Studies On The Preparation Of The Powdery Injection Of The Rifapentine

Rifapentine is a new type of semisynthetic antibiotic belonging to the rifamycin group. It has an antibacterial specitrum similar to rifampicin, but its antiuberculosis power is 2-10 fold stronger than that of rifampicin, its toxic reaction is lower and its half- time is longer. It has been used for its extensive bacteriostatic activity to Staphylococcus aureus, Gram-positive bacteria, Gram-negative bacteria. Above all, tubercle bacillus, leprosy.Until now, capsule is only available product of Rifapentine. To improve the bioavailability and increase the preparation, we begin the research on solubility and choose ethanol, 1,2-propanediol, surface active agent, 0.9%NS to use as solvent. Orthogonal design experiment was employed to optimize the high concentration formulation. With the best formulation selected, a method of determination of Rifapentine in the injection by high performance liquid chromatograph (HPLC) was developed. The method utilized a C₁₈ column, the mobile phase consisted of methanol: acetonitrile: 0.2mol/mLphosphate buffer solution =150:150: 150 (pH=7.5) was pumped at a flow rate of 1.0ml/mL, the column temperature was 25℃, the injection volume was 5μL, the detector was fixed at an wavelength of 336nm. The experiment gives a good linear (r=0.9995) over the concentration from 20 to 200 μg · mL^-1, RSD of precision of RPT is 1.05%, recovery of RFT is 99.92%, RSD is 1.35%. The method is simple, rapid and accurate.We carried out the safety test : haemolyticus test, venous irritation test, muscle irritation test, hypersensitivity test. Safety of Rifapentine powder injection is similar to standard. Acute toxicity in rats by intravenous exhibited that LD₅₀ is 389.0mg/kg and limit of reliability is from 503.5 to 300.6 mg/kg. Acute toxicity in rats by celica is 393.5mg/kg, limit of reliability is from 437.5 to 346.0mg/kg. Cumulative toxicity coefficient is low.