**2. Pharmacology**

Pharmacology is the science that deals with drugs, their properties, actions and fate in the body. It embraces the sciences of pharmaceutics (preparation of drugs), therapeutics (treat‐ ment of diseases by use of drugs) and toxicosis or adverse side-effects that arise from the therapeutic interventions. Pharmacology can be divided into the following processes:-

**i.** The pharmaceutical process of drugs; deals with chemical synthesis, formulation and distribution of drugs.

© 2013 Magoma; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

**ii.** Pharmacokinetic process; deals with the time course of drug concentration in the body.This process can be further subdivided into; absorption, distribution, biotrans‐ formation and excretion of the drug.

Parenteral Topical Oral

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Pharmaceutical dose form of a drug

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Pharmacokinetic, drug entry into systemic circulation

target site

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**Figure 1.** Relationships between the five pharmacological processes starting with the entry of the drug and ending

The drugs administered orally are absorbed at different sites along the gastrointestinal tract

Drug absorption is generally rapid because of the rich vascular supply to the mucosa and the ab‐ sence of a stratum corneum. Drugs delivered using this route are not exposed to gastric and in‐ testinal digestive juices and are not subjected to immediate passage through the liver. Therefore there is no prior biotransformation or first-effect before the drugs enter the systemic circulation.

Absorption depends on different factors such as pH, gastric emptying, intestinal motility and solubility of solid drugs. The rapidity with which a drug reaches the small intestine is enhanced when a drug is taken with water and when the stomach is relatively empty. However drugs

absorbed in the stomach and intestine are subjected to first-pass effect.

Pharmacodynamic, mechanism of drug action at

Therapeutic, clinical

response

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Toxicologic, adverse drug effects

**4.2. Oral administration**

*4.2.1. Oral mucosal or sublingual*

*4.2.2. Stomach and intestine*

(GIT):

with the clinical response and/or the toxic effects

