Compatibility of enalaprilat with dobutamine, dopamine, heparin, nitroglycerin, potassium chloride and nitroprusside.

The physical and chemical compatibility of enalaprilat in admixtures of dobutamine, dopamine, heparin, nitroglycerin, potassium chloride, or sodium nitroprusside, in 5% dextrose, were studied at room temperature over a 24-h period. Enalaprilat was found to be physically compatible and chemically stable in all admixture solutions tested.

Comparative bioavailability characteristics of commercial quinidine polygalacturonate and sulfate tablets.

This study compared the relative bioavailability characteristics of quinidine polygalacturonate (QP) and quinidine sulfate (QS) after oral administration of commercial tablets and a liquid form prepared from crushed tablets in 13 healthy adult male volunteers. Each subject received the following four single-dose treatments in a randomized, crossover manner with a one-week washout period between treatments: 400 mg QS liquid, two 200-mg QS tablets, 550 mg QP liquid, and two 275-mg QP tablets. All four treatments were equivalent in terms of the dose of quinidine base. Multiple serum samples and two 24-hour urine specimens were collected over 24 and 48 hours, respectively, and assayed for quinidine with a specific HPLC assay method. For the absorption and disposition parameters measured (maximum serum concentration, time to reach maximum concentration, area under the concentration-time curve [0-48 hours], absorption and elimination rate constants, absorption and elimination half-lives, apparent total body clearance, apparent volume of distribution, and dose fraction excreted in the urine) no significant differences were observed for any of the parameters among the four treatments (p greater than 0.05). The results of the present investigation demonstrated that QP and QS produced identical serum quinidine concentration-time curves when given in the form of a tablet or liquid. The clinical implications of these observations with respect to the dosing of QP are discussed.

Stability of esmolol hydrochloride in the presence of aminophylline, bretylium tosylate, heparin sodium, and procainamide hydrochloride.

The visual and chemical compatibility of esmolol hydrochloride mixed with aminophylline, heparin sodium, bretylium tosylate, or procainamide hydrochloride in 5% dextrose injection was studied. Esmolol hydrochloride 600 mg was injected into polyvinyl chloride bags containing 100 mL of 5% dextrose injection with aminophylline 100 mg, heparin sodium 5000 units, bretylium tosylate 100 mg, or procainamide hydrochloride 400 mg. All admixtures were prepared in triplicate and stored at room temperature under fluorescent light. Esmolol concentrations were measured with high-performance liquid chromatography at 0, 2, 4, 8, and 24 hours. Samples were also examined for precipitate formation and pH and color changes by using visual, microscopic, and spectrophotometric methods. No detectable changes in color or pH and no particulate formation were observed in any of the sample bags. Esmolol concentrations varied by less than 5% throughout the 24-hour study period. Esmolol hydrochloride was visually compatible and chemically stable for at least 24 hours when mixed with aminophylline, heparin sodium, bretylium tosylate, or procainamide hydrochloride in polyvinyl chloride bags containing 5% dextrose injection.

Effect of antacid on the bioavailabiity of lithium carbonate.

The effect of an antacid on the bioavailability of lithium carbonate was determined in six healthy men in a crossover study. The volunteers were given single 300-mg doses of lithium carbonate alone and with 30 ml of an antacid containing aluminum and magnesium hydroxides with simethicone. Blood samples were collected at various times for 0-24 hours after each dose. The plasma samples were analyzed for lithium using a spectrophotometer, and bioavailability variables were calculated from plasma lithium concentration-time curves. There were no significant differences in peak plasma lithium concentration, time to peak concentration, area under the concentration-time curve from 0 to 24 hours, first-order absorption rate constant, and first-order elimination rate constant between the two treatments. Concurrent administration of antacids and lithium carbonate should not affect lithium blood concentrations.

Effect of caffeine on the oral absorption and disposition of quinidine.

The effect of caffeine on the oral absorption and disposition of quinidine was assessed in nine healthy men. Single 300-mg doses of quinidine sulfate were given by mouth in the absence and presence of caffeine in a crossover study. In the caffeine-treatment phase, 1 g of caffeine was given per day in divided doses for one week before the administration of a second 300-mg quinidine sulfate dose. Blood samples were collected at various times for 24 hours after drug administration, and the sera were assayed for quinidine. Urine specimens were also analyzed for quinidine. No differences were found in the quinidine absorption and disposition constants between the control and caffeine-treated phases, using a nonlinear, least-squares regression analysis of the serum quinidine concentration-time curves and standard blood and urine bioavailability test methods. The hypothesis proposed by previous investigators that quinidine disposition may be altered by caffeine-inducible hepatic microsomal enzymes was not supported by these data. Caffeine treatment at a daily dose of 1 g per day for one week had no apparent effect on the absorption or disposition of quinidine after a single 300-mg oral dose of quinidine sulfate in healthy men.

Ceforanide vs. cephalothin concentrations in total joint arthroplasty.

Total joint arthroplasty is a common orthopedic procedure and requires prophylactic antibiotic coverage to prevent infections in the operated joint. The antibiotics routinely used for prophylaxis are the cephalosporins. This study compared bone, synovial fluid, and plasma concentrations of ceforanide with cephalothin concentrations in 30 patients undergoing elective total hip or total knee arthroplasty. Ceforanide provided significantly higher plasma concentrations for 61-110 minutes postdose than did cephalothin (p less than 0.025 and p less than 0.005). No difference was noted between the two antibiotics for the bone concentrations in the total hip arthroplasty group; however, cephalothin concentrated to a greater degree in the bone of patients undergoing total knee arthroplasty (p less than 0.05). Cephalothin achieved higher concentrations in the synovial fluid than did ceforanide (p less than 0.05). Both antibiotics were well tolerated and no postoperative infections were noted in either group.