JNTU B.Pharmacy III PHARMACOLOGY-I Previous Question Paper (January/February - 2023 - R17)

Drugs are derived from various natural and synthetic sources, which can be broadly classified as follows:

• Natural sources: These include plants (e.g., morphine from opium poppy, atropine from belladonna), animals (e.g., insulin from pancreas, heparin from liver), minerals (e.g., ferrous sulfate, liquid paraffin), and microorganisms (e.g., penicillin from Penicillium species).
• Synthetic sources: These are drugs synthesized in the laboratory through chemical processes, such as aspirin, sulfonamides, and many modern therapeutic agents.
• Semi-synthetic sources: These involve chemical modification of natural substances to improve efficacy or reduce toxicity, such as amoxicillin derived from 6-aminopenicillanic acid.
• Recombinant DNA technology: Modern biotechnology allows for the production of drugs like human insulin and growth hormone using genetically modified organisms.

Enzyme induction is the process by which a drug or chemical substance increases the rate of synthesis or decreases the rate of degradation of hepatic microsomal enzymes (specifically the cytochrome P450 system). This acceleration in enzyme activity leads to an increase in the rate of metabolism of the inducing drug itself or other co-administered drugs, often resulting in a decrease in their pharmacological effects and therapeutic efficacy.

Common examples of enzyme inducers include:

• Phenobarbitone: A classic barbiturate that induces various CYP450 isoenzymes.
• Rifampicin: A potent inducer used in tuberculosis treatment that significantly affects the metabolism of oral contraceptives and warfarin.
• Phenytoin: An anticonvulsant known to induce hepatic enzymes.
• Carbamazepine: An antiepileptic drug that acts as an auto-inducer, increasing its own metabolism over time.