Kr Stewart

STABILITY OF CEFUROXIME SODIUM IN SOME AQUEOUS BUFFERED SOLUTIONS AND INTRAVENOUS ADMIXTURES

Cefuroxime sodium (Zinacef®) is a new semisynthetic, broad spectrum cephalosporin antibiotic for parenteral administration which is stable to most of the β‐lactamases.

NOTE:CHEMICAL STABILITIES OF LIGNOCAINE HYDROCHLORIDE AND PHENYLEPHRINE HYDROCHLORIDE IN AQUEOUS SOLUTION

The chemical stabilities of lignocaine hydrochloride (lidocaine hydrochloride) and phenylephrine hydrochloride in a combination aqueous solution have been determined using stability‐indicating high‐performance liquid chromatographic methods. The drugs did not interact and were stable for at least 66 days at room temperature. The pH value changed from 6.0 to 5.8 after 66 days but was still within the optimum pH range for the stabilities of lignocaine and phenylephrine.

Stability of cefsulodin in aqueous buffered solutions and some intravenous admixtures.

The stability of cefsulodin in aqueous solutions of various pH values, buffer concentrations, ionic strengths and intravenous admixtures were studied using a stability‐indicating high‐pressure liquid chromatography method. The pH range of optimum stability was determined to be 3·2–5·7. Cefsulodin was more stable on the acidic and less on the alkaline side as compared with most of the other cephalosporins such as cefoxitin (pH range of optimum stability ˜ 4–7). In 5% dextrose and 0·9% sodium chloride injection, cefsulodin was stable (at least 90% potent) for about 1, 17 and at least 60 days at 24d̀, 5d̀ and ‐10d̀C, respectively.

CHEMICAL STABILITY OF THIOPENTAL SODIUM INJECTION IN DISPOSABLE PLASTIC SYRINGES

The chemical stability of thiopental sodium injection (2.5%) when stored at 25° and 5° in disposable plastic syringes of two manufacturers (Monoject and Becton Dickenson and Co.) has been studied using the USP‐NF method. The injection appeared to be stable for five days at 25° and 45 days at 5° with a loss in potency of less than 7%. The thiopental sodium did not adsorb on the syringes. The pH values and the physical appearance did not change. An additional peak was obtained in the chromatogram from both the freshly prepared and the assay solution probably due to an impurity in the powder.

STABILITY OF HYDRALAZINE HYDROCHLORIDE IN AQUEOUS VEHICLES

The stability of hydralazine hydrochloride in aqueous vehicles which contain either dextrose, fructose, lactose, maltose, mannitol, sorbitol or sucrose has been studied using a stability‐indicating high‐performance liquid chromatographic method. Dextrose, fructose, lactose and maltose had adverse effects on the stability of hydralazine. In mannitol (better than sorbitol) and sorbitol, hydralazine was stable for about 21 days (loss in potency of less than 10%) and sucrose had an adverse effect only after its hydrolysis to fructose and dextrose. The optimum pH range of stability in dextrose was approximately between 3.2 and 4.4. The first‐order rate of decomposition increased with an increase in the concentration of dextrose but not with an increase in the concentration of hydralazine. In the absence of other excipients the phosphate and citrate buffers did not adversely affect the stability of hydralazine hydrochloride.

Stability of metronidazole and ten antibiotics when mixed with magnesium sulphate solutions.

The chemical stabilities of metronidazole (in water) and ten antibiotics (ampicillin, carbenicillin, cefamandole, cefazolin, cefoxitin, moxalactam, nafcillin, penicillin G, piperacillin, and ticarcillin) in 5% dextrose injection (except ampicillin which was in 0.9% sodium chloride) with magnesium sulphate were studied at 25°C. The clarity of the solutions did not change in 20 h. The pH values of metronidazole, nafcillin and penicillin G solutions containing magnesium sulphate were lower (at 0 and 20 h) by up to 1.2 units as compared with solutions without magnesium sulphate. The decomposition of nafcillin and penicillin G solutions was hastened significantly by magnesium sulphate due to effect on the pH values of the solutions.

CHEMICAL STABILITIES OF CEFAMANDOLE NAFATE AND METRONIDAZOLE WHEN MIXED TOGETHER FOR INTRAVENOUS INFUSION

The chemical stabilities of cefamandole nafate and metronidazole, when mixed together for intravenous infusion, have been studied using a stability‐indicating, high‐performance liquid chromatographic method of assay. Cefamandole nafate was stable for 5 days at 25°C and at least 14 days at 5°C. The addition of metronidazole did not affect the stability of cefamandole nafate. In a 2% solution of cefamandole in metronidazole injection (0.5%), metronidazole lost about 9.1% of potency in less than 2h at 25°C and in less than 6 h at 5°C. The per cent loss was directly related to the initial concentration of cefamandole nafate. Change in the concentration of metronidazole did not affect the per cent of metronidazole lost.