ABSTRACT
Clinical pharmacology and paediatric medicine usually focus on the drug substance (active ingredient) and less frequently on the drug preparation and its other ingredients. However, pure drug substances are rarely administered to patients but are presented as dosage forms suitable for the intended route of administration, for example tablets, capsules and liquids for oral administration; injection solutions or powders to be reconstituted for injection; pressurised inhalers and nebuliser solutions for administration into the lung. The route of administration may be determined by the physical and chemical characteristics of the drug; the characteristics of the patient and of their illness. Thus, intravenous injections will be preferred for treatment of life-threatening infections or for drugs poorly absorbed from the gut whilst the convenience of oral administration will be preferred for management of a long term illness such as epilepsy.
