Semisolid dosage forms

Semisolid dosage forms

Introduction

Dosage forms that are in a plastic (i.e., change shape upon application of force), malleable semisolid state at room temperature include ointments, creams, gels, pastes, lotions, jellies, and foams. These semisolid prepara-tions may contain dissolved and/or suspended drugs. These preparations are designed to stay in physical contact with the surface of application for a reasonable duration of time, before they are inadvertently or intentionally removed or washed off. Their semisolid state and plastic rheological behav-ior is designed to aid their application to the target surface as a film. Many cosmetics would be considered semisolid.

Most of the semisolid formulations are used topically to deliver drugs to/through the skin. They can also be used for topical or systemic drug action in/through the eye, nose, ear, vagina, rectum, buccal tissue, or the urethral membrane. In addition, unmedicated semisolid formulations are frequently used as protectants or lubricants. Topical applications can be designed for either local effects or systemic absorption. For example, a topical dermatological product is designed to deliver a drug into the skin for treating dermal disorders. A transdermal product is designed to deliver drugs through the skin (percutaneous absorption) to the underlying tissue or the systemic circulation.

The major classes of agents that are used topically include corticoste-roids, antifungals, acne products, antibiotics, emollients, antiseptics, and local anesthetics. Topical agents are used as protectives, adsorbents, emollients, and cleansing agents.