ABSTRACT
A variety of pharmaceutical dosage forms are applied topically to the eye, nose, and ear which include solutions, suspensions, and ointments. In general, drugs are applied to the eye for the local effects of the medication, either on the surface of the eye or its interior. Amongst the various types of dosage forms for the eye, aqueous solutions are the most frequently used. In the extemporaneous preparation of ophthalmic formulations, one should consider sterility, preservation, isotonicity, pH and buffering, and viscosity. Nasal preparations are generally used for their decongestant activity on the nasal mucosa. Important considerations in the preparation of nasal solutions include isotonicity, pH and buffering, and viscosity. Ear preparations are also referred to as otic or aural preparations. Most of the official ear preparations are aqueous solutions of medications. They are used for treating mild infections, softening wax, cleansing after infections, drying wet surfaces, and as antiseptics. The important considerations in the formulation of otic products include pH and buffering. For example, an otic product with a pH value of less than 4 may cause burning and stinging sensation in the ear canal.
