General Pharmacology PDF

General Pharmacology  What is Pharmacology? Pharmacology: – Pharmacon (drugs) + Logos (studies) – The study of drugs 2  Drugs & Medicines Drug is called medicine when used in proper dosage form for safe administration All medicines are drugs but all drugs are not...

General Pharmacology  What is Pharmacology? Pharmacology: – Pharmacon (drugs) + Logos (studies) – The study of drugs 2  Drugs & Medicines Drug is called medicine when used in proper dosage form for safe administration All medicines are drugs but all drugs are not medicines 3  Definitions Clinical Pharmacology – Deals with the study of drug effects in humans beings, i.e. Healthy volunteers and patients Experimental Pharmacology – Deals with the study of drug effects in laboratory animals In vitro – isolated tissue In vivo – intact organism  Toxicology: – Deals with adverse (undesired) reactions of drugs & their treatment Pharmacogenetics: – How genetics influence the mode of drug actions (e.g. Metabolism) and biological variations of drug responses.  Pharmacokinetics: – How the body handles the drug – Includes absorption, distribution , biotransformation, and elimination Pharmacodynamics: – How drug handles the body – Deals with the biochemical and physiological effects of drugs on man  Drug Regulations Drugs are strictly regulated in all countries. In Saudi Arabia, Saudi Food and Drug Authority regulates the sale and use of drugs. Prescribing physician and dispensing pharmacists of scheduled drugs must be registered and prescribed forms must be filled 7 10/3/2024 Controlled Substances and their Schedules These are the drugs that are known to have abuse potential. They can cause psychological dependence or addiction Schedule I (C-I) Drugs High abuse potential and no accepted medical use (heroin) Schedule II (C -II) Drugs High abuse potential with severe dependence liability (morphine) 8 10/3/2024 Schedule III (C-III) drugs Less abuse potential than schedule II drugs and moderate dependence liability (Acetaminophen/Codeine) Schedule IV (C-IV) drugs Less abuse potential than schedule III drug and limited dependence liability (diazepam) Schedule V (C-V) drugs Limited abuse potential. Primarily small amounts of narcotics (codeine) use as antitussive or anti- diarrheals. 9 10/3/2024  Drug Development and Evaluation It takes intensive research and long time to identify a chemical that might have therapeutic value. It must undergo a series of scientific tests to evaluate its therapeutic and toxic effects. These tests are strictly regulated and are known as 1. Preclinical trials 2. Phase 1 studies 3. Phase 2 studies 4. Phase 3 studies 5. Post marketing surveillance For every 100,000 chemicals that are identified as 10 potential drugs, only 5 reach the market 10/3/2024 1. Preclinical Trials Drug are tested on laboratory animals for 1. To determine whether they have the presumed effects in living tissue 2. To evaluate adverse effects 2. Phase 1 studies If the drug passes preclinical trials, it is tested on humans because some drugs are therapeutic in animals but not in humans Healthy young male volunteers are selected for study. 11 10/3/2024 3. Phase 2 studies If the drug passes phase 1 trial, it is tested on patients that have the disease the drug was intended for. 4. Phase 3 studies If the drug passes phase 2 trial, it is tested on a large number of patient, a thousand or more. Patients are asked to keep record of effects they experience after use of drug. Unexpected effects can come to notice at any stage. 12 10/3/2024 5. Post marketing surveillance Drug are kept under surveillance even after approval and marketing. Many drugs have been found to produce unacceptable adverse effects after many years of use e.g. thalidomide 13  Criteria for drug classification Drugs can be classified in many ways based on 1. Chemical structure – Organophosphates 2. Location of action – Autonomic drugs 3. Purpose of medication – Antihypertensive 4. Name of plant – Opium alkaloids  Sources of drugs 1. Natural Sources: A. Plants B. Animals / Humans C. Micro-organisms D. Minerals 2. Semi-synthetic 3. Synthetic 4. Bio-synthetic  Sources of drugs 1. Natural forms: A. From Plants – Active principles are found in roots, leaves and seeds – E.g. Morphine (from Poppy capsules), B. From animals / humans – Hormones E.G. Insulin from Pig or Ox pancreas C. From micro-organism – Penicillin from Penicillium notatum D. Minerals – Calcium, Magnesium  Sources of drugs 3. Semi synthetic drugs Prepared by chemical modification of natural drugs in labs. E.g. Ampicillin from Penicillin-G The aim to make it better – more potent, more stable, less toxic. 4. Synthetic Drugs Prepared by chemical synthesis in pharmaceutical laboratories e.g. Sulphonamides  Sources of drugs 5. Bio-Synthetic Drugs Scientists use genetic engineering to alter bacteria to produce chemicals that are therapeutic and effective. Prepared by cloning of human DNA into bacteria such as E. Coli. E.g. human insulin  Drug Nomenclature Chemical name – Based on the chemical composition and structure e.g. acetyl salicylic acid Generic name (Official, Approved) – This name is used and chosen by official bodies e.g. Aspirin Proprietary name (Brand name, Company name) – The name given by the company which markets the drug – It is the commercial property of a pharmaceutical company good luck