General Pharmacology Lecture 2024 PDF

GENERAL PHARMACOLOGY S. K. AMPONSAH 11/06/24 S. K. AMPONSAH 1  PHARMACOLOGY Pharmacology is the science of how drugs interact with biological systems. It is a science that is basic not only to medicine but also to pharmacy, nursing, dentistr...

GENERAL PHARMACOLOGY S. K. AMPONSAH 11/06/24 S. K. AMPONSAH 1  PHARMACOLOGY Pharmacology is the science of how drugs interact with biological systems. It is a science that is basic not only to medicine but also to pharmacy, nursing, dentistry, and veterinary medicine. Pharmacology ranges from examining the effects of chemical agents on subcellular mechanisms, to treatment and prevention of major diseases. 11/06/24 S. K. AMPONSAH 2  Pharmacology Pharmacology unlocks the mysteries of drug actions, and also involves discovery of new therapies. Currently, novel pharmacological areas include genomic approaches to treatment. 11/06/24 S. K. AMPONSAH 3  Pharmacology Two important and interrelated areas under pharmacology are pharmacokinetics and pharmacodynamics. Pharmacokinetics deals with the absorption, distribution, and elimination of drugs. Pharmacodynamics is the study of the molecular, biochemical, and physiological effects of drugs on cellular systems. 11/06/24 S. K. AMPONSAH 4  DRUG AND DRUG PROPERTIES DRUG: A drug is any natural, semi- synthetic or synthetic chemical substance used in the diagnosis, prevention or treatment of disease or for other medical reasons. Is food a drug? Any good examples? 11/06/24 S. K. AMPONSAH 5  Sources of Drugs 1. Natural These are obtained from plants, microbes, animal tissues and minerals. One major compound found in plants that has pharmacological activity are alkaloids. Example of alkaloids used as drugs include morphine, cocaine, quinine and atropine. The antimalarial agent artemisinin is from the plant Artemisia annua. 11/06/24 S. K. AMPONSAH 6  Natural Several antibiotics have also been isolated from microorganisms such as Penicillium and Streptomyces species. Hormones are the most common type of drugs obtained from animals. Insulin used by diabetic patients are obtained from pig and cattle (Porcine and Bovine insulin respectively). Minerals are also obtained from the earth or soil (Iron and Potassium). 11/06/24 S. K. AMPONSAH 7 Example Drug Name Classification Magnesium Milk of Magnesia Antacid, Laxative Zinc Zinc Oxide Oint. Sunscreen, Skin protectant Lithium Lithium Carbonate Antidepressant Iron Ferrous sulphate Anti-anemic 11/06/24 S. K. AMPONSAH 8  Natural Vitamins are also from natural substances ie plants. Your body needs these vitamins to grow, develop, and function normally. A well-balanced diet usually provides all of the vitamins required. 11/06/24 S. K. AMPONSAH 9  Natural sources However, there are times, such as during pregnancy and childhood, when your body needs more vitamins than usual. Certain illnesses occur as a result of your body not getting efficient amount of vitamins it needs e.g night blindness, scurvy, and pellagra. 11/06/24 S. K. AMPONSAH 10  2. Synthetic The rise of modern chemistry has enabled scientist to synthesize new compounds. Aspirin and a procaine (local anesthetic) were amongst the first to be synthesized in the lab. Scientist have developed new drugs based on advances technology that model drug receptors. 11/06/24 S. K. AMPONSAH 11  Synthetic This facilitates the design of drug structures that best fit the 3D receptor conformation. Other examples of synthetic drugs include; paracetamol and phenytoin (anticonvulsant). 11/06/24 S. K. AMPONSAH 12  3. Semi-synthetic It is a chemical synthesis that uses compounds isolated from natural sources (e.g. plants or bacterial or cell cultures) as starting material. Semi-synthetic drugs are made if the natural molecule is structurally complex or difficult to be produced by total synthesis. The antimalarial drug artemether (a component of Coartem) is a semisynthetic agent derived from naturally occurring artemisinin. 11/06/24 S. K. AMPONSAH 13  Semi-synthetic Most often they are a modification of naturally occurring drugs. Their structure has other groups added to existing natural occurring compounds. Other examples include heroine from morphine, homatropine from atropine. Sometimes animal insulin are changed into human insulin. 11/06/24 S. K. AMPONSAH 14  DRUG NOMENCLATURE Drugs can be classified by one of these 3 names;  Chemical: a long name that refers to the chemical structure of the drug  Generic: a shorter preferred name, derived from the chemical name  Trade/brand name: assigned by manufacturer of the drug 11/06/24 S. K. AMPONSAH 15  Drug nomenclature Chemical name: Gives exact chemical composition of the drug Can also be the IUPAC name of the drug Generic (non-proprietary) name: Typically derived from chemical name Usually shorter Given by the United States Adopted Names Council 11/06/24 S. K. AMPONSAH 16  Drug nomenclature Trade (proprietary) name This name is registered by the drug manufacturer. Followed by the trademark symbol ®. This name can only be used by the manufacturer. 11/06/24 S. K. AMPONSAH 17  Examples CHEMICAL NAME GENERIC NAME BRAND NAME N-acetyl-p-aminophenol Acetaminophen Tylenol, Panadol etc 7-chloro-1-methyl-5-phenyl- Diazepam Valium 3H-1,4-benzodiazepin- 2[1H]-one 11/06/24 S. K. AMPONSAH 18  DRUG PREPARATIONS/FORMULATI ONS Drugs are seldom administered in pure form. They are made into various dosage forms to facilitate administration and ensure safety and efficacy. A dosage form is a system or device by which the drug is delivered to the body. In a dosage form, the active ingredient is combined with inert ingredients that facilitate administration of the drug. 11/06/24 S. K. AMPONSAH 19  Drug formulation Dosage forms often have;  Excipients—Excipients are inactive substances used as carrier for the active ingredient.  Binders—Binders promote adhesion of active and inactive ingredients in tablets.  Diluents—Diluents are additives used to increase the bulk weight or volume of a dosage form.  Preservatives—Preservatives are substances that prevent or minimize the growth of bacteria or other microorganisms. 11/06/24 S. K. AMPONSAH 20  Drugs formulation Drugs can be prepared as;  Solid dosage forms  Semi-solid dosage forms  Liquid dosage forms 11/06/24 S. K. AMPONSAH 21  SOLID DOSAGE FORM Solid dosage forms include tablets, caplets, capsules, lozenges, granules and powders. Solid dosage forms offer a number of advantages which include:  Good stability  Ease of packaging  Ease of dispensing 11/06/24 S. K. AMPONSAH 22  Solid dosage form Solid dosage forms also allow for accurate dosing. The entire dose is contained within the contents of the solid dosage form, which minimizes measuring errors. Solid dosage forms may, however, be difficult to swallow, have a slow onset of action, and may be degraded by the acidic contents in the stomach. 11/06/24 S. K. AMPONSAH 23  1. Tablet/caplet Tablets are available in variety of sizes, shapes, colors, and thicknesses. They are produced by compression, and are composed of one or more active ingredients and one or more inert substances. Some pharmaceutical manufacturers produce a hybrid of tablet and capsule called caplets. 11/06/24 S. K. AMPONSAH 24  Caplets Caplets are shaped like capsules. They are often easier to swallow than large tablets, and are more stable than capsules. 11/06/24 S. K. AMPONSAH 25  Tablets Tablets can be scored so they may be easily broken in halves or quarters. Some are also designed to be chewed (chewable tablets) and often contain a base that is flavored or colored. Tablets can be formulated with delayed release characteristics to allow for less- frequent dosing and/or side effects. 11/06/24 S. K. AMPONSAH 26  Tablets Some tablets may have a coating (enteric coated) applied to the outside to mask unpleasant flavor or odor. They are also meant to protect the drug from stomach acid or to protect the stomach lining from the drug. Enteric coated tablets should not be chewed or crushed. 11/06/24 S. K. AMPONSAH 27  Tablets Some tablets are also film- coated. They are coated with a thin outer layer of water-soluble material that dissolves rapidly in the stomach. The coating is designed to cover the unpleasant taste or odor of the medication. Coating also protects drugs from deterioration due to air and light. 11/06/24 S. K. AMPONSAH 28  2. Capsules Capsules are a solid dosage form in which the drug is enclosed within a hard or soft gelatin shell. The gelatin shell dissolves in the stomach, releasing the drug. The gelatin shell may be transparent, semitransparent, or opaque. 11/06/24 S. K. AMPONSAH 29  Capsules A capsule may contain powders, granules or liquids with one or more active ingredients and one or more inert ingredients. Capsules can be formulated with delayed- release characteristics to allow for less- frequent dosing and/or side effects. 11/06/24 S. K. AMPONSAH 30  3. Lozenges Lozenges, also known as troches or pastilles, are hard, oval, or discoid solid dosage forms with a flavored sugar base. They are dissolved in the mouth and generally have local therapeutic effects. Over-the-counter lozenges for relief of sore throat are a common example of this dosage form. 11/06/24 S. K. AMPONSAH 31  4. Powders and granules Powders are finely ground dry drugs that can be used topically (athlete’s foot) or administered orally. Granules are larger than powders, and generally more stable than powders. Drug granules 11/06/24 S. K. AMPONSAH 32  5. Suppositories A suppository is designed to be inserted into the rectum (rectal suppository) or vagina (vaginal suppository) The suppository base is an inactive ingredient, which melts or dissolves in the body cavity, releasing the medication. 11/06/24 S. K. AMPONSAH 33  Suppository Some suppositories are designed for local action, while others are used as vehicles for systemic drugs (analgesics). Suppositories are often used in children and in adults who are unable to take oral medications. 11/06/24 S. K. AMPONSAH 34  SEMI-SOLID DOSAGE FORM Semisolid agents are different in their composition from liquids or solids. They are usually intended for topical application. They may be applied to the skin, placed on mucous membranes, or used in the nasal, rectal, or vaginal cavity. Examples include creams, lotions, gels and pastes. 11/06/24 S. K. AMPONSAH 35  1. Creams A cream is an example of an oil-in-water (O/W) emulsion, because it contains a small amount of oil dispersed in water. They are mostly intended for external use. Creams can be easily massaged into the skin, without leaving an oily residue. Creams can also be formulated for vaginal or rectal use. 11/06/24 S. K. AMPONSAH 36  2. Lotions A lotion is an O/W emulsion that is thinner than a cream. Lotions often contain more water than creams. Lotions penetrate into the skin and can cover large areas without leaving an oily residue. 11/06/24 S. K. AMPONSAH 37  3. Gels A gel contains solid medication particles, like a suspension, in a thick liquid. It can be used internally and externally. The particles in a gel are ultrafine and are linked to form a semisolid material. Gels can penetrate the skin without leaving a residue. 11/06/24 S. K. AMPONSAH 38  4. Paste A paste contains more solid material and less liquid base. Pastes are stiffer, less greasy, and applied more thickly. 11/06/24 S. K. AMPONSAH 39  LIQUID DOSAGE FORM Solutions and suspensions are the most common liquid formulations. They can be administered by oral, parenteral (injectable) or other routes of administration. They provide a convenient means of administering drugs to pediatrics and other patients who cannot swallow solid forms. Less convenient because liquid would have to be measured anytime dose is to be given. 11/06/24 S. K. AMPONSAH 40  Solutions and suspensions Solutions and suspensions for oral administration are often sweetened and flavored to increase palatability. Sweetened aqueous solutions are called syrups. Sweetened aqueous-alcoholic solutions are known as elixirs. The alcohol in elixirs are added when the drug is not sufficiently water-soluble. 11/06/24 S. K. AMPONSAH 41  Solutions and suspensions Sterile solutions and suspensions are available for parenteral administration (injections). They come with a needle and syringe or with an intravenous (IV) device. Some are also formulated into sterile powders with sterile liquids that have to be mixed before injected. This is because the drug is not stable for long in solution. 11/06/24 S. K. AMPONSAH 42  Injectable drug solutions 11/06/24 S. K. AMPONSAH 43  IV infusions 11/06/24 S. K. AMPONSAH 44  Solutions and suspensions There are also sterile ophthalmic solutions and suspensions. They are made with a dropper which is to be instilled into the conjuctival sac. 11/06/24 S. K. AMPONSAH 45  Ophthalmic solution 11/06/24 S. K. AMPONSAH 46