Simultaneous determination of cinnamaldehyde, eugenol and piperine by HPTLC densitometric method.

An HPTLC densitometric method for the simultaneous determination of cinnamaldehyde and eugenol as well as trace amounts of piperine in pepper-contaminated cinnamon was developed. The applicability of the method was tested with cinnamon bark powder adulterated with pepper powder, cinnamon oil, clove powder, clove oil and a commercial preparation containing cinnamaldehyde and eugenol. The method was validated for specificity, precision, accuracy and robustness. The method was found to be precise for different concentrations of cinnamaldehyde, eugenol and piperine. The accuracy of the method was checked by conducting a recovery study at three different levels. The linearity was found to be in the ranges 52.54-735.56, 533.2-8531.2 and 50-300 ng/spot, respectively, with correlation coefficients of 0.9985 +/- 0.04, 0.9982 +/- 0.06 and 0.9937 +/- 0.11 for cinnamaldehyde, eugenol and piperine.

Effect of rifampicin pretreatment on the transport across rat intestine and oral pharmacokinetics of ornidazole in healthy human volunteers.

Increased exsorption of ornidazole was observed from different parts of the small intestine of the rat after pretreated with rifampicin and sodium butyrate by the everted sac method. Based on the in vitro studies the effect of rifampicin pretreatment on the pharmacokinetics of ornidazole was investigated in eight healthy male volunteers. After an overnight fast, 500 mg ornidazole was administered to the volunteers, either alone or after 6 days pretreatment with a once daily dose of 600 mg rifampicin. Serum concentrations of ornidazole were estimated by reverse phase HPLC. Pharmacokinetic parameters were determined based on non-compartmental model analysis using the computer program Win Nonlin 1.1. Rifampicin preteatment resulted in a significant decrease in AUC, C(max) and t1/2, by 21.16%, 20.43% and 18.11%, respectively. Clearance was increased significantly by 32.14%. This may be due to increased induction of cytochrome P450 enzymes and/or increased expression of P-glycoprotein. This interaction may have clinical significance when ornidazole is co-administered with rifampicin in chronic treatment conditions, such as tuberculosis, leprosy and other infections of joints, bones, etc.

Effect of system variables involved in packed column supercritical fluid chromatography of stavudine taken as model analyte using response surface methodology along with study of thermodynamic parameters.

A multifactor optimization technique is successfully applied to study the effect of simultaneously varying the system variables on feasibility of stavudine analysis by packed column supercritical fluid chromatography (PC-SFC). The effect of simultaneously varying the pressure, temperature and modifier concentration was studied to optimize the method in order to obtain excellent chromatographic figures of merit. The method is based on isocratic elution using methanol-modified supercritical carbon dioxide as the mobile phase at the flow rate of 3.0 ml/min through a JASCO Finepak SIL-5, ODS [C(18) (5 microm, 25 cm x 4.6 mm, i.d.)] column support using photodiode array detection. The optimal conditions were determined with the aid of the response surface methodology using 3(3) factorial designs. From the response surface graphs optimum regions were selected to be +1, -1, and +1 for temperature (60 degrees C), pressure (20 MPa) and percent modifier concentration (17.81%, v/v), respectively. Linearity dynamic range was found to be in the range of 2.0-150.0 microg/ml with significantly high value of correlation coefficient. The method was validated for precision, robustness and recovery to assess the viability of the established method. The chromatographic limit of detection and quantitation were 0.80 and 1.50 microg/ml respectively. The method has been successfully used to analyze commercial dosage form to assess the chromatographic performance of SFC system which was found to be 99.91%+/-1.62. The present work briefs the thermodynamic applications of PC-SFC with an emphasis on the results of stavudine. The foremost of such applications is the determination of solute diffusion coefficient in supercritical mobile phase by Taylor-Aris peak broadening technique.

Effect of system variables involved in packed column SFC of nevirapine as model analyte using response surface methodology: application to retention thermodynamics, solute transfer kinetic study and binary diffusion coefficient determination.

A multifactor optimization technique is successfully applied to study the effect of simultaneously varying the system variables on feasibility of nevirapine analysis by packed column supercritical fluid chromatography (PC-SFC). The optimal conditions were determined with the aid of the response surface methodology using 3(3) factorial designs. The method is based on methanol-modified carbon dioxide as the mobile phase at flow rate of 3.0 ml/min with elution through a JASCO Finepak SIL-5, [C18 (5-micron, 25 cm x 4.6 mm, i.d.)] column using photodiode array detection. The method has been successfully used to analyze commercial solid dosage form to assess the chromatographic performance of SFC system. The present work briefs the thermodynamic applications of PC-SFC with an emphasis on the results of nevirapine. The foremost of such applications is the determination of solute diffusion coefficient in supercritical mobile phase by Taylor-Aris peak broadening technique.

The ICH guidance in practice: stress degradation studies on indinavir sulphate and development of a validated specific stability-indicating HPTLC assay method.

A sensitive, selective, precise and stability-indicating high-performance thin layer chromatography (HPTLC) method for analysis of indinavir sulphate both as a bulk drug and in formulations was developed and validated. The method employed TLC aluminium plates precoated with silica gel 60F-254 as the stationary phase. The solvent system consisted of carbon tetrachloride/chloroform/methanol/10% v/v ammonia (4:4.5:1.5:0.05, v/v/v/v). Densitometric analysis of indinavir sulphate was carried out in the absorbance mode at 260 nm. This system was found to give compact spots for indinavir sulphate (Rf value of 0.43 +/- 0.02, for six replicates). Indinavir sulphate was subjected to acid and alkali hydrolysis, oxidation, dry and wet heat treatment, and photo degradation. The drug undergoes degradation under acidic and basic conditions, oxidation, dry and wet heat treatment, and photo degradation. Also the degraded products were well resolved from the pure drug with significantly different Rf values. The method was validated for linearity, precision, robustness, limit of detection (LOD), limit of quantitation (LOQ), specificity and accuracy. Linearity was found to be in the range of 100-6000 ng/spot with significantly high value of correlation coefficient r2 = 0.997 +/- 0.64. The linear regression analysis data for the calibration plots showed good linear relationship with r2 = 0.999 +/- 0.002 in the working concentration range of 1000-6000 ng/spot. The LOD and LOQ were 40 and 120 ng/spot, respectively. Statistical analysis proves that the method is repeatable and specific for the estimation of the said drug. As the method could effectively separate the drug from its degradation products, it can be employed as a stability-indicating one. Moreover, the proposed HPTLC method was utilized to investigate the kinetics of acid degradation process. Arrhenius plot was constructed and activation energy was calculated.

HPTLC method for guggulsterone. I. Quantitative determination of E- and Z-guggulsterone in herbal extract and pharmaceutical dosage form.

A sensitive, selective, precise and robust high-performance thin-layer chromatographic method of analysis of E and Z stereoisomers of guggulsterone (the hypolipidemic agent in the gum-resin exudates of Commiphora mukul) both as a bulk drug and in formulations was developed and validated. The method employed TLC aluminium plates precoated with silica gel 60F-254 as the stationary phase. The solvent system consisted of toluene-acetone (9:1, v/v). Densitometric analysis of guggulsterone was carried out in the absorbance mode at 250 nm. This system was found to give compact spots for E- and Z-guggulsterone (Rf value of 0.38 +/- 0.02 and 0.46 +/- 0.02, respectively) following double development of chromatoplates with the same mobile phase. The linear regression analysis data for the calibration plots for E- and Z-guggulsterone showed good linear relationship with r2 = 0.9977 +/- 0.054 and 0.9975 +/- 0.068, respectively, in the concentration range of 100-6000 ng/spot. The mean value of slope and intercept were 0.11 +/- 0.006 and 0.11 +/- 0.005, 14.26 +/- 0.56 and 10.92 +/- 0.76, respectively, for E- and Z-guggulsterone. The method was validated for precision, robustness and recovery. The limit of detection and quantitation were 12, 10 and 24, 20 ng/spot, respectively, for E- and Z-guggulsterone. Statistical analysis proves that the method is repeatable and selective for the estimation of the said drug. Since the proposed mobile phase effectively resolves the E- and Z-isomers of guggulsterone, this HPTLC method can be applied for identification and quantitation of these isomers in herbal extracts and pharmaceutical dosage form.

HPTLC method for guggulsterone. II. Stress degradation studies on guggulsterone.

Stress degradation studies were carried out on guggulsterone (the hypolipidemic agent in the gum-resin exudates of Commiphora mukul) following the conditions prescribed in the parent drug stability testing guideline (Q1AR) issued by International Conference on Harmonization (ICH). The present study describes degradation of guggulsterone under different ICH prescribed stress conditions (acid and base hydrolysis, oxidation, dry and wet heat degradation and photodegradation) and establishment of a stability indicating HPTLC assay. The method employed TLC aluminium plates precoated with silica gel 60F-254 as the stationary phase. The solvent system consisted of toluene-acetone (9:1, v/v). Densitometric analysis of guggulsterone was carried out in the absorbance mode at 250 nm. This system was found to give compact spots for E- and Z-guggulsterone, (Rf value of 0.38 +/- 0.02 and 0.46 +/- 0.02, respectively) following double development of chromatoplates with the same mobile phase. The drug undergoes degradation under acidic and basic conditions, oxidation, dry and wet heat treatment and photodegradation. All the peaks of degraded products were resolved from the standard guggulsterone with significantly different Rf values. As the method could effectively separate the drug from its degradation products, it can be employed as a stability indicating one.

HPTLC method for determination of nevirapine in pharmaceutical dosage form.

A sensitive, selective, precise and stability-indicating high-performance thin-layer chromatographic method of analysis of nevirapine both as a bulk drug and in formulations was developed and validated. The solvent system consisted of toluene-carbon tetrachloride-methanol-acetone-ammonia (3.5:3.5:2.0:1.0:0.05, v/v/v/v/v). Densitometric analysis of nevirapine was carried out in the absorbance mode at 289nm. This system was found to give compact spots for nevirapine (R(f) value of 0.44+/-0.02). Nevirapine was subjected to acid and alkali hydrolysis, oxidation, dry heat and wet heat treatment and photodegradation. The drug undergoes degradation under acidic, basic conditions and oxidation. Also the degraded products were well resolved from the pure drug with significantly different R(f) values. Linearity was found to be in the range of 30-1000ng/spot with significantly high value of correlation coefficient. The linear regression analysis data for the calibration plots showed good linear relationship with r(2)=0.998+/-0.002 in the working concentration range of 300ng/spot to 1000ng/spot. The mean value of slope and intercept were 0.073+/-0.005 and 36.78+/-1.50, respectively. The method was validated for precision, robustness and recovery. The limit of detection and quantitation were 5 and 10ng/spot, respectively. As the method could effectively separate the drug from its degradation products, it can be employed as a stability indicating one. Moreover, the proposed HPTLC method was utilized to investigate the kinetics of acid degradation process. Arrhenius plot was constructed and activation energy was calculated.

Stability indicating HPTLC determination of linezolid as bulk drug and in pharmaceutical dosage form.

A simple, selective, precise, and stability-indicating high-performance thin layer chromatographic method of analysis of Linezolid both as a bulk drug and in formulations was developed and validated in pharmaceutical dosage form. The method employed TLC aluminium plates precoated with silica gel 60F-254 as the stationary phase. The solvent system consisted of toluene-acetone (5:5, v/v). This system was found to give compact spots for Linezolid (Rf value of 0.29 +/- 0.01). Linezolid was subjected to acidic, alkali hydrolysis, oxidation, and photodegradation. The degraded products also were well separated from the pure drug. Densitometric analysis of Linezolid was conducted in the absorbance mode at 254 nm. The linear regression data for the calibration plots showed good linear relationship with r2 = 0.997 +/- 0.001 in the concentration range of 300-800 ng/spot. The mean value of correlation coefficient, slope, and intercept were 0.998 +/- 0.003, 0.15 +/- 0.009, and 19.52 +/- 1.66 respectively. The method was validated for precision, accuracy, ruggedness, and recovery. The limits of detection and quantification were 20 ng/spot and 50 ng/spot, respectively. The drug undergoes degradation under acidic and basic conditions, oxidation and photo degradation. All the peaks of degraded product were resolved from the standard drug with significantly different Rf values. This indicates that the drug is susceptible to acid-base hydrolysis, oxidation, and photo degradation. Statistical analysis proves that the method is reproducible and selective for the estimation of the said drug. Because the method could effectively separate the drug from its degradation products, it can be used as a stability indicating one.

Stability-indicating HPTLC determination of tizanidine hydrochloride in bulk drug and pharmaceutical formulations.

A simple, selective, precise and stability-indicating high-performance thin-layer chromatographic method of analysis of tizanidine hydrochloride both as a bulk drug and in formulations was developed and validated. The method employed TLC aluminium plates precoated with silica gel 60F-254 as the stationary phase. The solvent system consisted of toluene-acetone-ammonia (5:5:0.1, v/v/v). This system was found to give compact spots for tizanidine hydrochloride (R(f) value of 0.32+/-0.01). Tizanidine hydrochloride was subjected to acid and alkali hydrolysis, oxidation and photodegradation. Also, the degraded product was well separated from the pure drug. Densitometric analysis of tizanidine hydrochloride was carried out in the absorbance mode at 315 nm. The linear regression analysis data for the calibration plots showed good linear relationship with r(2)=0.9922 in the concentration range 300-1000 ng per spot. The mean value of correlation coefficient, slope and intercept were 0.9922+/-0.002, 0.064+/-0.001 and 38.09+/-1.71, respectively. The method was validated for precision, recovery and robustness. The limits of detection and quantitation were 88 and 265 ng per spot, respectively. The drug does not undergo degradation under acidic and basic conditions. The samples degraded with hydrogen peroxide showed additional peak at R(f) value of 0.12. This indicates that the drug is susceptible to oxidation. Statistical analysis proves that the method is repeatable and selective for the estimation of said drug. As the method could effectively separate the drug from its degradation product, it can be employed as a stability-indicating one.

Preparation and characterization of glassy celecoxib.

Celecoxib, a poorly water-soluble drug, was converted into a glassy state by melt quenching. The properties of glassy celecoxib were studied using infrared (IR) spectroscopy, differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD), intrinsic dissolution rate (IDR), and thin-layer-chromatography (TLC). Glass transition occurred at 51.8 degrees C. Infrared spectrum of glass has revealed significant changes due to H-bonding. Celecoxib glass shows around 15 times faster dissolution as compared with the crystalline state. Heckel plot analysis has shown better compressibility in glassy state. Unpulverized glass remained stable for 3 months, whereas after pulverization about 70% crystallinity was gained in 100 hours. Further attempts may be carried out to stabilize the glass.

Stability indicating HPTLC determination of clopidogrel bisulphate as bulk drug and in pharmaceutical dosage form.

A sensitive, selective, precise and stability indicating high-performance thin layer chromatographic method of analysis of clopidogrel bisulphate both as a bulk drug and in formulations was developed and validated in pharmaceutical dosage form. The method employed TLC aluminium plates precoated with silica gel 60F-254 as the stationary phase. The solvent system consisted of carbon tetrachloride-chloroform-acetone (6:4:0.15, v/v/v). This system was found to give compact spots for clopidogrel bisulphate (R(f) value of 0.30+/-0.01). Clopidogrel bisulphate was subjected to acid and alkali hydrolysis, oxidation, photodegradation and dry heat treatment. Also the degraded products were well separated from the pure drug. Densitometric analysis of clopidogrel bisulphate was carried out in the absorbance mode at 230 nm. The linear regression data for the calibration plots showed good linear relationship with r(2)=0.999+/-0.001 in the concentration range of 200-1000 ng. The mean value of correlation coefficient, slope and intercept were 0.999+/-0.001, 0.093+/-0.011 and 8.83+/-0.99, respectively. The method was validated for precision, accuracy, ruggedness and recovery. The limits of detection and quantitation were 40 and 120 ng per spot, respectively. The drug undergoes degradation under acidic and basic conditions, oxidation and dry heat treatment. All the peaks of degraded product were resolved from the standard drug with significantly different R(f) values. This indicates that the drug is susceptible to acid-base hydrolysis, oxidation and dry heat degradation. Statistical analysis proves that the method is reproducible and selective for the estimation of the said drug. As the method could effectively separate the drug from its degradation products, it can be employed as a stability indicating one.

Spherical crystallization of celecoxib.

Celecoxib exhibits poor flow properties and compressibility. Spherical crystallization of celecoxib was carried out using the solvent change method. An acetone:dichloromethane (DCM):water system was used where DCM acted as a bridging liquid and acetone and water as good and bad solvent, respectively. Hydroxypropylmethylcellulose (HPMC) was used to impart strength and sphericity to the agglomerates. The effect of amount of bridging liquid and speed of agitation was studied using 3(2) factorial design. Primary properties of the agglomerates were evaluated by infrared spectroscopy, powder X-ray diffraction, and differential scanning calorimetry. The effect of variables on micromeritic, mechanical, compressional, and dissolution behavior was evaluated by response surface methodology. Particle size, bulk density, mean yield pressure (MYP), and drug release were found to be significantly affected by either of the two variables. Interaction of variables significantly affected the MYP.

Evaluation of dosage forms. IV. Studies on commercial phenylbutazone tablet dosage forms.

In order to determine the feasibility of dissolution-dialysis as a suitable technique for in vitro evaluation, studies on commercial phenylbutazone tablets were carried out. Although disintegration time and dissolution parameters did not give a true indication of bioavailability, an excellent correlation was obtained between the dialysis rate constant (K) and various pharmacokinetic parameters obtained from bioavailability studies on human volunteers.

Preliminary evaluation of Leucaena leucocephala seed gum as a tablet binder.

The seed galactomannan of Leucaena leucocephala Lam. de Wit var.K-8 (family Leguminosae), a natural polysaccharide, with properties comparable to guar gum, was evaluated as a pharmaceutical binder. Characterization was done using studies of compressibility, micromeritic, and mechanical properties of granules prepared by wet granulation and subsequent studies on compacts, both containing 5% w/w of binder. The seed gum was subsequently used as a binder with a badly compressible material, paracetamol, and studied likewise. The seed gum compared will with standard pharmaceutical binders (starch and polyvinyl pyrrolidone [PVP] K30), at least for properties studied herein.