In vitro Spectroscopic studies on drug interaction of cefpodoxime proxetil and H2 receptor blockers.

One of the relatively advance 3rd generation cephalosporins, cefpodoxime proxetil, is being used all-around. Generally, these are used for the cure of infections allied to urinary and respiratory tract. These cephalosporins have showed a remarkable in vitro activity against many strains of bacteria which are resistant to other orally used active medicinal substances. It is the first oral 3rd generation cephalosporin to be used in the cure of skin infections. The practice of H2 receptor antagonists, concerning lots of treatments recommended in patients with different types of ulcers and allergic urticarial condition, is raising hazards of unwanted secondary outcomes and drug interactions. Learning of in-vitro interaction between cefpodoxime poxetil and H2 blockers (Ranitidine, Famotidine and Cimetidine) were examined applying UV/Visible spectrophotometry and Infrared spectrometry. In the existence of H2 receptor blockers, the cefpodoxime proxetil availability was found to be decreased in vitro only under specific conditions. Furthermore, complexes of Cefpodoxime proxetil-H2 receptor antagonists were manufactured approving the interaction of these drugs. Finally, the above mentioned spectrophotometric techniques were employed to examine the complexes formed (Cefpodoxime proxetil-cimetidine, cefpodoxime proxetil-famotidine and cefpodoxime proxetil-ranitidine).

Disposition of ceftizoxime in Staphylococcal mastitis in Indian crossbred cows.

Disposition of ceftizoxime was studied in Indian crossbred cows following a single IV dosing in field conditions. Six healthy lactating and six mastitic crossbred cows were assigned to two groups (Group 1 and Group 2). A single IV administration of ceftizoxime at the dose rate of 20mg/kg was administered to cows in both groups. Peak concentrations were recorded at 5min, decreasing sharply until 1h with plasma concentrations of 46.38±0.30µg/mL; concentrations were below detection limits at 24h. Ceftizoxime achieved peak concentrations at 96h and persisted up to 120h at a concentration of 36.71±0.96µg/mL in the milk of mastitic Indian crossbred cows. Staphylococcal colony count in acute mastitis was 52.33±4.98×105 colony forming units/mL milk and no growth was detected at 96h post-dosing, indicating that ceftizoxime following single IV administration at 20mg/kg may be effective to treat acute staphylococcal mastitis.

The urinary excretion of metformin, ceftizoxime and ofloxacin in high serum creatinine rats: Can creatinine predict renal tubular elimination?

The renal excretion of creatinine and most drugs are the net result of glomerular filtration and tubular secretion, and their tubular secretions are mediated by individual transporters. Thus, we hypothesized that the increase of serum creatinine (SCr) levels attributing to inhibiting tubular transporters but not glomerular filtration rate (GFR) could be used to evaluate the tubular excretion of drugs mediated by identical or partial overlap transporter with creatinine. In this work, we firstly developed the creatinine excretion inhibition model with normal GFR by competitively inhibiting tubular transporters, and investigated the renal excretion of metformin, ceftizoxime and ofloxacin in vivo and in vitro. The results showed that the 24-hour urinary excretion of metformin and ceftizoxime in model rats were decreased by 25% and 17% compared to that in control rats, respectively. The uptake amount and urinary excretion of metformin and ceftizoxime could be inhibited by creatinine in renal cortical slices and isolated kidney perfusion. However, the urinary excretion of ofloxacin was not affected by high SCr. These results showed that the inhibition of tubular creatinine transporters by high SCr resulted to the decrease of urinary excretion of metformin and ceftizoxime, but not ofloxacin, which implied that the increase of SCr could also be used to evaluate the tubular excretion of drugs mediated by identical or partial overlap transporter with creatinine in normal GFR rats.

Impact of different organic acids on solubility enhancement of cefpodxime proxetil immediate release tablet and its stability studies.

Cefpodoxime proxetil is a third generation cephalosporin antibiotic demonstrates pH dependent solubility and is highly soluble only in acidic pH. The purpose of this investigation was to design and develop immediate release tablets of cefpodoxime proxetil by direct compression method and determine the effect of different solid buffers (organic acids) such as fumaric acid (formulations F1-F4), maleic acid (formulations M1-M4) and citric acid (formulations C1-C4) by using cefpodoxime and acid in the ratios of 4:1, 2:1, 1:1 and 1:2 to achieve pH-independent release of the drug. Physical parameters and assay were found to be within the acceptable range as prescribed in USP 36 / NF 31. In vitro dissolution studies of each formulation were performed in distilled water, USP dissolution medium, HCl buffer solution of pH 1.2, phosphate buffer solutions of pH 4.5 and 6.8 to observe the drug release. The formulations F3, F4, M4 were selected for film coating on the basis of better drug release profile, to protect the drug from chemical degradation through hydrolysis. Film coated formulation F3, F4 and M4 showed a remarkable in vitro release of the drug (72.88±0.43 to 92.67±0.71%) within 30min of observation in all dissolution media and further evaluated by model independent and model dependent approaches. The drug release was found to be best fit to Weibull model as highest r2adjusted (0.924-0.998) and lowest AIC (18.416-54.710) values were obtained in all dissolution media. R Gui® applied for stability studies of F3 and F4 formulations, showing shelf lives of 28 & 27months at ambient and 33 months at accelerated temperatures. Formulation F4 was chosen as best formulation on the basis of physical properties, highest dissolution rate and stability studies.

Validated HPLC method for the pharmacokinetic study of oral extended-release cefpodoxime proxetil chitosan-alginate beads in rabbits.

The aim of this study is to develop a simple and applicable HPLC method for the detection of cefpodoxime acid (CFA) in rabbit plasma after oral administration of cefpodoxime proxetil (CFP) loaded chitosan-alginate (CH-ALG) beads formulation. CFP is a prodrug that is deesterified in vivo to its active metabolite CFA to exhibit antibiotic activity. Chromatographic separation of CFA and internal standard (IS) was achieved by a RP18(C18), Phenomenax®100, (250×4.6mm) with the mobile phase consisting of (0.02mol/l (20mM) ammonium acetate solution and acetonitrile (92:8, v/v, pH=4.6) at a flow rate of 1.0ml/min. The method was validated according to the requirements of US-FDA guidelines for bioanalytical method validation. The linear regression analysis for the calibration plots showed good linear relationship (R2=0.9905) in the working concentration range of 0.5-50µg/ml. The limits of detection and quantification (S/N=3) were 0.069 and 0.136µg/ml. Plasma CFA levels were successfully determined in rabbit with satisfactory precision and accuracy. The analyte was found to be stable after a number of stability studies. The proposed HPLC method was successfully applied to pharmacokinetic study in rabbits for CFP loaded CH-ALG beads and marketed immediate release (IR) tablets. All pharmacokinetic parameters were assessed.

Validation and Application of an LC-MS-MS Method for the Determination of Ceftizoxime in Human Serum and Urine.

Ceftizoxime sodium is a third-generation cephalosporin available for parenteral administration, which is mainly excreted through urine. A rapid and sensitive ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS-MS) method was developed and validated for the determination of ceftizoxime in human serum and urine. The samples were purified by protein precipitation and separated on an XTerra Phenyl column (4.6 × 50 mm, 5 µm). Electrospray ionization in the positive ion mode and multiple reaction monitoring were used to monitor the ion transitions at m/z 383.9/227.0. The results revealed that the method had excellent selectivity. The linear range covered from 2.50 to 10,000 ng/mL in serum and from 0.500 to 50.0 µg/mL in urine, respectively. Intra-batch and inter-batch precisions (in terms of relative standard deviation) were all <15% and the accuracies (in terms of relative error) were within the range of ± 15%. The lower limit of quantification, stability and extraction recovery were also validated and satisfied the criteria of validation. Finally, the method was successfully applied to a pharmacokinetic study of Chinese elderly healthy subjects after intravenous administration. The Cmax values in serum were 34,721.3 ± 5,697.3 ng/mL. Serum concentrations declined with t1/2 of 2.57 ± 0.22 h.

Using Monte Carlo simulation to determine optimal dosing regimen for cefetamet sodium for injection.

The objective of the study was to use Monte Carlo simulation to determine the optimal treatment dosing regimen of the cefetamet sodium for injection by analysing the pharmacokinetics (PK) parameters in healthy Chinese volunteers, and antibacterial activity in vitro was also examined. A three-cross Latin square single-dose PK study was designed. Twelve healthy volunteers were randomized to receive 500, 1000, and 2000 mg of cefetamet sodium for IV infusion over 30 minutes in three periods sequentially; and the washout time in between periods was 3 days. The drug concentrations in plasma were analysed by high-performance liquid chromatography, and the PK parameters were calculated using DAS2.0 PK software. The peak concentrations (Cmax) at 0.5 hours were 37.78±7.29, 76.18±12.81, and 149.32±29.94 mg/l, the areas under concentration-time curve (AUC0-t) were 69.75±14.44, 139.06±22.62, and 278.54±53.12 mg h/l, and the elimination half-life (t1/2) were 1.69±0.19, 1.69±0.27, and 1.81±0.23 hours for 500, 1000, and 2000 mg of cefetamet sodium for injection, respectively. The disposition of cefetamet was appear to fit a two-compartment model with linear kinetics. Antibacterial activity in vitro showed that most Gram-negative bacteria, including non-extended-spectrum beta-lactamases (ESBL)-producing Enterobacter, Haemophilus influenzae, Moraxella catarrhalis, and Neisseria gonorrhoeae, were sensitive to cefetamet. The result of Monte Carlo simulation showed that the probability of target attainment for bactericidal response (%fT>MIC≧50%) for susceptible bacteria was reached at all three dosing regimens of 500 mg, q6h, 1000 and 2000 mg, q8h and q6h. Considering the efficacy, safety, and pharmacoeconomy comprehensively, we recommended the dosing regimen of 500 mg, q6h for further clinical treatment based on the principle of minimum daily dosage.

Alendronate-coated long-circulating liposomes containing 99mtechnetium-ceftizoxime used to identify osteomyelitis.

Osteomyelitis is a progressive destruction of bones caused by microorganisms. Inadequate or absent treatment increases the risk of bone growth inhibition, fractures, and sepsis. Among the diagnostic techniques, functional images are the most sensitive in detecting osteomyelitis in its early stages. However, these techniques do not have adequate specificity. By contrast, radiolabeled antibiotics could improve selectivity, since they are specifically recognized by the bacteria. The incorporation of these radiopharmaceuticals in drug-delivery systems with high affinity for bones could improve the overall uptake. In this work, long-circulating and alendronate-coated liposomes containing (99m)technetium-radiolabeled ceftizoxime were prepared and their ability to identify infectious foci (osteomyelitis) in animal models was evaluated. The effect of the presence of PEGylated lipids and surface-attached alendronate was evaluated. The bone-targeted long-circulating liposomal (99m)technetium-ceftizoxime showed higher uptake in regions of septic inflammation than did the non-long-circulating and/or alendronate-non-coated liposomes, showing that both the presence of PEGylated lipids and alendronate coating are important to optimize the bone targeting. Scintigraphic images of septic or aseptic inflammation-bearing Wistar rats, as well as healthy rats, were acquired at different time intervals after the intravenous administration of these liposomes. The target-to-non-target ratio proved to be significantly higher in the osteomyelitis-bearing animals for all investigated time intervals. Biodistribution studies were also performed after the intravenous administration of the formulation in osteomyelitis-bearing animals. A significant amount of liposomes were taken up by the organs of the mononuclear phagocyte system (liver and spleen). Intense renal excretion was also observed during the entire experiment period. Moreover, the liposome uptake by the infectious focus was significantly high. These results show that long-circulating and alendronate-coated liposomes containing (99m)technetium-radiolabeled ceftizoxime have a tropism for infectious foci.

Pharmacokinetics and pharmacodynamics of oral and intravenous cefetamet in dog.

The pharmacokinetic (PK) and pharmacodynamic (PD) properties of intravenously (IV) administered cefetamet-Na and per os (PO) administered cefetamet pivoxil were investigated in eighteen healthy dogs at three different dose levels. The three doses for IV cefetamet-Na were 95, 190 and 380 mg, while those for oral cefetamet pivoxil were 125, 250 and 500 mg (both equivalent to 90, 180 and 360 mg of cefetamet). An efficacy predictor, measured as the ratios of the time that the concentration of the free drug is over the MIC90 (T > MIC90) and the dosing interval (f% T > MIC90) of IV and PO administration were calculated. The PK parameters' maximum concentration (C max), half-life (t 1/2) and area under the curve (AUC0-t ) after three IV doses were 42.85 ± 11.79 µg/mL, 1.66 ± 0.36 h and 80.10 ± 28.92 mg h/L (95 mg); 93.50 ± 30.51 µg/mL, 1.47 ± 0.13 h and 1.47 ± 0.13 mg h/L (190 mg); 185.74 ± 113.83 µg/mL, 1.60 ± 0.38 h and 263.20 ± 73.27 mg h/L (380 mg). After PO administration, the C max, t 1/2 and AUC0-t at three doses were 9.25 ± 1.02 µg/mL, 1.79 ± 0.50 h and 31.90 ± 4.76 mg h/L (125 mg); 9.75 ± 1.77 µg/mL, 1.93 ± 0.65 h and 42.69 ± 8.93 mg h/L (250 mg); 15.55 ± 6.65 µg/mL, 2.02 ± 0.54 h, and 68.72 ± 24.11 mg h/L (500 mg). The IV f% T > MIC90 was greater than PO f% T > MIC90 when MIC90 was within the range of 0.25-256 mg/L.

[Phase I clinical trial on the safety of injectable cefetamet sodium with a single dose in healthy volunteers].

OBJECTIVE: To investigate the safety and maximum tolerable dosage of injectable cefetamet sodium Sixty healthy volunteers were enrolled in this study. with a single infusion in Chinese healthy volunteers. METHODS: A double-blinded, randomized, placebo-controlled design was adopted. Eight dosages ranging from 100 mg to 5 000 mg were tested. The pharmacokinetics of the drug was analyzed using a Latin square three-cross self-controlled design, with 12 healthy volunteers receiving 500 mg, 1 000 mg and 2 000 mg of injectable cefetamet sodium in a randomized sequence. Blood and urine samples were collected and analyzed using high performance liquid chromatography with UV detection. The main pharmacokinetics parameters were calculated with DAS2.0 software. RESULTS: 59 healthy volunteers completed the tolerance tests. Clinical adverse reactions occurred in 22.73% of participants in the test group and 6.67% of participants in the placebo group; but the difference was not statistically significant. Common adverse events included infusion pain and dizziness. Rare adverse events such as palpitations, diarrhea and rash occurred in participants in the test group. All of the adverse reactions were mild. Abnormal laboratory test results occurred in 43.18% participants in the test group and 53.33% participants in the placebo group; again the difference was not statistically significant. Common abnormal laboratory test results included abnormal bowel flora, stool abnormalities, abnormal urine and elevated serum potassium. After a single infusion of 500 mg, 1 000 mg and 2 000 mg of injectable cefetamet sodium, peak concentration of the drug at 0.5 h reached (37.92 +/- 7.43), (74.90 +/- 10.67) and (148.54 +/- 31.63) mg/L, with areas under concentration-time curve of (72.08 +/- 14.98), (144.28 +/- 24.57) and (286.66 +/- 54.25) (mg x h)/L, respectively. Their elimination half-life was (2.03 +/- 0.38), (2.04 +/- 0.26), and (2.12 +/- 0.26) h, respectively. The disposition of cefetamet was presented as a two-compartment model with linear kinetics. The 24-hour urinary accumulation excretion was 76.6%-67.5%. CONCLUSION: The maximum single tolerated dose of injectable cefetamet sodium is 5 000 mg. The pharmacokinetics is a two-compartment model with linear kinetics within a dose range 500-2 000 mg.

Highly sensitive and selective high-performance liquid chromatography method for bioequivalence study of cefpodoxime proxetil in rabbit plasma via fluorescence labeling of its active metabolite.

Cefpodoxime proxetil (CFP), a broad-spectrum third-generation cephalosporin, has been used most widely in the treatment of respiratory and urinary tract infections. For bioequivalence study of CFP in rabbit plasma, it was necessary to develop a highly sensitive and selective high-performance liquid chromatographic (HPLC) method with fluorescence (FL) detection. The pre-column labeling of cefpodoxime acid (CFA) (active metabolite) with an efficient benzofurazan type fluorogenic reagent, 4-N,N-dimethyl aminosulfonyl-7-fluoro-2,1,3-benzoxadiazole (DBD-F) was carried out in the present study in 100mM borate buffer (pH=8.5) at 50°C for 15min. The obtained fluorescent products were separated on C18 column with an isocratic elution of the mobile phase, which consists of 10mM phosphate buffer (pH=3.5)/CH3CN (70:30, v/v). The fluorescent product (DBD-CFA) was detected fluorimetrically at 556nm with an excitation wavelength of 430nm. Cefotaxime sodium was used as internal standard. The method was validated according to the requirements of US-FDA guidelines. The correlation coefficient of 0.999 was obtained in the concentration ranges of 10-1000ngmL(-1). The limits of detection and quantification (S/N=3) were 3 and 10ngmL(-1), respectively. Plasma CFA levels were successfully determined in rabbit with satisfactory precision and accuracy. The proposed HPLC-FL method was successfully applied to study bioequivalence in rabbits for two formulations of different brands contained CFP (prodrug) in a randomized, two-way, single-dose, crossover study and all pharmacokinetic parameters for the two formulations were assessed.

A simply HPLC method for determination of cefpodoxime in Chinese volunteer and pharmacokinetic study.

A sensitive HPLC method was developed for the determination of cefpodoxime in human plasma. After protein precipitation with acetonitrile, sample was injected into the HPLC system for analysis. The chromatographic separation was carried out on a Diamonsil C18 column with a mobile phase consisting of acetonitrile-water. The mobile phase composed of water (containing 20 mmol/L monoammonium phosphate) and acetonitrile (90: 10, v/v). The detection wavelength was set at 254 nm. The standard curve for cefpodoxime was linear over the concentration range of 0.05-8 µg/mL with a lower limit of quantification of 0.05 µg/mL. The intra- and inter-day RSD values were lower than 10%, and the RE values were within±5%. For the pharmacokinetic analysis of plasma, the mean (SD) values obtained for the formulation were: Cmax, 4.21 (0.62) µg/mL; Tmax, 2.47 (0.61) h; t1/2, 2.38 (0.46) h; AUC0-24 h, 21.13 (3.39) µg/mL/h; and AUC0-∞, 23.34 (3.87) µg/mL/h; MRT, 2.21 (0.41) h, respectively.

AuNPs-poly-DAN modified pyrolytic graphite sensor for the determination of Cefpodoxime Proxetil in biological fluids.

A sensitive and selective electrochemical method for Cefpodoxime Proxetil (CP) determination has been developed by incorporating gold nanoparticles (AuNPs) onto the poly-1,5-diaminonapthalene layer (p-DAN) coated pyrolytic graphite. The modified sensor was characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The sensor exhibited an effective catalytic response towards oxidation of CP with excellent reproducibility and stability. The peak current of CP was found to be linear in the range of 0.1-12 µM and detection limit and sensitivity of 39 nM (S/N=3) and 4.621 µA µM(-1), respectively, were observed. The method was successfully applied for the determination of CP in pharmaceutical formulations and human urine samples. The common metabolites present in human urine such as uric acid, ascorbic acid, xanthine and hypoxanthine did not interfere in the determination. A comparison of the results obtained by using developed method with high performance liquid chromatography (HPLC) indicated a good agreement. The method is simple, sensitive, rapid and precise and is useful for the routine determination of CP in pharmaceutical dosages and biological samples.

Technetium-99m-labeled ceftizoxime loaded long-circulating and pH-sensitive liposomes used to identify osteomyelitis.

Osteomyelitis is an infectious disease located in the bone or bone marrow. Long-circulating and pH-sensitive liposomes containing a technetium-99m-labeled antibiotic, ceftizoxime, (SpHL-(99m)Tc-CF) were developed to identify osteomyelitis foci. Biodistribution studies and scintigraphic images of bone infection or non infection-bearing rats that had been treated with these liposomes were performed. A high accumulation in infectious foci and high values in the target-non target ratio could be observed. These results indicate the potential of SpHL-(99m)Tc-CF as a potential agent for the diagnosis of bone infections.

Comparison of cefpodoxime proxetil release and antimicrobial activity from tablet formulations: complexation with hydroxypropyl-ß-cyclodextrin in the presence of water soluble polymer.

This study aims to prove the complexation of cefpodoxime proxetil (CP) by hydroxypropyl-ß-cyclodextrin (HP-ß-CD) in the presence of sodium carboxymethyl cellulose (Na CMC), and makes a comparison of commercial tablets by dissolution and antimicrobial activity studies. The CP--HP-ß-CD complex was prepared by kneading method and characterized by SEM, FTIR and DSC. The solubility method was used to investigate the effect of HP-ß-CD and Na CMC on the solubility of CP. The complex tablets were prepared using direct compression method. Dissolution studies were performed with complex tablets and commercial tablets in pH 1.2, 4.5, 6.8 and 7.4 buffer solutions. It was observed that complexation occurred in all formulations, and HP-ß-CD is able to increase CP solubility and dissolution rate of CP was improved from complex tablets, when compared with commercial tablets. Furthermore, the antimicrobial activity studies revealed that the CP--HP-ß-CD complex and complex tablets were shown to have more effective antimicrobial activity than commercial tablets. It is evident from the results that complexation with HP-ß-CD in the presence of Na CMC is feasible way to prepare a more efficient tablet formulation with improved dissolution and antimicrobial activity.

Pharmacokinetics of cefpodoxime in plasma and subcutaneous fluid following oral administration of cefpodoxime proxetil in male beagle dogs.

Pharmacokinetics of cefpodoxime in plasma (total concentration) and subcutaneous fluid (free concentration using microdialysis) was investigated in dogs following single oral administration of prodrug cefpodoxime proxetil (equivalent to 5 and 10 mg/kg of cefpodoxime). In a cross over study design, six dogs per dose were utilized after a 1 week washout period. Plasma, microdialysate, and urine samples were collected upto 24 h and analyzed using high performance liquid chromatography. The average maximum concentration (C(max) ) of cefpodoxime in plasma was 13.66 (±6.30) and 27.14 (±4.56) µg/mL with elimination half-life (t(1/2) ) of 3.01 (±0.49) and 4.72 (±1.46) h following 5 and 10 mg/kg dose, respectively. The respective average area under the curve (AUC(0-∞) ) was 82.94 (±30.17) and 107.71 (±30.79) µg·h/mL. Cefpodoxime was readily distributed to skin and average free C(max) in subcutaneous fluid was 1.70 (±0.55) and 3.06 (±0.93) µg/mL at the two doses. Urinary excretion (unchanged cefpodoxime) was the major elimination route. Comparison of subcutaneous fluid concentrations using pharmacokinetic/pharmacodynamic indices of fT(>MIC) indicated that at 10 mg/kg dose; cefpodoxime would yield good therapeutic outcome in skin infections for bacteria with MIC(50) upto 0.5 µg/mL while higher doses (or more frequent dosing) may be needed for bacteria with higher MICs. High urine concentrations suggested cefpodoxime use for urinary infections in dogs.

Quantitative determination of cefetamet in human plasma by liquid chromatography-mass spectrometry.

Cefetamet is a potent antibiotic to treat respiratory and urinary tract infections. To improve oral bioavailability, it is administered as a prodrug, cefetamet pivoxyl hydrolyzed by esterase following absorption. A quantification method using a mass spectrometry was developed for the determination of cefetamet in human plasma. After a protein precipitation with acetonitrile, the analytes were chromatographed on a reversed-phase C18 column and detected by a tandem mass spectrometer with electrospray ionization. The accuracy and precision of the assay were in accordance with FDA regulations for the validation of bioanalytical methods. This method was used to measure the concentrations of the cefetamet in plasma after a single oral administration of 500 mg cefetamet pivoxyl.

Pharmacokinetics of cefpodoxime proxetil with special reference to biochemical parameters, tissue residue, and spermatozoa motility in rats.

BACKGROUND: Cefpodoxime is a semisynthetic third generation cephalosporin analogue with a relatively broader spectrum of antimicrobial activity against gram negative and gram positive organisms. This is attributed to their somewhat increased resistance to degradation by the betalactamase. Cefpodoxime shows good activity against Klebsiella pneumonia, many members of enterobactericeae and almost all strains of Escherichia coli. It is extensively used in human beings against infections caused by susceptible organisms for a prolonged period and even without its judicious indication. Though various researchers have worked on the pharmacokinetic aspects of the drug, its effects on biochemical parameters and spermatozoa activity are scarcely available in literature. AIM: To determine the oral kinetic ( blood and tissue) after single therapeutic dose of cefpodoxime proxetil (20mg/kg oral bid 7 days) in rats of either sex on tissue half life and certain biochemical parameters such as glucose, hemoglobin, protein, ALT, AST and other parameters like tissue residue, sperm count and spermatozoa motility in male rats. MATERIALS AND METHODS: For kinetic studies,24 Wister rats of either sex, 3 months of age, (180-210 gm) were used.(Group I-IV; n=6) Blood samples collected from each animal of Group IV through heart puncture at 0 hour to serve as predrug control. All the group (I-IV) received cefpodoxime proxetil 20 mg/kg once orally as a single dose. At the end of 1,4,12 and 24 hour post oral administration, GroupI,II,III and IVwere utilized for kinetic studies. Blood samples were collected from each animal and vital organs viz brain, lung, liver, spleen, kidney and heart were dissected out for drug analysis and determination of weight. For biochemical parameters, tissue residue and spermatozoa motility, twelve male rats were randomly divided into Groups A and B (n=6) Group B received cefpodoxime (20mg/kg orally bid 7 days) while Group A served as control. Biochemical parameters [Blood glucose, protein, Aspartate transaminase(AST), Alanine transaminase(ALT)and hemoglobin] were measured at 0 and 7 th day while sperm count (total,live and dead)and mean organ weight (study and control group) and tissue residue of drug were evaluated at the end of treatment. Absorption of cefpodoxime was observed at 2 hour and reached a maximum at 4 hour and persisted in blood till 24 hour. Elimination half life in lung was highest followed by heart, liver, kidney and spleen while t½ k in plasma was very low suggesting more affinity of cefpodoxime for tissues than blood. RESULTS AND CONCLUSION: Blood glucose, protein, AST and ALT activities were not significantly altered but the hemoglobin level and total and live sperm count decreased significantly in the study group compared to the control group. Residual level of cefpodoxime was highest in liver followed by kidney and other study organs. Therefore, the drug should be used in human beings judiciously and further study on human subjects is warranted.

Pharmacokinetics, protein binding, and tissue distribution of orally administered cefpodoxime proxetil and cephalexin in dogs.

OBJECTIVE: To determine the effect of protein binding on the pharmacokinetics and distribution from plasma to interstitial fluid (ISF) of cephalexin and cefpodoxime proxetil in dogs. ANIMALS: 6 healthy dogs. PROCEDURES: In a crossover study design, 25 mg of cephalexin/kg or 9.6 mg of cefpodoxime/kg was administered orally. Blood samples were collected before (time 0) and 0.33, 0.66, 1, 2, 3, 4, 6, 8, 10, 12, 16, and 24 hours after treatment. An ultrafiltration device was used in vivo to collect ISF at 0, 2, 4, 6, 8, 10, 12, 16, and 24 hours. Plasma and ISF concentrations were analyzed with high-pressure liquid chromatography. Plasma protein binding was measured by use of a microcentrifugation technique. RESULTS: Mean plasma protein binding for cefpodoxime and cephalexin was 82.6% and 20.8%, respectively. Mean ± SD values for cephalexin in plasma were determined for peak plasma concentration (Cmax, 31.5±11.5 µg/mL), area under the time-concentration curve (AUC, 155.6±29.5 µg•h/mL), and terminal half-life (T½, 4.7±1.2 hours); corresponding values in ISF were 16.3±5.8 µg/mL, 878±21.0 µg•h/mL, and 3.2±0.6 hours, respectively. Mean±SD values for cefpodoxime in plasma were 33.0±6.9 µg/mL (Cmax), 282.8±44.0 µg•h/mL (AUC), and 5.7±0.9 hours (T1/2); corresponding values in ISF were 4.3±2.0 µg/mL, 575±174 µg•h/mL, and 10.4±3.3 hours, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Tissue concentration of protein-unbound cefpodoxime was similar to that of the protein-unbound plasma concentration. Cefpodoxime remained in tissues longer than did cephalexin.

Enhancement of bioavailability of cefpodoxime proxetil using different polymeric microparticles.

Poorly water-soluble drugs such as cefpodoxime proxetil (400 µg/ml) offer a challenging problem in drug formulation as poor solubility is generally associated with poor dissolution characteristics and thus poor oral bioavailability. According to these characteristics, preparation of cefpodoxime proxetil microparticle has been achieved using high-speed homogenization. Polymers (methylcellulose, sodium alginate, and chitosan) were precipitated on the surface of cefpodoxime proxetil using sodium citrate and calcium chloride as salting-out agents. The pure drug and the prepared microparticles with different concentrations of polymer (0.05-1.0%) were characterized in terms of solubility, drug content, particle size, thermal behavior (differential scanning calorimeter), surface morphology (scanning electron microscopy), in vitro drug release, and stability studies. The in vivo performance was assessed by pharmacokinetic study. The dissolution studies demonstrate a marked increase in the dissolution rate in comparison with pure drug. The considerable improvement in the dissolution rate of cefpodoxime proxetil from optimized microparticle was attributed to the wetting effect of polymers, altered surface morphology, and micronization of drug particles. The optimized microparticles exhibited excellent stability on storage at accelerated condition. The in vivo studies revealed that the optimized formulations provided improved pharmacokinetic parameter in rats as compared with pure drug. The particle size of drug was drastically reduced during formulation process of microparticles.