Sources and Nature of Drug Dosage Form

INTRODUCTION

Pharmacology (derived from Greek words,pharmacon-drug; logos-discourse in) consistsof detailed study of drugs – its source, physicaland chemical properties, compounding,biochemical and physiological effects, pharmacodynamics(its mechanism of action),pharmacokinetics (absorption, distribution,biotransformation and excretion), therapeuticand other uses of drugs.According to WHO definition ‘Drug isany substance or product that is used orintended to be used to modify or explorephysiological system or pathological statesfor the benefit of the recipient’.Pharmacology has some major subdivisions:
Pharmacodynamics
 is the study of thebiochemical and physiological effects of thedrugs and their mechanism of action.
Pharmacotherapeutics
 deals with theuse of drugs in the prevention and treatmentof diseases and it utilizes or depends uponthe information of drug obtained by pharmacodynamic studies.
Pharmacokinetics
deals with thealterations of the drug by the body whichincludes absorption, distribution, binding/storage, biotransformation and excretion ofdrugs.
Toxicology
deals with the side/adverseeffects and other poisonous effects of drugs,since the same drug can be a poison,depending on the dose.
Chemotherapy
deals with the effects ofdrugs upon microorganisms and parasiteswithout destroying the host cells.Pharmacology also includes certainallied fields as:
Pharmacy
 is the science of preparation,compounding and dispensing of drugs. It isconcerned with collection, identification,purification, isolation, synthesis and standardizationof medicinal /pharmaceuticalsubstances.
Pharmacognosy
 deals with the study ofthe sources of drugs derived from plants andanimal origin.Chapter1.4Chapter1.1Sources and NatureofDrug Dosage Form