Vagina physiology

A number of excellent articles have been published detailing the anatomy and physiology of the human vagina [1-4], and therefore only a brief overview is provided here. 

ANATOMY AND PHYSIOLOGY OF THE VAGINA RELEVANT TO DRUG DELIVERY... 

Tablets are flat with an oval-, pear-, or bullet-shape to facilitate the insertion into the vagina but often present a hard surface and dried ingredients that may cause undesirable irritations on the other hand, pessaries are characterized by a smooth surface and by excipients dissolving or melting in physiological conditions, but they are messy to apply and undergo leakage.

Monkeys, in particular Rhesus macaque and squirrel monkey, have been considered as models for vaginal drug absorption because of the similarities between nonhuman primate and human anatomy. The vagina of rhesus macaques is characterized by connective tissue attachments, localization of steroid hormone receptors, duration, and cyclic changes in vaginal physiology similar to that of humans [119]. 

This article describes the physiology of the human vagina, its characteristics of absorption, and its permeability. The reader will also be familiarized with current research trends in vaginal delivery and absorption of drugs. 

Kistner, R. Physiology of the vagina. In The Human Vagina, North Holland Publishing Co. New York, 1978 109-120. 

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