Pharmacology A.
Passive absorption
Occurs mostly by diffusion
- The study or science of drugs
Higher to lower concentration movement
Drug – a chemical agent capable of producing biologic Drug does not require energy to move across
responses within our body the membrane
B. Active absorption
Medication – after a drug is administered Requires carrier such as enzyme or protein to
Drug names: move drug against a concentration gradient.
Requires energy
a. Chemical name – description of drug using the C. Pinocytosis
nomenclature of chemistry Cells carry a drug across their membrane by
b. Generic name – the nonproprietary name; engulfing the drug particles
much shorter and less complex than chemical
name NOTE!
c. Trade name – aka brand names; names under Since the GI tract is composed mostly of lipid
which a drug is marketed and protein, drugs that are fat-soluble passes
rapidly than water-soluble drugs.
BASIC AREAS OF PHARMACOLOGY
Bioavailability – term used to express the
extent of the drug absorption
DRUG ACTION - oral route drugs bioavailability = less than
Pharmaceutic phase 100%
- IV route drugs bioavailability = 100%
- 1st phase of drug action
- drug dosage forms First-pass effect – reduces the bioavailability of
- aka “dissolution” = a drug in a solid form must the drug; some drugs are metabolized in the
be disintegrated into small pieces to dissolve liver before proceeding to the desired site of
into a liquid administration
- how various dosage forms influence the way Factors influencing drug absorption:
the drug is absorbed and how the body
metabolizes the drug Drug administration (route)
- 80 % of drugs are taken by mouth Presence of food
Dosage formulation
Tablets = not 100% drug Stomach acidity
= excipients (fillers and inert substances) are
Rate of blood flow
added
GI motility
= enteric – coated tablet/capsules can remain in Status of absorptive
the stomach because disintegration cannot occur until
alkaline environment is reached
Route of Administration:
Pharmacokinetic phase
A. Enteral
- the study of drug movement throughout the
- Drug is absorbed into the systemic circulation
body
through the mucosa of the stomach and
- four basic pharmacokinetic processes:
small/large intestine
1. Absorption – movement of drug from its
- Sublingual route: drug is placed under the
site of administration into the bloodstream
tongue
- Buccal route: between cheek and gums
Half-life (t1/2)
B. Parenteral
- The time it takes for ½ of the drug
- A general term that means any route of
concentration to be eliminated
administration other than GI tract
4. Excretion – the elimination of drug from the
- Examples: Intravenous injection, intramuscular
body
injection, subcutaneous injections, etc
- Main route of drug elimination is through the
kidneys
C. Topical
- Delivers medication directly into the affected Biliary excretion: excretion of drugs by the intestine
area
- Examples: ointments, patches, eyedrops, Enterohepatic recirculation: when certain drugs are
sprays, inhaler in the bile, they may be reabsorbed int the
bloodstream, returned to the liver and secreted
D. Rectal again in the bile
- Administered through the anus
- Useful for local or systemic drug delivery
2. Distribution – the transport of drug by the
bloodstream to its site of administration
- Protein-binding effect: Some drug molecules
bound themselves to plasma proteins;
Albumin – the most common blood
protein and carries majority of inactive
drug molecules
Inactive drug – bounded drug
Active drug – not bounded drug; “free”;
causes pharmacologic response
A acid glycoprotein
Corticosteroid-binding globulin
Factors influencing distribution of drug:
Malnourishment (causes low serum
albumin level)
Abscesses
Exudates
Body glands
Tumor
Liver disease
Kidney disease
3. Metabolism – the biotransformation
- the biochemical alteration of a drug
- Liver: main organ for drug metabolism
- Influenced by:
Patient’s genetic formation
Diseases
Concurrent use of other
