Influence of light and temperature on the stability of procaine hydrochloride injection.

AIM: To study the influence of light and heat on the stability of procaine hydrochloride injection. METHODS: Accelerated tests upon exposure to light at high temperatures were employed. RESULTS: In experiments with either isothermal heating or exposure to light at high temperatures, the drug degradation rate obeys first-order kinetics. The total rate constant, ktotal, caused by both light and heat can be divided into two parts: ktotal = kdark + klight, where kdark and klight are the rate constants caused by heat and light, respectively. The klight can be expressed as klight = Alight x E x exp(-Ea,light/RT). Where E is the illuminance of light, Alight is an experimental constant related to light sources, and Ea,light is an experimental constant. CONCLUSION: Because the form of klight is similar to the Arrhenius equation, it is suggested that Ea,light might be the observed activation energy of the rate-determining step of the subsequent processes of the photochemical reaction. This viewpoint is supported by the fact that the Ea,light is independent of light sources.

The ophthalmic rod: a new ophthalmic drug delivery system I.

The ophthalmic rod (OR) is a new drug delivery system, intended as an alternative to conventional therapy in ophthalmology. The rod is made of a nontoxic plastic. It is dipped into a drug solution which after drying forms a thin homogeneous coating. The OR is then packed and sterilized by gamma radiation. The effects of radiation on the contents of the drugs were studied using IR, UV, and thin-layer chromatography (TLC). Sterility, dose variation, and simulated drug delivery in vitro were tested. Pure drugs were used; no preservatives were included. To deliver the drug, the tip of the rod is introduced into the conjunctival sac and rubbed against the palpebral conjunctiva of the lower lid. ORs with tropicamide, oxybuprocaine HCl, pilocarpine HCl, and fluorescein sodium were used. The behavior of the drugs administered by this system was compared with eyedrops. Results of trials with three drugs, i.e., tropicamide, oxybuprocaine HCl, and fluorescein sodium on ORs applied to the eyes of humans and those of the rabbit are discussed.

Effect of 60Co-irradiation on penicillin G procaine in veterinary mastitis products.

The effect of 60Co-irradiation on penicillin G procaine in a peanut oil-based veterinary mastitis product was examined by reversed-phase high-performance liquid chromatography (HPLC). The HPLC method is capable of separating and quantifying procaine, penicillin G, and various degradation compounds. Penicillin G recovery from a placebo formulation was 100.4% with a relative standard deviation of less than 1%. When irradiated at 4.0 Mrads, the penicillin G in two product lots decreased slightly (approximately 1-2%) with a corresponding increase in two compounds inherently present in bulk penicillin G powder. These compounds may be formed in abundance by treating penicillin G in an acidic solution. From the mass spectrometric analysis and the relative retention data with authentic compounds, these compounds were identified as benzylpenilloaldehyde and benzylpenaldic acid. Values obtained by the HPLC method on the product irradiated and stored at various temperatures correlated well with those of the microbiological assay. No significant decrease in the procaine was detected even after 4.0-Mrad irradiation. The HPLC method is applicable for analysis of other beta-lactam antibiotics.