Purpose of medication
Medication is a substance administered for the diagnosis, cure, treatment, or relief of a symptom or for prevention of disease.
Words like medication and drug are generally used interchangeably.
Crude drugs, such as opium. Castor oil, and vinegar, were used in ancient times.
The written direction for the preparation and administration of a drug is called a prescription.
· For treating diseases
· For cure and treatment
· Relief of symptoms
· To promote health : drugs arc given to the individual to increase the resistance eg. Vitamins
· To prevent diseases e.g. Vaccines and antitoxins
· To diagnose diseases e.g. Barium used in X ray studies
· To alleviate diseases: certain drugs are given for the palliative effect or for the temporary relief of symptoms but does not remove the cause or cure the disease e.g. Analgesics
· For cure and treatment:
▪ By restoring normal functions e.g. Digoxin
▪ By supplying a substance that is deficient in the body e.g.lnsulin
▪ By destroying the causative organisms e.g. Quinine in malaria
▪ By counteracting with the toxic substances circulating in the body e.g.. Antidotes
▪ By stimulating lhc functions of an organ or a system e.g. Stimulants
▪ By depressing thc functions of an organ or a system e.g. Sedatives
Four kinds of names: its generic name, official name, chemical name, and trademark or brand name.
Generic nameis given before a drug becomes officially an approved medication.
The chemical nameis the name by which a chemist knows it; this name describes the constituents of the drug.
Trade nameis the name given by the drug manufacturer. The name is usually selected to be short and easy to remember. Sometimes called the brand name. For Example, the drug hydrochlorothiazide (official name) is known by the trade names Esidrix and hydrodiuril.
Principles of drug action:
Pharmacokineticsis the process by which a drug moves through the body and is eventually eliminated.
Pharmacodynamicsrefers to the physiologic and biochemical effects of a drug on the body. Understanding these processes helps in evaluating therapeutic and adverse effects of medications.
Pharmacokinetics involves the absorption, distribution. Metabolism and excretion of a medication. Each medication has its own characteristic rate and manner by which it is absorbed by body tissues, delivered to reactive cells, transformed to harmless substances, and removed from the body.
Absorption is the process by which a medication enters the blood stream. The route of administration affects how quickly and completely a medication is absorbed. IV (Intravenous) administration offers the quickest rate of absorption followed in descending order by IM (intramuscular), Subcutaneous and PO (per oral) routes.
Distributionis -the process by which the medication is delivered to the target cells and tissues. The effectiveness of the circulatory systeme, the amount of medication bound to protein, and the tissue specificity of the drug affects distribution.
Metabolism– Is the process of chemically changing the drug in the body. Metabolism takes place mainly in the liver. Alterations in. Liver function, including decreased function that occurs with aging or disease affects the rate at which drugs are, metabolized.
Excretionis the process of removing the drugs or its metabolites from the body. The kidneys excrete most drug metabolites. Some excretion also occurs in the lungs and the intestines. Decreased kidney function adversely affects drug excretion.
Drug activity is the result of chemical interactions between a medication and the body’s cells to produce a biological response. Most drugs interact with a cellular component to initiate a series of biochemical and physical changes, resulting in the drug’s effects. These biological and physical effects can be local or systemic. For example, local effects are seen When moisturizing lotion is applied to chapped skin.
Systemic effects can affect one or more body systems. For e.g. When analgesics (pain medications) are administered, effects on sedation (nervous system,) respiratory rate and depth (lungs) and constipation (gastrointestinal tract) are seen.