Introduction to Pharmacology

By Jim Clarke

Drug Naming

Chemical Name - describe chemical structure (rarely seen in medical literature)

Code Name - short letter-number combination used for experimental drugs

Generic Name - a name assigned to drug that can be used by anyone (not proprietary)

Trade Name - Proprietary name given to the drug by the manufacturer

Sources of Drug Information BNF- “official” drug bible - not used in clinical

practice except by pharmacists PDR - prepared by drug manufacturers. Is widely

available but not always thorough Facts & Comparisons Merck Manual - does not contain all drugs but is

very clinically oriented Various Drug “Handbooks”

Steps in Drug Approval Process

Isolation or development of new chemical Animal studies Investigational New Drug approval process

• Phase 1 - small numbers; healthy individuals• Phase 2 - small numbers; subjects with disease• Phase 3 - large multicenter clinical trials

New Drug Application

Abbreviations Used in Prescriptions b.i.d.; cc; c ; gtt; h.s.; p; p.o.; p.r.n.; q; qh;

q1h; q2h; q3h; q4h; q.i.d.; Px; Rx; s; ss; t.i.d.; Tx

Drug dosage forms

Oral Injectable (parenteral)

• Subcutaneous

• Intramuscular

• Intravenous

• Spinal

Topical Inhalational

Examples of Drugs Forms

Oral• Tablet; Capsule; Pill; Liquid

Injection• liquid

Topical• Paste; Suppositories; Ointment; Powder

Inhalational• Gas; liquid aerosol; dry powder aerosol

Metabolism of Drugs

Processes by which are transformed and deactivated• Site of drug biotransformation

• Liver - First- Pass effect in the liver

• Genetic differences exist in rates of metabolism

Example of First Pass Effect

Elimination of Drug Metabolites

By the Kidney- in the urine

Concept of “Half-Life”

Time required to metobolize 1/2 of the original dose of the drug

Use of this terms helps in determining how long a drug will remain in the body

Concept of Critical Threshold

Defined as the minimum level of drug concentration needed for the desired therapeutic effect to be present.

Other Dose-related Terms

Maximal Effect: greatest response that can be produced by a drug, above which no further response can be created (sometimes called “peak effect”

Onset: how long before a drug is able to exert a therapeutic effect

Duration: how long a drug effect lasts

Agonists and Antagonists An agonist causes a particular effect by

binding to the correct “receptor”

What is an “antagonist”?

An agent that blocks are reverses the actions of another medication

Activity Pick a commonly used drug Find out the following: How it is classified What it is used for How it is made Route of administration Side effects availability