PHARMACOLOGY
Introduction to Pharmacology:
● Pharmacology — study of biological effects of chemicals
○ Pharmakon means “drug”
○ Logia means “study of” or “knowledge of”
● Drugs — are chemicals that are introduced into the body to cause some sort of
change.
● Pharmacotherapeutics — or clinical pharmacology, is the branch of pharmacology
that uses drugs to treat, prevent, and diagnose disease.
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Addresses Two Concerns:
1. PharmacoDynamics — drugs effect on the body.
2. PharmacoKinetics — body’s response to the drug
a. Absorption — pagpasok ng droga sa fluid ng katawan or tissues.
O b. Distribution — pagalaw ng gamot sa ibang body fluids sa katawan.
c. Metabolism (Biotransportation) — mostly liver; liver acts as sewage system
treatment plan; it makes sure less active and remains those enzymes and
substances that can be used.
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d. Excretion — paglabas ng gamot sa katawan.
● Side Effects — most common
● Adverse Effects — hindi ganon inaasahan; commonly worse than side effects
Sources of Drugs:
1. Natural
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a. Plants
b. Animals
c. Minerals/Inorganic compounds
2. Synthetics — human made; made in laboratory
Drug Evaluation:
Food and Drug Administration
● An agency that regulates the development and sale of drugs.
● For every 100,000 chemicals that are identified as being potential drugs, only about 5
end up being marketed.
● Before receiving the final FDA approval, drugs must undergo a stage of development.
Stage of Development:
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1. Pre-clinical Trials
● Refers to the testing of chemicals with therapeutic value on laboratory animals.
● Purpose:
1. To determine whether they have the presumed effects in living tissues.
2. To evaluate any adverse effects.
● Reason for discarding some chemicals:
○ It lacks therapeutic activity
○ Too toxic
○ Is highly teratogenic (affect the fetus)
○ Safety margins are so small
2. Phase I (Checking SAFETY of medication)
● Uses human volunteers to test the drugs
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● Are performed by the clinical investigators
● Volunteers are fully informed of the risks and may be paid
● Volunteers are healthy, young men (because the drug can affect the ova of the
females and if the female affects the ova it cannot be replaced after birth but in
O males they can produce sperm every day, so less potential of complete
destruction/alteration of sperm unlike females. It should not be pediatrics or
elderly since pediatricians have a small body size and the distribution of drugs is
small and it can overdose and it will result in alteration/destruction in organ
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function and the organ is not fully developed. In elderly, it is not allowed to be in
clinical trials because degeneration means there is malfunction of organs.)
● Reasons for dropping the chemical include:
○ Lack of therapeutics effect in humans
○ Cause unacceptable adverse effects
○ Are highly teratogenic
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3. Phase II (Checking EFFICACY of medication)
● Allows clinical investigators to try out the drug in patients who have disease
that the drug is designed to treat.
● Patients are told about the possible effects of the drug and are informed about
the risk if consent to participate is given.
● Can be performed in hospitals, clinics, and doctor’s offices.
● Reasons for removal of chemical from further investigations include:
○ Is less effective than anticipated (cannot be treated the disease by the
drugs)
○ Is too toxic
○ Produce unacceptable adverse effects
○ Has low benefits-to-risk ratio (riskier)
○ Is no more effective than other drugs already in market
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4. Phase III
● Involves the use of drugs in a vast (maramihan) clinical market.=0=
● Prescribers are well informed about the known reactions to the drug and
precautions required; observe the patient closely.
● Reason for dropping the drug include:
○ Produces unacceptable adverse effects
○ Produce unexpected responses especially when used widely (more than
100 peoples)
5. FDA Approval
● NOTE! Only those drugs that receive FDA approval may be marketed
● NOTE! Entire drug development and approval process may take 5 to 6 years.
Some may be accelerated
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○ Ex. Delavirdine (Rescriptor) – for aids
● Brand Name/Trade Name – refers to an approved drug developed by the
pharmaceutical company; Straight printed
○ Ex. Levothroid, Synthroid
O ● Generic Name – is the original designation that a drug is given when the drug
company that developed it applies for the approval access; Always Italicized
○ Ex. Levothyroxine sodium
● Chemical Name – reflects the chemical structure of the drug .
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6. Phase IV
● Refers to continual evaluation after a drug was approved for marketing.
○ Ex. Dexfenfefluramine (Redux) – a diet drug
○ Rofecoxib (Vioxx)
Legal Regulation of Drugs:
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● Safety during the pregnancy: Category A-D and X
○ Category A – no risk to fetus
○ Category B – animal studies, shown adverse effects but there is adverse effects
in fetus; in pregnant women there is no risk
○ Category C – animal studies, shown adverse effects in fetus; in pregnant
women no adequate studies, so there is a chance that the medication is given by
the physician (It depends on the call of the doctor).
○ Category D – evidence in human fetal risk; maybe risk for the mother and not
for the fetus; It depends on the call of the doctor.
○ Category X – demonstrates fetal abnormalities on adverse effects.
● Controlled Drugs – are drugs with abuse potential
○ Ex. Morphine – for pain; lead to addiction
● Generic Drugs – drugs sold by their generic names
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● Orphan Drugs – are drugs that have been discovered but that are not financially
viable (masyadong mahal).
○ Orphan Drug Act of 1983 – develop the drugs
● Over-the-counter Drugs – are available without prescription for self-treatment (not
allowed frequently used) .
○ Ex. Advil (Ibuprofen), Biogesic (Paracetamol), or Cetirizine
Principles of Drug Administration:
To provide safe drug administration, the nurse should practice the “right” of drug
administration. They are:
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1. The right client – needs to be ensured by checking a second piece of identification.
This could be a picture on the chart, or a case number that is both on his chart and
wristband. This must be done before any medication is administered.
a. Ask the patient’s name
O b. Verification wrist band
2. The right drug – means that the client receives the drug that was prescribed by a
physician (MD), dentist (DDS), podiatrist (DPM), or an advanced practice nurse with the
license to write prescriptions (APRN).
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a. Before get in the cabinet
b. After pouring in a container
c. After returning to the cabinet
The components of a drug order as follows:
● Date and time the order is written
● Drug name (generic is preferred)
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● Drug dosage
● Route of administration
● Frequency and duration of administration (e.g. × 7 days, × 3 doses)
● Any special instructions for withholding or adjusting dosage based on nursing
assessment, drug effectiveness, or laboratory results.
● Physician or other health care provider’s signature or name if TO or VO
● Signature of licensed practitioners taking TO or VO.
*If any of these components are missing, the entire order is incomplete and the medication
should not be given.
3. The right dose – is the dose prescribed for a particular client. The nurse is responsible
for questioning any dose that looks too high or too low. Always consult a peer or
pharmacist if the dosage appears incorrect. Beware of pediatric doses that are based
on body weight. Weight can change daily so regular assessment of dosages is crucial.
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a. Checking physician order
The nurse implications include the following:
● Calculate the drug dose correctly
● Check the PDR, American hospital formulary, drug package inserts, or other drug
references for recommended range of specific drug doses.
4. The right time – is the time at which the prescribed dose should be administered.
a. OD (once a day)
b. BID (twice a day)
c. TID (thrice a day)
d. QID (four times a day)
e. PRN (as needed)
f. Standing order
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g. STAT (DURING EMERGENCY! only once)
5. The right route – is necessary for adequate or appropriate absorption.
a. Oral (sublingual, buccal)
b. Parenteral (IV, IM, ID, SC)
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Experience indicates that five additional rights are essential to professional nursing practice:
1. The right assessment
2. The right documentation
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3. The client’s right to education
4. The right evaluation
5. The client’s right to refuse
Measuring Systems:
1. Metric system – is a decimal system based on the power of ten.
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The basic unit of measurement are:
a. Gram for weight
b. Liter for volume
c. Meter for linear measurements or length
2. Apothecary system
a. Solids: grain (gr)
60 = 1 dram (dr)
8 dr = 1 ounce (oz)
b. Liquids: minim (min)
60 minim = 1 fluid dram (f dr)
8 f dr = 1 fluid ounce
3. Household system
a. Solids: pound (lb)
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1 lb = 16 ounces (oz)
b. Liquids: pint (pt)
2 pt = 1 quart (qt)
4 qt = 1 gallon (gal)
16 oz = 1 pt = 2 cups (c)
32 tablespoon (tbsp) = 1 pt
3 teaspoon (tsp) = 1 tbsp
60 drops (gtt) = 1 tsp
Methods for Calculation/Drug Calculations
Tablet Dosage Calculation:
● This formula is used to calculate the number of tables to be administered when given
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the required dose.
𝑅𝑒𝑞𝑢𝑖𝑟𝑒𝑑 𝐷𝑜𝑠𝑒 (𝑚𝑔)
𝑆𝑡𝑜𝑐𝑘 𝐷𝑜𝑠𝑒 (𝑚𝑔)
= 𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑡𝑎𝑏𝑙𝑒𝑠 𝑡𝑜 𝑏𝑒 𝑔𝑖𝑣𝑒𝑛
O 𝑅𝑒𝑞𝑢𝑖𝑟𝑒𝑑 𝐷𝑜𝑠𝑒 (𝑚𝑔)
Examples:
𝑆𝑡𝑜𝑐𝑘 𝐷𝑜𝑠𝑒 (𝑚𝑔)
𝑜𝑟
× 𝑣𝑜𝑙𝑢𝑚𝑒(𝑡𝑎𝑏) = 𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑡𝑎𝑏𝑙𝑒𝑠 𝑡𝑜 𝑏𝑒 𝑔𝑖𝑣𝑒𝑛
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1. A client is ordered 150 mg of aspirin. 300 mg aspirin tablets are available. How many
tablets would you give?
Given:
150 mg aspirin (ordered)
300 mg aspirin (available)
Solution:
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150 𝑚𝑔 1
= 300 𝑚𝑔
= 0. 5/ 2
𝑡𝑎𝑏𝑙𝑒𝑡𝑠
2. How many tablets containing 62.5 mcg will be required to give a dose of 0.125 mg?
Given:
0.125 mg (required)
62.5 mcg = 0.0625 mg (stock)
Solution:
0.125 𝑚𝑔
= 0.0625 𝑚𝑔
= 2 𝑡𝑎𝑏𝑙𝑒𝑡𝑠
Fluid Dosage Calculations:
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● This formula is used to calculate the amount of medication in solution for oral, IM, IV,
or SC injection to be administered when given a dosage, stock dose, and volume.
Method 1: Stock dose, required dose, volume
𝑅𝑒𝑞𝑢𝑖𝑟𝑒𝑑 𝐷𝑜𝑠𝑒 (𝑚𝑔) 𝑆𝑡𝑜𝑐𝑘 𝑉𝑜𝑙𝑢𝑚𝑒 (𝑚𝑙)
𝑆𝑡𝑜𝑐𝑘 𝐷𝑜𝑠𝑒 (𝑚𝑔)
× 1
= 𝑉𝑜𝑙𝑢𝑚𝑒 𝑡𝑜 𝑏𝑒 𝑔𝑖𝑣𝑒𝑛
Method 2: Ratio and frequency
𝑆𝑡𝑜𝑐𝑘 𝑑𝑜𝑠𝑒 × 𝑉𝑜𝑙𝑢𝑚𝑒 = 𝑅𝑒𝑞𝑢𝑖𝑟𝑒𝑑 𝑑𝑜𝑠𝑒 × 𝑋
Transpose
𝑆𝑡𝑜𝑐𝑘 𝑑𝑜𝑠𝑒 × 𝑋 = 𝑉𝑜𝑙𝑢𝑚𝑒 × 𝑅𝑒𝑞𝑢𝑖𝑟𝑒𝑑 𝑑𝑜𝑠𝑒
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62. 5 × 𝑋 = 5𝑚𝑙 × 100 𝑚𝑔
62. 5𝑋 = 500𝑚𝑙
500𝑚𝑙
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Method 3: Fractional equation
𝑋 =
𝑋 =8
62.5
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𝑆𝑡𝑜𝑐𝑘 𝑑𝑜𝑠𝑒 𝑅𝑒𝑞𝑢𝑖𝑟𝑒𝑑 𝑑𝑜𝑠𝑒
𝑉𝑜𝑙𝑢𝑚𝑒
× 𝑋
Examples:
1. A client is ordered 15 mg of Stemetil. You have 2 ml of solution on hand which contains
25 mg Stemetil. What volume of solution would you give?
Given:
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15 mg (ordered)
2 ml (stock volume)
25 mg (stock dose)
Solution:
15 𝑚𝑔 2 𝑚𝑙 30
25 𝑚𝑔
× 1
= 25
= 1. 2 𝑚𝑙
2. A dose of 75 mg of pethidine has been ordered. It is available in ampules containing
100 mg in 2 ml. How much are you going to administer?
Given:
75 mg (ordered)
100 mg (stock dose)
2 ml (stock volume)
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Solution:
75 𝑚𝑔 2 𝑚𝑙 150
100 𝑚𝑔
× 1
= 100
= 1. 5 𝑚𝑙
Intravenous Fluid Computation:
● Intravenous fluid must be given at a specific rate, neither too fast nor too slow. The
specific rate may be measured as ml/hour, L/hr, or drops/min. To control or adjust the
flow rate only drops per minute are used. The burette contains a needle or plastic
dropper which gives the number of drops per ml (the drop factor). A number of
different drop factors are available (determined by the length and diameter of the
needle).
Common drop factors are:
● 10 drops/ml (blood set)
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● 15 drops/ml (regular set; for adult)
● 60 drops/ml (microdrop; for pediatrics)
To measure the rate we must know:
O a. The number of drops
b. Time in minutes.
𝑣𝑜𝑙𝑢𝑚𝑒 (𝑚𝑙) × 𝑑𝑟𝑜𝑝 𝑓𝑎𝑐𝑡𝑜𝑟 (𝑑𝑟𝑜𝑝𝑠/𝑚𝑙)
𝑡𝑖𝑚𝑒 (𝑚𝑖𝑛)
= 𝑑𝑟𝑜𝑝𝑠/𝑚𝑖𝑛
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Examples:
1. 1500 ml IV Saline is ordered over 12 hours. Using a drop factor of 15 drops/ml. How
many drops per minute needs to be delivered?
Given:
1500 ml IV (ordered)
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12 hrs = 720 mins (time)
15 drops/ml (drop factor)
Solution:
1500 𝑚𝑙 × 15 𝑑𝑟𝑜𝑝𝑠/𝑚𝑙 22,500 𝑑𝑟𝑜𝑝𝑠
720 𝑚𝑖𝑛𝑠
= 720 𝑚𝑖𝑛𝑠
= 31. 25/31 𝑑𝑟𝑜𝑝𝑠/𝑚𝑖𝑛
Fried’s Rule:
𝐼𝑛𝑓𝑎𝑛𝑡𝑠 𝑎𝑔𝑒 𝑖𝑛 𝑀𝑂𝑁𝑇𝐻𝑆 × 𝐴𝑣𝑒𝑟𝑎𝑔𝑒 𝑎𝑑𝑢𝑙𝑡 𝑑𝑜𝑠𝑒
𝐶ℎ𝑖𝑙𝑑 𝑑𝑜𝑠𝑒 (𝑎𝑔𝑒 < 1 𝑦𝑒𝑎𝑟) = 150 𝑚𝑜𝑛𝑡ℎ𝑠
Young’s Rule:
𝐶ℎ𝑖𝑙𝑑 𝑎𝑔𝑒 𝑖𝑛 𝑌𝐸𝐴𝑅𝑆 × 𝐴𝑣𝑒𝑟𝑎𝑔𝑒 𝑎𝑑𝑢𝑙𝑡 𝑑𝑜𝑠𝑒
𝐶ℎ𝑖𝑙𝑑 𝑑𝑜𝑠𝑒 (1 − 2 𝑦𝑒𝑎𝑟) = 𝐶ℎ𝑖𝑙𝑑 𝑎𝑔𝑒 𝑖𝑛 𝑌𝐸𝐴𝑅𝑆 + 12
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Clark’s Rule:
87 × 15
𝐶ℎ𝑖𝑙𝑑 𝑑𝑜𝑠𝑒 = 150 𝑝𝑜𝑢𝑛𝑑𝑠
Mnemonics: A child whose name is FAM will be happy and say YAY if he will use his CP.
Anti-Infective Agents:
Development of Anti-infective Therapy
● 1920s Paul Ehrlich worked on developing a synthetic chemical effective against
infection-causing cells only (meaning, invading microorganism that causes infection).
○ Scientists discovered penicillin in a mold sample.
● 1935 The sulfonamides were introduced (sulfonamides prevent cells from having
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essential substances).
Mechanism of Action
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1. Interfere with biosynthesis of the bacterial cell wall (hindi agad mapapasukan ng
infection. Example, anti mycobacterial)
2. Prevent the cells of the invading organism from using substances essential to their
growth and development.
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3. Interfere with steps involved in protein synthesis
4. Interfere with DNA synthesis
5. Alter with permeability of the cell membrane to allow essential components to leak
out.
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