Studies on the Crystal Forms of Selected Fluoroquinolones

Abstract

Prulifloxacin and Gemifloxacin are fourth generation Fluoroquinolones; they are broad-spectrum antibiotics which are active against both gram positive and gram-negative bacteria. They are mainly prescribed for the bacterial infections of complicated lower urinary tract infection, acute respiratory tract infection, simple cystitis, skin and soft tissue infection, E.N.T infection, bone and joint infection in children and adults and also community acquired pneumonia. The existence of various solid-state forms of active ingredients can drastically alter the physico-chemical properties of a pharmaceutical product. This may affect its effectiveness, stability, bioavailability, therapeutic efficacy and suitability of a particular formulation. Therefore, the development of suitable solid form is critical for the success of drug product. Solids may be prepared in a particular crystal form through various crystallization techniques. These solid forms are differing from each other with respect to many properties such as internal crystal lattice, crystal shape, solubility, dissolution rate, flow properties and compaction behavior. The observation from the dissolution rate profiles and solubility measurement of all the four crystalline forms explained that the G-I crystal had highest solubility and percentage drug release. Maximum solubility was found in G-I. Rest of the other crystal forms offered more or less the same solubility. The drug content observed for all the developed crystals between 97% - 98% indicated good stability after storage at accelerated stability condition. Finally it can be concluded that the four different polymorphs of gemifloxacin mesylate were identified based on SEM, FT-IR, DSC and PXRD studies. The mean peak plasma concentration of G-I form (Cmax 3.06 and#956;g/ml) was more than the pure form which was indicative of the rate and extent of oral absorption. The absorption rate of G-I forms showed greatly up at 1 hr with highest AUCand#8734; value (11.88and#956;g/ml) which expressed the higher bioavailability than pure form.