Drugs
A substance which is used to or intended to be used to modifying or exploring any physiological change or pathological state withtin the recipient is known as drugs.
Types #
17/2/2023
Based on root of administration #
Oral- swallowed
Oral- sublingual
Rectum
Epithelial
Perental: Intravenous administration directly into the blood stream
Based on therapeutic effect #
Anti arhythmics: drugs that are used for treating heart beat
Anti anginals : used for treatment chest pain due to reduced blood flow.
Vasodialotors : used for relaxing and opening blood vessels
Cardiotonics: drugs used for improving the contraction of heart muscle
Hypocholestermic: used to reduce the level of cholesterol.
Anti allergic : used to treat unwanted reactions to the body
Drugs for gastrointestinal intestinal track
Drugs for renal function
Drugs for central nervous system
Drugs for peripheral nervous system
Based on chemical structure #
Hydrocarbons
Halogenated compounds
Alcohols
Carboxylic acids
Phenols
Amides
Amines
Sulphones, sulphonides, thiourea
Pharrmacology #
Pharmacology refers to the branch of medicine that deals with the interaction of drugs with living systems and different processes within them. It can be also called as the mechanism of drug action. However, the mechanism or mode of drug action may contain an additional stage known as pharmaceutical phase.
Pharmacology consists of two stages:
Pharmacokinetics: it is referred to as the action of the body on the drug and it consists of 4 different processes
Absorption: it is the process by which drugs enter the body. Whatever root of administration may be used, the drug should cross all the tissue membranes (skin, epithelium subcutaneous, capillary wall) to enter the blood flow.
Digestion: it refers to the movement of the drug around the body. After entering the blood, the drug molecules must reach the targeted cells. In most cases, blood is the medium of distribution.
Metabolism: it is the process by which drugs are biochemically altered to make them sufficiently water soluble for excretion with urine or stool. This process takes place in multiple organs such as liver, gut wall, kidney, intestine, skin.
Excretion: it is the process by which the drugs and its products after metabolism leave the body. Water soluble drugs do not undergo much metabolism and are excreted through urine. Lipid soluble drugs are converted into water soluble products and then excreted via kidney or via Bile.
Pharmacodynamics: it is the mechanism where drugs exert their effects on the body which includes therapeutic effect or toxic effects when the drugs interact with the receptors present in the body. In short, pharmacodynamics can also be called as drug receptor interaction. There is a direct correlation between drug concentration and its effects. Pharmacodynamics refers to the relationship of drug concentration at the site of action and the resulting affect. It also includes the time course and intensity of the therapeutic or toxic effects. Drug usually works by binding to a receptor and producing desired effects. The concentration of the drug at the receptor site determines the intensity and the effect of the drug. Other factors included in pharmacodynamics:
Mechanism by which signal is translated into cell by secondary messages
Gene translation and protein synthesis for producing therapeutic/ toxic effects.
Some important terms #
t_1/2Half life: it is defined as the time required for the plasma concentration of a drug to be reduced by 50% of its initial concentration.
ED_50 effective dose: The dose of the drug that is effective for a 50% of the population exposed to the drug.
LD_50 Lethal dose: the drug dose which causes death in 50% of the population is known as LD_50
Drug bioavailable: it refers to the extent of a substance or a drug that becomes completely available to the intended biological destinations. It is defined as the measure of rate or fraction of the initial dose that successfully reaches the intended destination. The absolute bioavailability of a drug administered by any extra vascular method is generally less than 1.
The factors which effect the bioavailability are:
Root of administration
With or without food.
Influence of other drugs
Metabolism rate of the individual
Age or diseased state.
Drug receptor interaction: #
The drug receptor interaction can be explained on the basis of lock and key mechanism. The receptors present in the body are made up of different kinds of proteins. Depending upon the nature of protein, the receptors can have cavities of domains of different sizes and shapes present in them.
- Drugs need to be modified according to the receptors. Amoxylin vs. Penicillin
Vitamins #
They are organic compounds complexes with metals and are necessary for normal functioning of living organisms but are not synthesized within the living organisms.
- Water soluble vitamins: vitamin B,C
- Fat soluble: A,D,E,K
- Water and fat insoluble: vitamin H (biotin)