Topical Dosage Form

Topical dosage forms are applied to the skin or mucous membranes. Factors influencing drug absorption through the skin include chemical properties (oil content increases absorption), degree of skin hydration (moist skin enhances absorption), contact time (longer contact leads to more absorption), and skin integrity (abraded skin absorbs drugs more easily).

Topical preparations for the eye target the anterior eye segment, including the cornea, conjunctiva, sclera, iris, and ciliary body. Drug bioavailability in the eye is influenced by the tear film and cornea, with amphipathic drugs being more readily absorbed.

Inhalation topical dosage forms are administered via nasal or oral airways for local or systemic effects. Drug particles must be very small to reach the target organs, such as the lungs and bronchi, effectively.

Vaginal dosage forms include tablets, suppositories, gels, creams, or solutions. Solutions are less common due to short retention times. Semi-solid forms like gels and creams last longer, while tablets offer extended drug release due to mucosal adhesion. Vaginal suppositories (ovules) dissolve immediately upon application.

Suppositories are solid topical dosage forms molded to anatomical shapes for rectal application, producing local or systemic effects. The base melts or dissolves, distributing the active substance into the tissue.

Transdermal preparations facilitate the passage of active substances through the skin into systemic circulation to produce a systemic effect elsewhere in the body.