Introduction to pharmacology & therapeutics

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Introduction to pharmacology & therapeutics:

Introduction to pharmacology & therapeutics Presented by: Dr. Shamima Sultana M.B.B.S., M.Phil (Pharma), Lecturer, M.M.C. Composed by: Muhammad Syeef Khalid M#44, M.M.C.

Some definitions:

Some definitions Pharmacology: Greek word → ‘Pharmacon’ means drugs ‘Logos’ means Knowledge/science So, it means “Scientific study of drugs & the interactions of drugs with the living system.” #It includes: History Dosage formulations Source Route of administrations Physical & chemical Absorption properties Distribution [Contd…]

Contd…:

Contd… Mechanism of action Excretion Phisio-chemical effect Clinical uses/indications effect in the body Adverse effects of drugs Biotransformation

Branches of pharmacology:

Branches of pharmacology Pharmacokinetics Pharmacodynamics Experimental pharmacology Clinical pharmacology Pharmacy Toxicology Pharmacognosy Posology Pharmacotherapeutics Pharmacogenetics

PHARMACOKINETICS:

PHARMACOKINETICS ‘Pharmacon’ means Drugs. ‘Kinesis’ means movement. In a word it means what body does to the drug. It includes absorption, distribution, biotransformation & excretion.

PHARMACODYNAMICS:

PHARMACODYNAMICS ‘Pharmacon’ means Drugs. ‘Dynamic’ means power. In a word it means what drugs do to the body. It includes mechanism of action & pharmacological effects of drugs.

CLINICAL PHARMACOLOGY:

CLINICAL PHARMACOLOGY Scientific study of drugs in human beings. Human trials or clinical trials of drugs on human being. Clinical administrations of drugs in man. EXPERIMENTAL PHARMACOLOGY Experimental study of drugs in test animals.

PHARMACY:

PHARMACY Deals with preparation, formulation & dispensing of drugs. It also includes dosage formulations of drug suitable for administration. TOXICOLOGY Deals with poisons, poisoning & treatment. It is usually studied in forensic medicine.

PHARMACOGNOSY:

PHARMACOGNOSY Deals with botanical sources of drugs, their identification, cultivation, purification & isolation from the plants. PHARMACOTHERAPEUTICS Deals with science & art of use/application of drugs for diagnosis, prevention & treatment of diseases. PHARMACOGENETICS Concerned with drug responses governed by heredity. POSOLOGY Study of doses of drugs.

Drugs:

Drugs Definition: French word ‘Drogue’ means dry herb. “A drug is any substance or product that is used or intended to be used to modify or explore physiological systems or pathological states for the benefit of the recipient.” “Benefit of the patient”: # For diagnostic purpose:e.g. Barium meal x-ray. Barium enema. # For treatment purpose:e.g. Metronidazole in amoebiasis. Contd…

“Benefit of the patient” (Contd)::

“Benefit of the patient” (Contd): # For preventive or prophylactic use:e.g. Polio vaccine in prophylaxis of poliomyelitis. # For control:e.g. Insulin for control of Diabetes melitus.

Medicine:

Medicine Definitions: Any drugs or combination of drugs supplied in a suitable container with a proper labeling having a definite dosage form with dose & are therapeutically used for treatment of diseases. e.g. Ranitidine for peptic ulcer. All medicines are drugs But All drugs are not medicines.

Difference between drug & food:

Difference between drug & food Drug Food 1.Alters body function. 1.Maintains body function. 2.No calorie value. 2.Have calorie value. 3.Excretion must occur. 3.Stored in the body.

Prodrug:

Prodrug Definition: Some drugs do not produce any pharmacological effects until they are chemically altered within the body. e.g. Prodrug Active drug Oxazepam Diazepam Protonsil Sulphonamide Talampicillin Ampicillin Aims & advantages of use of prodrug: ↑Absorption from the site of administration. Avoid first pass metabolism. ↓Local adverse effects of drugs.

Essential Drugs:

Essential Drugs The drugs that Satisfy health care needs of majority of population. Always available in adequate amounts & appropriate dosage forms. Economic/cheap. Example: Paracetamol Antacid Vitamin Ors Iron tablets Histamin

Pharmacopoeia:

Pharmacopoeia Greek ‘Poein’ means ‘preparation of drugs’. It is a book containing a list of drugs wiith descriptions, tests & formulas for preparing the drugs. e.g. B.P.,U.S.P.,European P., Indian P. We usually follow B.P.,U.S.P. (sometimes). Pharmacological Effects Physiological &/or biochemical changes in body produced by a drug in therapeutic concentration.

Potency:

Potency It is the comparative measure of different doses of two or more drugs needed to produce same effect. The drug which act at lower conc. is more potent .e.g. to relieve pain morphine & pathedine are used.To release pain pathedine is 10 times less potent than morphine.ie, pathedine requires 10 times more dose than morphine to release the pain. So, potency of morphine is 1 & that of pathedine is o.1. Potent drug acts at lower concentration.

Some definitions:

Some definitions Affinity: Tendency of a drug to bind with a receptor is termed as affinity. Efficacy: Ability of a drug to produce (maximum) pharmacological effect combining with a receptor. Agonist: A drug having both affinity & efficacy for receptor. Agonist = Affinity+Efficacy e.g. morphine is an agonist for opoid receptor. Partial agonist: Drug combining with its specific receptor & evokes a week response. (submaximal effects & intermediate efficacy) i.e. Affinity +low efficacy. E.g. Nalorphine is partial agonist of opioid receptor.

Some definitions (Contd…):

Some definitions (Contd…) Antagonist: The drug that combines with its specific receptor & produce no response.i.e. Antagonist = Affinity + No efficacy. e.g. Atropine is the muscarinic antagonist of cholinoceptor. Inverse agonist: Some drugs bind with receptors & effect opposite to those produced by true agonist. e.g. Benzodizepines β – carbolines *Sedation *Anxiolysis *Muscle relaxation *Control convulsion. *Stimulation *Anxiety * ↑Muscle tone *↑Convulsion.

Absorption:

Absorption Definition: Absorption is the process by which a drug gets into systemic circulation by crossing the biological membrane or barrier from its site of administration. After oral administration, a drug must cross the intestinal epithelium & after or intramuscular injection, they must cross capillary walls to reach the circulation. Passage of drugs across body membranes: * Because of lipid nature, the cell membrane is highly permeable to lipid substances. * As cell membrane has pores or channels it may allow passage of small lipid insoluble molecules. * Water & urea (small lipid-insoluble compounds) also readily enter the cells.

Processes of absorption:

Processes of absorption Passive process: Passive diffusion(99%) Filtration (insignificant) Specialized transport/Active process: Active transport Facilitated diffusion Pinocytosis.

Receptors:

Receptors Definition: Macromolecular structure, lipoprotein in nature, present in cell membrane or inside the cell with which drug binds reversibly or irreversibly & may or may not produce pharmacological effects. Classification of receptors : # According to molecular structure, nature & transduction mechanism ,receptors are of 4 types: 1.Ultrashort acting/Type ا /Fast receptor/Channel linked receptor: Directly coupled to an ion channel & effects within a few milliseconds after binding with agonist. e.g. Nicotinic cholinoceptor GABA receptor Glutamate receptor.

Receptors (contd…):

Receptors (contd…) 2.Short acting/Type اا /Slow receptor/G-protein coupled receptor: Coupled to effector systems via G-protein & acts within few seconds. e.g. Muscarinic cholinoceptor Adrenoceptor ( α , β ),etc. *G-protein acts as intermediate between receptor & enzyme located on cytoplasmic surface of plasma membrane.

Receptors (contd…):

Receptors (contd…) 3. Intermediate acting/Type اااا /Kinase linked receptor: Responds within few minutes. e.g. Receptors for insulin & growth factors receptor. 4. Long acting/Type ا V/Nuclear receptor: Effects occur within hours or days. e.g. Steroid receptor Thyroid hormone receptor. # According to function: Active receptor (1-2%) e.g. Adrenoceptors ( α , β ). Spare/surplus receptor:Remain inactive but produce effect after saturated by drugs.e.g.insulin receptor. Silent receptor:Don’t produce any effect & act as store house. .e.g.plasmaprotein.

Receptors (contd…):

Receptors (contd…) #According to specific activity: Cholinoceptors e.g. .Muscarinic & nicotinic receptors. Adrenoceptors e.g. α , β . Histamine receptors. Dopamine receptors. 5-HT receptors. Opioid receptors.