Intro to PCOL

• Pharmacology deals with the interactions that exist between drugs administered with the living system or body.
• Pharmacology ensures the effective and safe use of medicines.
• Pharmacology is the study of how a drug affects a biological system.
• A drug is any chemical substance used in the diagnosis, treatment, and prevention of disease.
• Drugs are administered as different dosage forms such as capsules, tablets, syrups, elixirs, and solutions.
• Drugs are delivered through different routes of administration to enter the body.
• Oral Ingestion is the most convenient route and can be used for both solid and liquid dosage forms.
• A drug is ingested and passes through the GIT for absorption.
• The rate of absorption is greater in the intestine than in the stomach, primarily because of less mucous layer and larger surface area of the intestine.
• Gastric emptying, which takes about 4 hours, is important for intestinal absorption of a drug.
• Absorption most likely takes place in the small intestines.
• Sublingual Administration involves placing a drug underneath the tongue, dissolving, and absorbing through sublingual veins directly into the systemic circulation.
• Venous drainage from the mouth is to the superior vena cava which brings the drug into the systemic circulation.
• This route bypasses the hepatic circulation and protects soluble drugs from first-pass metabolism.
• Transdermal Absorption involves delivering a drug via a transdermal patch or as a solution for transdermal spray.
• Drug absorption via this route Transdermal Absorption is dependent on the surface area of application and lipid solubility of the drug.
• Drug absorption occurs at the lower rectal vault, bypassing hepatic circulation and is less predictable.
• Parenteral Injection routes bypass the GIT using drugs in solution, suspension, or emulsion forms.
• Subcutaneous (SC/SQ) route is where a drug is injected into the hypodermic layer of the skin and is only for non-irritating drugs.
• Rectal Administration is a route where a drug is administered as a suppository, inserted into the rectal vault and will dissolve at body temperature.
• Intradermal (ID) route is where a drug is injected in the dermal layer (beneath the epidermis) that produces an observable wheel on the skin’s surface.
• Topical Application is where drugs are applied to the mucous membrane where it will exhibit its local effects.
• Intrathecal (IT) route is where a drug is injected into the spinal subarachnoid space.
• Pulmonary Absorption is for drugs in gaseous or volatile forms that can be inhaled and absorbed through the pulmonary epithelium and mucous membrane of the respiratory tract.
• Application sites for Topical Application can be in the conjunctiva of the eye, nasopharynx and oropharynx, colon, vagina, urethra, and urinary bladder.
• Intramuscular (IM) route is where a drug is injected in the muscle belly, in limited amounts to avoid discomfort.
• Intravenous (IV) route is where a drug is injected into the vein producing rapid and complete bioavailability (100% BA) and is ideal for emergency cases as it provides rapid onset of action for the drug.
• This route is ideal for unconscious patients or for patients experiencing intractable vomiting.
• Factors that increase transdermal absorption include inflamed, abraded, burned, or denuded skin, high-lipid solubility, use of oily vehicle for the drug, and rubbing of the preparation into the skin.
• Hydration of the skin with an occlusive dressing can enhance transdermal absorption.
• Central compartment refers to the free drug, protein-bound drug metabolites, and biotransformation.
• A BASE in a ACIDIC medium is non-diffusible.
• Unwanted site of action is a site where the drug does not exert its therapeutic effect.
• Passive transport or diffusion is when a drug penetrates by diffusion and moves along the concentration gradient (high to low) by virtue of its solubility in the lipid bilayer.
• Absorption is the process of uptake of the compound from the site of administration into the systemic circulation.
• Tissue reservoirs are sites where the drug accumulates in the body.
• Cell membranes are semi-permeable and bulk flow of water can carry drug substances.
• Lipid solubility refers to the ability of a drug to dissolve in lipids.
• A weak acid in an acidic medium is non-ionized.
• Factors affecting drug absorption include lipid solubility, molecular size/weight of the drug, and degree of drug ionization.