Pharmacology 1 Lecture Notes PDF

PHARMACOLOGY 1 FACULTY OF DENTISTRY 1 Enzyme-linked Receptors For example, receptors for insulin (receptor tyrosine kinase) 2  Nuclear Receptors Examples are receptors for sex steroids and glucoc...

PHARMACOLOGY 1 FACULTY OF DENTISTRY 1 Enzyme-linked Receptors For example, receptors for insulin (receptor tyrosine kinase) 2  Nuclear Receptors Examples are receptors for sex steroids and glucocorticoids. 3 4  Regulation of Receptors Receptors can be regulated by various mechanisms resulting in either their ✓Up-regulation or ✓Downregulation. 5 Regulation of Receptors 6 Dose-Response Relationship  Dose-Response Relationship The pharmacological effect of a drug depends on its concentration at the site of action, which, in turn, is determined by the dose of the drug administered. Such a relationship is called a ‘Dose-response Relationship’.  Graded Dose-response This curve, when plotted on a graph, takes the form of a rectangular hyperbola; if the dose is plotted on a logarithmic scale, a sigmoid- shaped log dose-response curve is obtained. (a) Dose-response curve; (b) Log dose-response curve. Therapeutic Index  Therapeutic Index It is the ratio of the median lethal dose to the median effective dose A. LD50: It is the dose of a drug that is lethal for 50% of the population. B. ED50: It is the dose of the drug that produces the desired effect in 50% of the population. The wider the value of the therapeutic index, the safer is the drug.  Dose–response curves of therapeutic effect (A) and adverse effect (B). Distance between ED50 and LD50 indicates safety margin. Therapeutic index For example, penicillin has a high therapeutic Index; Digitalis, has a narrow therapeutic index  Therapeutic Window It is the range of concentration of the drug produces the desired response with minimal toxicity. Drug Potency  Drug Potency The amount of a drug required to produce a desired response is called the potency of the drug. The lower the dose required for a given response, the more potent is the drug. For example, the analgesic dose of morphine is 10 mg and that of pethidine is 100 mg. Therefore, morphine is 10 times more potent than pethidine as an analgesic.  Increasing potency Dose-response curve (DRC) of two drugs—drug A (morphine) and drug B (pethidine) as analgesic— are compared.  Drug Efficacy Increasing Efficacy It is the maximum effect of a drug. For example, morphine is more efficacious than aspirin as an Analgesic Drug Efficacy VS Drug potency Increasing Efficacy Increasing potency