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PharmD clinical pharmacy program Level 3, Semester 2 Biopharmaceutics & Pharmacokinetics (PT608(

Extravascular routes

Extravascular administration can be by several routes:

▪ Oral administration (tablet, capsule, suspension, etc.)

▪ Intramuscular administration (solution and suspension)

▪ Subcutaneous administration (solution and suspension)

▪ Sublingual or buccal administration (tablet)

▪ Rectal administration (suppository and enema)

▪ Transdermal drug delivery systems (patch)

▪ Inhalation (metered dose inhaler).

Important features of extravascular routes of drug administration

1. An absorption phase is present.

2. The onset of action is determined by factors such as formulation and type of dosage

form, route of administration, physicochemical properties of drugs, and other

physiological variables.

3. The entire administered dose of a drug may not always reach the general circulation

(i.e. incomplete absorption).

 The differences in the onset of action, termination of action, and duration of action

are due to the differences in the absorption characteristics of a drug owing to

formulation differences. One may observe similar differences in the absorption

characteristics of a drug when it is administered via different dosage forms or

different extravascular routes.

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