000 units, it makes sense to
give 1.6 mL.
The nurse should administer heparin 1.6 mL subcutaneously every 12 hr.

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Assistant Professor: Ashraf Saddieak Alias
 Dosages by Weight
Process for calculating dosage by weight using ratio and proportion
Medications may be prescribed in daily amounts per kg of body weight such as “5
mg/kg/day,” which is then divided into doses given throughout the day. The same
process as forcalculating oral dosages is used, but first the nurse must determine
the client’s weight in kg,the total daily dose, and the amount per dose.
Example: The provider prescribes cefixime (Suprax) 8 mg/kg/day PO to be given
in 2 divided doses. The client weighs 22 lb. The amount available is 100 mg/5 mL
suspension. How many mLshould the nurse administer per dose?
STEP 1: What is the client’s weight in kg?
2.2 lb = 1 kg
Client’s weight in lb = X kg
Set up an equation:

Cross multiply and solve for X:

2.2X = 22
X = 10 kg
STEP 2: What is the total daily dose?
Amount prescribed • kg weight (mg • kg) = total daily dose
8 mg/kg • 10 kg = 80 mg
STEP 3: What is the amount per dose?

STEP 4: What is the dose needed? Dose needed = Desired

Desired = 40 mg

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Assistant Professor: Ashraf Saddieak Alias
 STEP 5: What is the dose available? Dose available = Have
Have = 100 mg
STEP 6: Do the units of measurement need to be converted?
No (mg = mg)
STEP 7: What is the quantity of the dose available?
Quantity = 5 mL
STEP 8: Set up an equation using knowledge about basic equivalents.

STEP 9: Reassess to determine if the amount to be given makes sense. If there are
100mg/5 mL and the prescribed dose is 40 mg, it makes sense for the nurse to
give 2 mL.
The nurse should administer cefixime 2 mL PO with each dose.
IV flow rates

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Assistant Professor: Ashraf Saddieak Alias
 Q1)The nurse is administering a medication and the order reads: Give 250 mcg
PO now. The tablets in the medication dispensing cabinet are in milligram
strength. What is the right dose of the drug in milligrams?

0.25 mg

Q2)The nurse is administering a medication and the order reads: Give 0.125 mg
PO now. The tablets in the medication dispensing cabinet are in microgram
strength. What is the right dose of the drug in micrograms?
___________________________
125 mcg

Q3)child is to receive a medication that is dosed as 8 mg/kg. The child weighs 40

kg. What is the dose of medication that the nurse will administer to this child?
______

Q4)Dose ordered: magnesium sulfate 4 g On hand: magnesium sulfate 50%

vial

How much will you give? __8ML________

Q5)A toddler is to receive a daily dose of digoxin (Lanoxin) 2 mcg/kg/day IV.

The toddler weighs 88 pounds. Calculate the amount of medication in
milligrams that the toddler will receive.

Q6)

Grain 3 = grams Drachm 5 = grams

Fluid Drachm 8 = millilite
Pound 66 lb = kg Pint 7 = milliliter
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Assistant Professor: Ashraf Saddieak Alias
 Q7) The order reads: “Give levothyroxine (Synthroid) 50 mcg PO every morning.”
Which of these correctly depicts the dose in milligrams? ------ --------------
a. .05 mg
b. 0.05 mg
c. 0.050 mg
d. 50000 mg

Q8) The provider prescribes cefixime (Suprax) 8 mg/kg/day PO to be given in 2

divided doses. The client weighs 22 lb. The amount available is 100 mg/5 mL
suspension. How many mL should the nurse administer per dose?

*The nurse should administer cefixime 2 mL PO with each dose

Q9)Conversions from the apothecaries system to metric system

Minim 1 = milliliter
Drachm 2 = grams Fluid Drachm 4 = milliliter
Ounce 3 = grams Fluid ounce 2 = milliliter

Q10) The provider prescribes Ampicillin 1 g PO, TID. The amount available is
1000mg/capsule to patient weighs 90 kg . How many capsules should the nurse
give?

Q11) The provider prescribes Thiazides 8 mg/kg/day PO to be given in 4 divided

doses. The client weighs 44 lb. The amount available is 100 mg/5 mL suspension.
How many mL should the nurse administer per dose?

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Assistant Professor: Ashraf Saddieak Alias