PHAR 4634 - Chapter 7 Page 6

Inhalation

Local effect - bronchodilators

Systemic effect - general anesthesia

Rapid absorption, by-passing the liver

Absorption of gases is relatively efficient, however solids and liquids are excluded if larger than 20 micron and even then only 10 % of the dose may be absorbed. Cromolyn is taken as a powder with 50 % of the particles within the range of 2 to 6 micron. Larger than 20 micron and the particles impact in the mouth and throat. Smaller than 0.5 micron and they aren't retained.

Topical

Local effect - eye drops, antiseptic, sunscreen, callous removal, etc.

Systemic effect - e.g., nitroglycerin ointment.

Absorption through the skin, especially via cuts and abrasions but also intact, can be quite marked. This can be a real problem in handling toxic materials in the laboratory or pharmacy.

Other ROA's

Other routes of administration include: intra-nasal, some systemic absorption has been demonstrated for propranolol and some low dose hormones; intra-arterial for cancer chemotherapy to maximize drug concentrations at the tumor site; and intrathecal directly into the cerebrospinal fluid.

This page was last modified: 12 February 2001