Introduction to Pharmacology PDF

NCM 106: PHARMACOLOGY INTRODUCTION TO PHARMACOLOGY DEFINITION: PHARMACODYNAMICS: o Pharmacodynamics is the study of the effect of drugs on the body and their mechanism of action, i.e. what the drug does to the body. THERAPEUTICS:...

NCM 106: PHARMACOLOGY INTRODUCTION TO PHARMACOLOGY DEFINITION: PHARMACODYNAMICS: o Pharmacodynamics is the study of the effect of drugs on the body and their mechanism of action, i.e. what the drug does to the body. THERAPEUTICS: o Therapeutics deals with the use of drugs in the prevention and treatment of disease. TOXICOLOGY: o Toxicology deals with the adverse effect of the drug and also the study of poisons, i.e. detection, prevention and treatment of poisoning. (Toxicon =poison in Greek) CHEMOTHERAPY: o Chemotherapy is the use of chemicals for the treatment of infections. The term now also includes the use of chemicals to treat malignancies. PHARMACY: o Pharmacy is the science of identification, compounding and dispensing of drugs. It also includes collection, isolation, purification, synthesis and Standardization of medical substances. DRUG o Any chemical that affects the processes of a living organism HISTORICAL DEVELOPMENTS IN PHARMACOLOGY PEN PSAO (2700 BC) o It was the great herbal materia medica written in china. Kahun Papyrus (2000 BC) o Is an oldest Egyptian document containing information about veterinary medicines and uterine diseases of women. Ebers papyrus (1550 BC) o Also an Egyptian document containing information about the number of diseases and 829 prescriptions where castor oil, opium like drugs are being used. Hippocrates (460-375 BC) o A Greek physician is considered the “father of Medicine”. He was the first person who recognized disease as an abnormal reaction of the body. He introduces the use of metallic salts for the treatment of disease. Theophrastus (380-287 BC) o A great philosopher called the father of Pharmacognosy. He classified medicinal plants on the basis of medicinal characteristics. Dioscorides (AD 57)  NCM 106: PHARMACOLOGY o a Greek, produced one of the first materia medica of approximately 500 plants and remedies. Claudius Galen (AD 129–200) o He first attempted to consider the theoretical background of pharmacology. Paracelsus (1493–1541) o A Swiss scholar and alchemist, often considered the “grandfather of pharmacology”. He introduces the use of chemicals for treatment of disease. Valerius Cordus (1514-1544) o He compiled the first pharmacopeia where he described techniques for the preparation of drugs. MODERN PHARMACOLOGY Conversion of old medicines into modern pharmacology started taking shape following the introduction of animal experimentation and isolation of active ingredients from plants. Francois Megendie (1783-1855) o The first pharmacologist established the foundation of modern pharmacology. He developed experiments to elucidate the physiological processes and action of drugs on the body. Rudolph Buchheim (1820–1879) o German pharmacologist, a key figure in the development of pharmacology, who at the University of Dorpat, created the first pharmacological institute. Frederich Sertürner o German pharmacist’s assistant, isolated morphine—the first pure drug—in 1805 Claude Bernard (1813-1878) o considered the Father of experimental Medicine. He identifies the site of action of curare (arrow Poisoning). Oswald Schmiedeberg (1838–1921) o “Father of Pharmacology” established pharmacology as an independent discipline. He started teaching Pharmacology at the University of Strasbourg (France). John Jacob Abel (1857-1938) o founded first department of pharmacology in USA in the University of Michigan in 1893. In 1897 he established pharmacology department at Johns Hopkins University. Abel also co-founded the Journal of Pharmacology and Experimental Therapeutics in 1909. L. mayer Jones (1912-2002) o regarded as the father of modern veterinary pharmacology. He authored the first book of veterinary pharmacology therapeutics in 1954. BRANCHES OF PHARMACOLOGY: Following are the important branches or subdivision of Pharmacology: 1. Pharmacokinetics 2. Pharmacodynamics 3. Therapeutics  NCM 106: PHARMACOLOGY 4. Chemotherapy 5. Toxicology 6. Clinical Pharmacology 7. Pharmacy 8. Pharmacognosy 9. Pharmacogenetics 10. Pharmacoeconomics 11. Pharmacoepidemiology 12. Comparative Pharmacology 13. Animal Pharmacology 14. Pharmacoeconomics 15. Posology 1. Pharmacokinetics: o The word Pharmacokinetics is derived from two words, Pharmacon meaning drug and kinetics meaning putting in motion. It can be defined as: o “The branch of pharmacology that deals with the absorption, distribution, metabolism and excretion of drugs and their relationship with the onset, duration and intensity of the drug effect.” o What the body does to the drug is pharmacokinetics. For example, the absorption, distribution, metabolism and excretion of Paracetamol is included in Pharmacokinetics. 2. Pharmacodynamics: o Pharmacodynamics is the branch of Pharmacology that deals with the mechanism of action of a drug and the relation between the drug concentration and its effect. o It is the study of physical and chemical effects of drugs on the body, parasites and microorganisms. o What the drug does to the body is pharmacodynamics. For example, adrenaline acts on adrenal receptors, stimulates adenyl cyclase system producing effects such as cardiac stimulation and hyperglycemia is studied in Pharmacodynamics. 3. Therapeutics: o The branch of pharmacology that deals with the art and science of treatment of disease. It is the application of pharmacological information together with the knowledge of disease, for the prevention and cure of the disease. 4. Chemotherapy: o Chemotherapy refers to the treatment of diseases by chemicals that kill the cells, especially those of microorganisms and neoplastic cells. It is classified into two divisions: 5. Antibiotics o Includes the choice of drugs most potent against the organism or least toxic. Examples include Erythromycin given for gram positive organisms and Aminoglycans for gram negative organisms. 6. Toxicology:  NCM 106: PHARMACOLOGY o Toxicology is the branch of pharmacology which includes the study of adverse effects of drugs on the body. It deals with the symptoms, mechanisms, treatment and detection of poisoning caused by different chemical substances. o The main criterion is the dose. Essential medicines are poisons in high doses and some poisons are essential medicines in low doses. 7. Clinical Pharmacology: o Clinical pharmacology is the scientific study of drugs in man. It includes pharmacokinetic and pharmacodynamic investigations in healthy or diseased individuals. It also includes the comparison with placebos, drugs in the market and surveillance programmes. o The main objectives are: i. Maximize the effect of drug ii. Minimize the adverse effects iii. Promote safety of prescription o Aims include: i. Generate optimum data for use of drugs. ii. Promote usage of evidence based medicine. 8. Pharmacy: o Pharmacy is the branch of Pharmacology and is the art and science of compounding by dispensing drugs, preparing suitable dosage forms for administration to man and animals. The health profession blends health science with chemical science and effective use of drugs. 9. Pharmacognosy: o Pharmacognosy is the identification of drugs by just seeing or smelling them. It is a crude method no longer used. Basically it deals with the drugs in crude or unprepared form and study of properties of drugs from natural sources or identification of new drugs obtained from natural sources. 10. Pharmacoeconomics: o Pharmacoeconomics deals with the cost of drugs. In this discipline the cost of one drug is compared with another for the same use. The cheap drugs are preferred. 11. Pharmacogenetics: o Branch of pharmacology dealing with the genetic variations that cause difference in drug response among individuals or populations. o Example includes succinyl choline which is a skeletal muscle relaxant used in general anesthesia. It is metabolized by pseudocholinesterase and has a short duration of action. The presence of enzymes is determined by the gene and lack of this is recessively inherited. This may lead to respiratory paralysis, apnea and death. 12. Pharmacogenomics: o Pharmacogenomics is the broader application of genomic technologies to new drug discovery and further characterization of older drugs. o Recombinant DNA technology involves the artificial joining of DNA of one species to another. E. coli is mostly used. In this way we can get huge amounts of drug in purified form which is less antigenic.  NCM 106: PHARMACOLOGY o Examples include GH, interferon and vaccines. 13. Pharmacoepidemiology: o Pharmacoepidemiology deals with the effects of drugs on a large population. The effects may be good or harmful. It is conducted in three ways: i. Observational cohort studies ▪ Patients receiving drugs are collected and followed up to determine the outcomes. It is prospective (forward looking) research, however, is time consuming and lengthy. ii. Case control studies ▪ These are retrospective studies. They reverse the direction of scientific logic from forward looking to backward looking. iii. Phase trials ▪ These include different phases: ✔ Human pharmacology (20 to 50 subjects), pharmacokinetics and pharmacodynamics of the drug are observed ✔ Therapeutic exploration (50 to 300 subjects), drugs are compared with placebos ✔ Therapeutic confirmation (250 to 1000 subjects), safety, efficacy of drugs is compared with the drugs already present ✔ Therapeutic use (2000 to 10000 subjects), the opinion of physicians prescribing the drugs is collected regarding dosage and efficacy. Surveillance programmes are lengthy when conducted outside hospitals. 14. Comparative Pharmacology: o Branch of pharmacology dealing with the comparison of one drug to another belonging to the same or another group. 15. Posology: o Posology deals with the dosage of drugs. Example includes paracetamol given as one tablet of 500 mg thrice a day. 16. Animal Pharmacology: o Animal pharmacology deals with the different properties of drugs in animals. A vast variety of animals are utilized including rabbits, mice, guinea pigs, etc. Drugs are given to the animals and all parameters (their behavior, activites, vital signs, etc.) are recorded. Any change is noted down. If found to be useful in animals, then the drug is tested on humans.