PubMed · 406004
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S Selwyn, M Bakhtiar. 1977-07-09. Penicillin-resistant gonococci.. https://doi.org/10.1136/bmj.2.6079.118-a
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Gellan gum beads containing cephalexin were prepared by extruding the dispersion of cephalexin and gellan gum into a solution containing a mixture of calcium and zinc ions (counterions). Beads were prepared by changing experimental variables such as pH of the counterion solution and amount of cephalexin loading in order to optimize process variables on the final % drug entrapment efficiency, release rates, size, and morphology of the beads. Absence of chemical interactions between drug, anionic polymer, and counterions after production of beads was confirmed by Fourier transform infrared spectroscopy. Differential scanning calorimetry was used to understand the crystalline nature of the drug after its successful entrapment. These data indicated the amorphous dispersion of cephalexin in the polymer matrix. Beads were spherical in shape, with the average bead size ranging from 925 to 1183 microm as measured by the laser light scattering technique. Cephalexin entrapment of up to 69.24% was achieved. In vitro release studies were performed in 0.1 N HCl or pH 7.4 phosphate buffer and the release of cephalexin was achieved up to 6 h. Dynamic swelling studies were performed in 0.1 N HCl or pH 7.4 phosphate buffer. Diffusion coefficients were calculated for spherical geometry. The release data have been fitted to an empirical relation to estimate the transport parameters. Mathematical modeling studies were performed for spherical geometry by solving Fick's equation to compute concentration profiles. These results were correlated with the release profiles.
A highly selective molecularly imprinted solid phase extraction (MISPE)-pulsed elution (PE) method coupled with electrospray mass spectrometry (MS) was developed for the rapid screening and determination of cephalexin in alpha-aminocephalosporin antibiotics. This method involved the solid phase extraction of cephalexin using a molecularly imprinted polymer micro-column, and pulsed elution with 1% trifluoroacetic acid in methanol, which contains sulindac as an internal standard for enhanced precision in MS detection. An LC/MS spectrometer was operated in the positive electrospray mode, and the selected-ion-recording (SIR) function was employed to detect the molecular ions of cephalexin, cefradine, cefadroxil and sulindac at m/z 348, 350, 363 and 357. Linearity was achieved in the cephalexin concentration range from 0.3 to 25microg/ml (or 5-500ng) (R(2) = 0.998). The detection limit was estimated at 0.04microg/ml (or 0.8ng) of cephalexin. Advantages of the newly developed MISPE-PE-MS, over the previously reported MISPE-DPE-FPE-UV, were evidenced in terms of detection limit, analysis time, solvent consumption, and simplicity of method development.
The object of this study was to develop hydroxypropyl methylcellulose (HPMC) based cephalexin extended release tablet, which can release the drug for six hours in predetermined rate. Twenty-one batches of cephalexin tablets were prepared by changing various physical and chemical parameters, in order to get required theoretical release profile. The influences of HPMC, microcrystalline cellulose powder (MCCP), granulation technique, wetting agent and tablet hardness on cephalexin release from HPMC based extended release tablets were studied. The formulated tablets were also characterized by physical and chemical parameters. The dissolution results showed that a higher amount of HPMC in tablet composition resulted in reduced drug release. Addition of MCCP resulted in faster drug release. Tablets prepared by dry granulation was released the drug slowly than the same prepared with a wet granulation technique. Addition of wetting agent in the tablets prepared with dry granulation technique showed slower release. An increase in tablet hardness resulted in faster drug release. Tablets prepared with a wet granulation technique and having a composition of 9.3% w/w HPMC with a hardness of 10-12 kg/cm(2) gave predicted release for 6 h. The in vitro release data was well fit in to Higuchi and Korsmeyer-Peppas model. Physical and chemical parameters of all formulated tablets were within acceptable limits. One batch among formulated twenty-one batches was successful and showed required theoretical release. The effect of storage on in vitro release and physicochemical parameters of successful batch was studied and was found to be in acceptable limits.