Category: General pharmacology

The ultimate aim of pharmacological studies in animals is to find out a therapeutic agent suitablefor clinical evaluation in man. No doubt, animal studies provide analogies and serve as usefulmodels. The administration of biologically active agent to human beings is associated with anelement of risk, which cannot be predicted by even the most careful and…

A. Factors modifying the dosage and action of drugs :Individuals differ both in the degree and the character of the response that a drug may elicit andtherefore the optimum dose of a drug which produces the desired therapeutic effect varies fromperson to person. The important factors which influence the effect of a drug are: Drug…

Information about the time course of drug absorption, distribution and elimination(pharmacokinetics) can be expressed in mathematical terms and has contributed to ourunderstanding and planning of drug regimens. Pharmacokinetic principles aid in the selectionand adjustment of drug-dose schedules.Half life:Half life (t1/2) of a drug is the time taken for the concentration of drug in the blood…

) Physical state: Liquids are absorbed better than solids and crystalloids absorbed betterthan colloids.ii) Lipid or water solubility: Drugs in aqueous solution mix more readily than those in oilysolution. However at the cell surface, the lipid soluble drugs penetrate into the cell morerapidly than the water soluble drugs.iii) Ionization: Most of the drugs are organic…

It is the rate and amount of drug that is absorbed from a given dosage form and reaches thesystemic circulation following non-vascular administration. When the drug is given IV, thebioavailability is 100%. It is important to know the manner in which a drug is absorbed. Theroute of administration largely determines the latent period between administration…

) Iontophoresis: Galvanic current is used for bringing about the penetration of drugs intothe deeper tissue e.g. salicylates.ii) Inunctions: Absorbed when rubbed in to the skin e.g. nitroglycerin ointment in anginapectoris.iii) Jet injection: With help of high velocity jet produced through a micro fine orifice; Noneed of needle and therefore painless. e.g. mass inoculation programmes.iv)…

From the alimentary tract:(i) Buccal cavity: e.g. nitrates(ii) Stomach: e.g. aspirin, alcohol(iii) Intestine: e.g. most of non ionized and ionized drugs.(iv) Rectum: e.g. rectal suppositories, bisacodyl laxatives.Advantages of oral route: This route is safe, convenient and economical.Disadvantages of oral route: Onset of drug action is slow, irritant drugs cannot beadministered and it is not useful…

Pharmacokinetics deals with the absorption, distribution, metabolism and excretion drugs in thebody.A. Biotransport of drug: It is translocation of a solute from one side of the biological barrier tothe other. membrane proteins have many functions like (a) contributing structure to the membrane (b)acting as enzyme (c) acting as carrier for transport of substances (d) acting…

The activity of a drug is intimately related to its chemical structure. Knowledge about thechemical structure of a drug is useful for:(i) Synthesis of new compounds with more specific actions and fewer adversereactions(ii) Synthesis of competitive antagonist and(iii) Understanding the mechanism of drug action.Slight modification of structure of the compound can change the effect completely.

The exact relationship between the dose and the response depends on the biological objectunder observation and the drug employed.When a logarithm of dose as abscissa and responses as ordinate are constructed graphically,the “S” shaped or sigmoid type curve is obtained.The lowest concentration of a drug that elicits a response is minimal dose, and the largestconcentration…