Comparative bioavailability study of a new formulation of injection of 75 mg diclofenac sodium in 1 ml with the conventional injection of 75 mg diclofenac sodium given in 3 ml volume.

OBJECTIVES: Diclofenac a non-steroidal anti-inflammatory drug (NSAID) is widely used for the management of various musculoskeletal conditions. An injectable test formulation of diclofenac sodium (75 mg/mL) was prepared to facilitate reduction in injection volume as compared to already marketed formulations of diclofenac sodium (75 mg/3 mL). The objective of this study was to compare the bioavailability of test formulation with the reference formulation given intramuscularly in healthy volunteers. METHODS: This two way randomized crossover study was performed in 14 healthy, adult, Indian, male human subjects to compare bioavailability. The formulations were administered intramuscularly (intragluteal) to the volunteers in a two way randomized fashion with a wash out period of 6 days. Blood samples were collected till 6.0 h following drug administration. The samples were analyzed using pre-validated HPLC method. RESULTS: The mean Cmax and Tmax for the test and reference formulations were 2.14 µg/mL, 1.91 µg/mL and 0.49 h, 0.50 h respectively. The mean AUC(0-t) for test and reference formulations were 3.79 µg.h/mL, and 3.43 µg.h/mL respectively. The mean AUC(0-γ) for test and reference formulation were 4.03 µg.h/mL and 3.65 µg.h/mL respectively. The mean (90% CI) C(max), AUC(0-t) and AUC(0-γ) ratio (Test:Reference) were 1.15 (100.25-132.99), 1.10 (100.34-119.96) and 1.09 (100.78-118.88), respectively. CONCLUSION: The test formulation shows a comparable AUC(0-t) and AUC(0-γ) but a higher C(max) in comparison to the reference when given intra-gluteally. The lower volume of the test formulation offers advantage of injection at other sites, like deltoid region. Absence of propylene glycol in the test formulation could be advantageous in terms of improved tolerability. Hence, such formulations of previously well established molecules provide a new direction towards developing better and convenient dosing alternatives.

Pharmacokinetic profile of an intradeltoid diclofenac injection in obese Indian volunteers.

BACKGROUND: A new propylene glycol-free and reduced-volume formulation of diclofenac sodium 75 mg/mL designed for intradeltoid administration has been found to be bioequivalent to a reference formulation of diclofenac sodium 75 mg/3 mL given via the intragluteal route in normal healthy volunteers. Standard needles may not reach the gluteus maximus muscle in many cases, especially in the obese. The objective of this study was to determine the pharmacokinetic parameters of the new formulation and compare the bioavailability of intradeltoid diclofenac sodium 75 mg/mL with that of the intragluteal 75 mg/3 mL reference formulation in obese volunteers. METHODS: A comparative, two-way, single-dose, bioavailability study was carried out in 10 obese (body mass index > 25) male Indian volunteers after a washout period of seven days. Blood samples were collected until six hours following drug administration and analyzed using a prevalidated high-pressure liquid chromatography method. RESULTS: The mean maximum plasma concentration and time to reach maximum plasma concentration for the test formulation were 1.30 µg/mL and 0.50 hours, respectively, versus 0.93 µg/ mL and 1.08 hours for the reference formulation. The mean areas under the curve from 0 to last measurable time point (AUC(0-t)) for the test and reference formulations were 2.71 µg·h/mL and 2.73 µg·h/mL, respectively. The mean AUCs from 0 to infinity (AUC(0-∞)) for the test and reference formulations were 3.71 µg·h/mL and 3.75 µg·h/mL, respectively. CONCLUSION: The results suggest that the test formulation of diclofenac sodium 75 mg/mL has an AUC(0-t) and AUC(0-∞) comparable with the reference intragluteal formulation of diclofenac sodium 75 mg/3 mL, but with an earlier time to reach maximum plasma concentration and a trend towards a higher maximum plasma concentration. This could be attributed to faster absorption from the deltoid region than from the gluteal region. The test formulation could be helpful in the management of pain in obese or overweight patients and those with dense subcutaneous fat in the gluteal area.

Simultaneous HPLC-UV determination of rhein and aceclofenac in human plasma.

Diacerein and aceclofenac are prescribed for reducing the symptoms associated with osteoarthritis. We present a simple HPLC method with UV detection for simultaneous determination of rhein (the immediate metabolite of diacerein) and aceclofenac from human plasma samples. Sample preparation was accomplished through liquid-liquid extraction with ethyl acetate and chromatographic separation was performed on a reversed-phase ODS column. Mobile phase consisted of a mixture of acetate buffer and acetonitrile run under gradient at flow rate of 1.0 ml/min. Wavelength was set at 258 nm. The method was validated for linearity, accuracy, precision and stability. The calibration was linear over the range of 0.1-7.0 microg/ml for rhein and 0.5-20 microg/ml for aceclofenac using 500 microl plasma samples. Extraction recoveries were 85% for rhein and 70% for aceclofenac. The method can easily be adopted for high-throughput clinical and pharmacokinetic studies of above two-drug fixed dose combination formulations.

Pharmacokinetic profile of a new formulation of injection diclofenac designed for intradeltoid use.

OBJECTIVE: Injection diclofenac sodium available at present as a 3-ml formulation is administered intragluteally. Standard needles may not reach the gluteus maximus muscle in many cases, especially in obese patients. Alternative sites like the deltoid have been suggested to be more suitable for these patients. Diclofenac sodium 75 mg/ml was prepared to facilitate intradeltoid administration. The objective of this study was to determine pharmacokinetic parameters and to compare the bioavailability of the new formulation of injection diclofenac sodium (75 mg/ml), given as an intradeltoid injection, with the reference formulation (75 mg/3 ml) given intragluteally. RESEARCH DESIGN/METHODS: A single-dose, two-way bioequivalence study was carried out in 18 healthy, Indian, male volunteers with a washout period of 5 days. Blood samples were collected up to 6 h after drug administration and analyzed using a prevalidated HPLC method. RESULTS: The mean C(max) and T(max), for the test and reference formulations were 1.95 microg/ml, 1.89 microg/ml and 0.39 h, 0.43 h respectively. AUC values from 0 to last measurable time point 't' observed for test and reference formulations were 3.37 microg.h/ml and 3.28 microg.h/ml respectively. The mean AUC 0 - infinity for test and reference formulations was 3.57 microg.h/ml and 3.52 microg.h/ml. CONCLUSION: Results suggest that the test and reference formulations of injection diclofenac sodium 75 mg given intradeltoid and intragluteally are bioequivalent. The test formulation would be especially helpful in the management of obese/overweight patients and patients with thick subcutaneous fat in the gluteal region. It would increase the success rate of intramuscular deposition of the medication.

Quantification of 4-methylaminoantipyrine, the active metabolite of dipyrone, in human plasma.

BACKGROUND: Dipyrone (metamizole) is a nonsteroidal anti-inflammatory drug used as an analgesic and antipyretic in both pediatric and adult patients. Dipyrone hydrolyses to 4-methylaminoantipyrine (MAA) in the stomach before absorption. There are several HPLC methods available for analysis of MAA from human plasma but no method has yet been developed on liquid chromatography-mass spectrometry (LC-MS) or LC tandem MS (LC-MS/MS), which are much more specific and sensitive techniques. METHODOLOGY: A high-performance LC-MS method for the quantification of 4-methylaminoantipyrine from human plasma has been developed, validated and applied to a pharmacokinetic study of 500 mg oral dose dipyrone. Following liquid-liquid extraction, the analyte was first separated on a reverse phase column using isocratic mobile phase and then analyzed by MS in selected ion monitoring mode using [M+H](+) ions, m/z 218.2 for 4-methylaminoantipyrine and 231.3 for 4-isopropylantipyrine (internal standard). RESULTS: The method exhibited a linear range from 0.2 to 10.0 µg/ml when only 100 µl human plasma sample was used. The lower limit of detection was 0.04 µg/ml (160 pg on column). The recovery was 80%. The accuracy and precision were obtained over the calibration curve range and were well within the limits specified under guidelines for bioanalytical method validation. The compound was stable under the experimental conditions. CONCLUSION: The method was demonstrated to be, simple, sensitive and rapid. It can be easily adopted in laboratories with access to LC-MS or MS/MS and applied to sample analysis in clinical settings where a large number of samples are generated.

Determination of pitavastatin from human plasma using high performance liquid chromatography with fluorescence detection.

Pitavastatin belongs to the class of coenzyme A reductase inhibitors. Very few methods of assaying pitavastatin from human plasma are available in literature. An analytical method is presented for the determination of the drug from human plasma making use of the fluorescent property of the drug. The drug is extracted from plasma using ethyl acetate under neutral condition and then analyzed by reversed-phase high performance liquid chromatography (HPLC) with fluorescence detection (lambda(Ex) 245 nm; lambda(Em) 420 nm). Analysis of pitavastatin was carried out on a C18 HPLC column using a gradient flow of mobile phase (0.01 mol/L monobasic potassium phosphate (pH 3.20) -acetonitrile, 63:37, v/v). Fluorescein isothiocyanate was used as internal standard. The dynamic range of assay was 3 to 50 ng/mL. The intraday precision was less than 10% and accuracy ranged from 95.2% to 112.6%. The same for interday check was less than 12% and 92.8% to 105.1%, respectively. The drug was found to be stable under the assay conditions. The developed method is simple, precise, accurate, and stable. This indicates that it can be applied to routine analysis of this drug in human subjects where there are large numbers of samples without the need of specialized instruments like column switching.