Biomaterial Database

A method to measure the solubility of drugs in ointment bases. 1998

N Kobayashi, and I Saitoh

Development Research Laboratories, Shionogi & Co., Ltd., Hyogo, Japan.

The solubility of a drug in an ointment base is an important factor determining the efficacy of the formulation. However, it is difficult to measure the solubility of drugs in ointment bases. Thus, a rapid and simple method to determine the solubility of drugs in ointment bases was investigated. Using oxybenzone as a model drug, the bleeding liquid which leaked out from various ointments was collected, and the drug concentration in the bleeding liquid was measured. The drug concentrations in the bleeding liquid collected from soluble type ointments in which the drug is dissolved in bases were in accord with that in the ointments. On the other hand, the drug concentrations in the bleeding liquid collected from crystal dispersion type ointments in which drug crystal are dispersed in bases were the same in spite of the variance in total drug concentrations in the ointments. It was confirmed by microscopic examination that crystals do not flow out into bleeding liquid in the crystal dispersion type ointment. It was also confirmed that the solubility of the drug obtained in the present study was in a solubility range consistent with microscopic examination. Furthermore, an increase in the drug solubility was detected by this method when the drug solubility in the base was raised by adding a detergent into the base. And the results from this method were in accord with the results from microscopic examination. These results suggest that the drug concentration in bleeding liquid represents the solubility of the drug in an ointment.

UI	MeSH Term	Description	Entries
D007202	Indicators and Reagents	Substances used for the detection, identification, analysis, etc. of chemical, biological, or pathologic processes or conditions. Indicators are substances that change in physical appearance, e.g., color, at or approaching the endpoint of a chemical titration, e.g., on the passage between acidity and alkalinity. Reagents are substances used for the detection or determination of another substance by chemical or microscopical means, especially analysis. Types of reagents are precipitants, solvents, oxidizers, reducers, fluxes, and colorimetric reagents. (From Grant & Hackh's Chemical Dictionary, 5th ed, p301, p499)	Indicator,Reagent,Reagents,Indicators,Reagents and Indicators
D009823	Ointment Bases	Various mixtures of fats, waxes, animal and plant oils and solid and liquid hydrocarbons; vehicles for medicinal substances intended for external application; there are four classes: hydrocarbon base, absorption base, water-removable base and water-soluble base; several are also emollients.	Bases, Ointment
D003313	Zea mays	A plant species of the family POACEAE. It is a tall grass grown for its EDIBLE GRAIN, corn, used as food and animal FODDER.	Corn,Indian Corn,Maize,Teosinte,Zea,Corn, Indian
D004364	Pharmaceutical Preparations	Drugs intended for human or veterinary use, presented in their finished dosage form. Included here are materials used in the preparation and/or formulation of the finished dosage form.	Drug,Drugs,Pharmaceutical,Pharmaceutical Preparation,Pharmaceutical Product,Pharmaceutic Preparations,Pharmaceutical Products,Pharmaceuticals,Preparations, Pharmaceutical,Preparation, Pharmaceutical,Preparations, Pharmaceutic,Product, Pharmaceutical,Products, Pharmaceutical
D005374	Filtration	A process of separating particulate matter from a fluid, such as air or a liquid, by passing the fluid carrier through a medium that will not pass the particulates. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Filtrations
D001577	Benzophenones	Derivatives of benzophenone (with the structural formula phenyl-(C
D012995	Solubility	The ability of a substance to be dissolved, i.e. to form a solution with another substance. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)	Solubilities
D013473	Sunscreening Agents	Chemical or physical agents that protect the skin from sunburn and erythema by absorbing or blocking ultraviolet radiation.	Sunscreen,Sunscreens,Agents, Sunscreening