Vaginal drug delivery types

These factors become particularly important for preparations intended for long-term vaginal administration. Formulation factors which affect vaginal drug delivery which are common to the various types of vaginal dosage forms include ... 

During oral drag absorption, metabolism can occur in the enterocyte cells that line the lumen of the intestine and in the liver before a drug enters the systemic circulation. Loss of drug in either of those locations constitutes first pass elimination . This first-pass effect can be observed for any type of extravascular delivery (nasal, pulmonary, rectal, vaginal, etc.). The magnitude of the first-pass elimination can be quite different in different tissues. However, the most common site for first-pass metabolism is the gut and liver. Once a drug enters the systemic circulation, most of its metabolic elimination occurs in the liver. Consequently, much of the literature on metabolism centers on hepatic metabolism. 

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