JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD Pharm. D III Year PHARMACEUTICAL FORMULATIONS Previous Question Paper (April/May - 2019 - R08)

Suppositories are solid dosage forms intended for insertion into body cavities (rectum, vagina, or urethra) where they melt, soften, or dissolve to exert local or systemic effects. They are designed to be stable at room temperature but liquefy at body temperature.

Suppository bases are classified into two main categories:

1. Fatty or Oleaginous Bases: These include Theobroma oil (cocoa butter), which melts at 30-35°C, and synthetic triglycerides. They are popular due to their ability to melt rapidly at body temperature, though they may become rancid over time.
2. Water-Soluble or Water-Miscible Bases: These include Glycerinated gelatin and Polyethylene glycols (PEGs). Glycerinated gelatin is commonly used for vaginal suppositories, while PEGs are synthetic polymers available in various molecular weights that dissolve in body fluids rather than melting, allowing for a slower release of the drug.

Ophthalmic ointments must be sterile to prevent ocular infections. Since these formulations are typically anhydrous and viscous, conventional aqueous sterilization methods are often unsuitable. The following methods are employed:

1. Dry Heat Sterilization: The base (e.g., white petrolatum and liquid paraffin) is sterilized by heating in a hot air oven at 160°C for 2 hours. This is the most common method for heat-stable ointment bases.
2. Filtration: If the drug is heat-labile, it is dissolved or suspended in a sterile vehicle. The vehicle itself may be sterilized by membrane filtration (0.22 µm pore size) before being incorporated into the sterile base under aseptic conditions.
3. Aseptic Processing: The entire preparation process, including the incorporation of the drug into the sterilized base, is carried out in a laminar air flow hood using sterile equipment and containers to prevent microbial contamination.
4. Radiation: Gamma irradiation may be used for certain heat-sensitive drugs, provided the drug and the base are compatible with the radiation dose required for sterilization.