Preparation and in vitro/in vivo evaluation of metformin hydrochloride rectal dosage forms for treatment of patients with type II diabetes.

BACKGROUND: Metformin hydrochloride (MtHCL) is an oral antidiabetic drug and has many other therapeutic benefits. It has poor bioavailability, narrow absorption window and extensive liver metabolism. Moreover, children and elders face difficulty to swallow the commercial oral tablets. OBJECTIVES: Preparation, in vitro/in vivo evaluation of MtHCL suppositories for rectal administration to solve some of these problems. METHODS: Suppository fatty bases (Witepsol®, Suppocire® and Massa®; different grades) and PEG bases 1000, 4000 and 6000 (different ratios), were used to prepare rectal suppository formulations each containing 500 mg drug. These were characterized for manufacturing defects, and pharmacotechnical performance and formulations showing superior results were subjected to bioavailability testing in human volunteers compared with the commercial oral tablet (Ref) applying LC-MS/MS developed analytical technique. RESULTS: The preparation method produced suppositories with satisfactory characteristics and free of manufacturing defects. The fatty bases were superior compared with PEG bases regarding the physical characteristics. Three formulations were chosen for bioavailability testing and the results showed comparable bioavailability compared to the Ref. CONCLUSIONS: The fatty bases showed superior characteristics compared with the PEG bases. MtHCL formulated in selected fatty bases could be a potential alternative to the commercial oral tablets particularly for pediatric and geriatric patients.

In vitro and in vivo permeation of vitamin E and vitamin E acetate from cosmetic formulations.

OBJECTIVE: To investigate the ability of α-tocopherol acetate (TA) and α-tocopherol (T), widely used ingredients in cosmetics, to cross the epidermal barrier using the neonatal rat as a model. MATERIALS AND METHODS: The content of T and TA in four marketed products (A-D) and two experimental formulations (F1, F2) was investigated by HPLC. An in vitro permeation study was performed in neonatal rat epidermis using diffusion cells. In vivo permeation was studied in neonatal rats after repeated application of the products and analysis of T and TA in the stratum corneum/deeper skin layers. RESULTS: Variable contents of TA were found in the marketed products (0.12-0.53%). No vitamin permeation was detected through the stratum corneum as in vitro biological barrier after 4 h. No detectable T and TA were seen in the in vivo permeation study in the epidermis. Variable degrees of drug penetration (4.3-12.6%) of the applied dose into the deeper skin layers were observed, depending on the formulation. In vivo application of TA-containing preparations did not result in any transformation of TA into T under the described experimental conditions. CONCLUSION: TA and T exhibited variable skin penetration and TA did not transform into T under the experimental conditions. The data underscored the need for further studies to optimize such formulations to improve vitamin E transdermal permeation and eventually achieve the expected cosmetic/therapeutic outcome.

Analysis of vitamin E in commercial cosmetic preparations by HPLC.

A specific HPLC method, with an RP-C-18 column and a UV detector, for simultaneous determination of vitamin E (tochopherol, T)/T acetate (TA) in four commercial and two experimental cosmetic products is described. Three solvent systems for extraction of T/TA were assessed: isopropyl alcohol; 10:90 v/v hexane-methanol mixture (method 1); and methanol alone (method 2). The procedure was accurate, as indicated by high recovery (97.8-101.8% and 100.1-102.5% for T and TA, respectively) and precise (RSD was only 0.9-3.26% and 0.73-3.35% for T and TA, respectively). The limits of detection for T and TA were 200 and 300 ng/ml, respectively, while the limits of quantitation were 250 and 400 ng/ml, respectively. The range of reliable quantification was 5-50 µg/ml. Isopropanol as solvent resulted in a turbid extract. Method 1 and method 2 of extraction showed high recovery (98.5-99.9% and 97.2-97.9% for T and TA, respectively). After a few weeks of analysis, method 1 resulted in retention time drift, peak broadening, non-reproducible results, and progressive loss of HPLC-column integrity. Methanol alone (method 2) was equally as efficient as that of the mixture of methanol with 10% hexane (method 1) for extraction. The described analytical procedure proved to be accurate, precise, and suitable for simultaneous determination of T and TA in real commercial cosmetic products.

Physicochemical characterization of gliclazide-macrogol solid dispersion and tablets based on optimized dispersion.

BACKGROUND: This study investigated the physical interaction of gliclazide (GLC) with a hydrophilic carrier, that is, macrogol [polyethylene glycol (PEG)]. Different molecular weights of PEG (4000, 10,000, and 20,000) were used in different drug : carrier weight ratios (1 : 1, 1 : 2, 1 : 5, and 1 : 10). METHOD: Preliminary screening was done by phase solubility studies to characterize the liquid state interaction between the drug and the carrier. Solid dispersions (SDs) of GLC and PEG in different ratios were prepared by fusion technique and by physical mixing. The solid-state interaction between the drug and the carrier was examined by performing differential scanning calorimetry and Fourier transform infrared spectroscopic studies. SD with satisfactory characteristics was selected for the formulation of tablets by wet granulation method and compared with the commercial brand for in vitro dissolution. RESULTS: It was evident from phase solubility studies that the drug solubility increased linearly with increasing PEG concentrations. In vitro dissolution of GLC improved significantly in the SDs prepared by fusion method as compared with the original drug and physical mixtures. Scanning electron microscopy images showed well-defined changes in the surface topography of GLC, thus confirming the effective formation of a fused binary system. The SD tablets showed a significant improvement in the drug release profile than that of the commercial brand. CONCLUSION: It was thus concluded that SD formulations of GLC can be successfully used to design a solid dosage form of the drug, which would have significant advantages over the current marketed tablets.

Comparison between lipolysis and compendial dissolution as alternative techniques for the in vitro characterization of alpha-tocopherol self-emulsified drug delivery systems (SEDDS).

In vitro characterization of alpha-tocopherol SEDDS formulations was performed by (1) lipolysis in bio-relevant media, and (2) physical assessment by dissolution, particle size, and turbidity analyses. Both methods were statistically correlated using a 25-run, five-factor multiple-level d-optimal mixture design. Independent variables were SEDDS composition [vitamin E (12.5-25%), Tween 80 (10-40%), labrasol (0-10%), alcohol (0-10%), and captex 355 (20-50%)]. Measured responses were percent lipolysis, percent vitamin E retained in the aqueous layer of the digestion medium, and percent vitamin E dissolved in the dissolution medium. Percent lipolysis ranged from 0% to 66.3%. Percent vitamin E retrieved in the aqueous layer of the digestion and dissolution media ranged from 3% to 29.3% and from 25.9% to 101.7%, respectively. Turbidity ranged from 28 to 403JTU and the average droplet size was >1.0 microm. All formulation ingredients had significant (p<0.05) effect on percent lipolysis. Only two factors, Tween and vitamin E had significant effect on vitamin retention in the aqueous layer post-lipolysis. Tween, labrasol, and captex 355 had significant effect on vitamin E dissolution. Poor correlation was observed between the responses. Formulation ingredients influenced each response differently; and therefore, each method can only reveal distinctive characteristics of the SEDDS formulation and may not be used interchangeably.

Bioavailability assessment of vitamin A self-nanoemulsified drug delivery systems in rats: a comparative study.

OBJECTIVES: To assess and compare the bioavailability of three different oral dosage forms of vitamin A in rats. The formulations included vitamin A self-nanoemulsified drug delivery (SNEDD) optimized formulation-filled capsule (F1), vitamin A SNEDD optimized formulation compressed tablet (F2) and vitamin A oily solution-filled capsules without any additives (control, F3). MATERIALS AND METHODS: Bioavailability was assessed after a single oral dose of the three formulations using three groups of rats, each group comprising 6 rats. Blood samples were collected at baseline and over the next 8 h. Plasma was separated and extracted to obtain the drug, which was measured by HPLC. Statistical data analysis was performed using the Student t test and ANOVA with p < 0.05 as the minimal level of significance. RESULTS: From the pharmacokinetic parameters, both F1 and F2 showed improved bioavailability compared to F3. The values of AUC +/- SD were 3,080.7 +/- 190.2, 2,137.1 +/- 130.5 and 1,485.2 +/- 80.1 ng x h/ml for F1, F2 and F3, respectively. The Tmax was 1 h in case of F1 and F2 as compared to 1.5 h for F3. The Cmax +/- SD was 799.5 +/- 48.5, 656.2 +/- 64.4 and 425.8 +/- 33.1 for F1, F2 and F3, respectively. The increase in AUC, Cmax and Tmax was significant (p < 0.05). The bioavailability calculated from the AUC for F1 and F2 relative to F3 was 207.4 and 143.8%, respectively. The bioavailability increased almost twofold and 1.4 times for F1 and F2, respectively. CONCLUSIONS: The study showed that the newly developed vitamin A SNEDD formulations increased the rate and extent of drug absorption compared to the oily drug solution. The present investigation demonstrated that vitamin A SNEDD optimized formulations, either as filled capsules or as compressed tablets, were superior to its oily solution with regard to their biopharmaceutical characteristics.

Response surface methodology to obtain beta-estradiol biodegradable microspheres for long-term therapy of osteoporosis.

The purpose of this work was to evaluate the main and interaction effects of formulation factors on the drug encapsulation efficiency of beta-estradiol biodegradable microspheres by applying response surface methodology. A secondary purpose was to obtain an optimized formula for long-term therapy of osteoporosis. A three factor, three level Box-Behnken experimental design was used to get 15 experimental runs. The independent variables were drug/polymer ratio (X1), dispersing agent concentration (X2), and deaggregating agent concentration (X3). The dependent variables were percentage encapsulation efficiency (Y1), cumulative percent drug released (Y2), and percentage yield of the microspheres (Y3). The formulations were prepared by emulsion solvent evaporation technique using ethyl acetate as organic solvent. The optimized formulation was maximized for encapsulation efficiency and further characterized for the particle size distribution, scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FT-IR). The mathematical relationship obtained between X1, X2, X3, and Y1 was: Y1 = -129.85 + 29.35X1 + 129.99X2 + 64.82X3 - 3.2X1X2 - 0.29X1X3 - 35.83X2X3 - 2.05X(2)(1) - 13.23X(2)(2) - 5.92X(2)(3) (R2 = 0.99) The equation showed that X1, X2, and X3 affect Y1 positively but interaction between any two of these factors affects Y1 negatively. The most significant interaction was between X2 and X3. The finding indicated that controlled releases beta-estradiol biodegradable microspheres with high encapsulation efficiency and low pulsatile release can be prepared and the quantitative response surface methodology applied helped in understanding the effects and the interaction effects between the three factors applied.

Biodegradable microparticulates of beta-estradiol: preparation and in vitro characterization.

Beta-estradiol has been recommended for the long-term therapy of osteoporosis and its oral formulations are subjected to intensive first pass metabolism. The present investigation was aimed at preparing and characterizing biodegradable microparticles of beta-estradiol with polymers such as PLA, PLGA 85/15, PLGA 75/25, and their mixtures. The microparticles were prepared by solvent evaporation method using methylene chloride as a solvent and polyvinyl alcohol as a surfactant. The drug-polymer ratios were 1:3, 1:5, and 1:7. The prepared microparticles (twelve formulations) were tested for encapsulation efficiency and in vitro drug release in 50% methyl alcohol/phosphate buffer pH 7.4. The results showed that the encapsulation efficiency varied from 81 to 100% and the formulation fabricated from PLGA 85/15 (1:3) showed less burst and consistent long time release. This formulation when further characterized displayed irregular spherical shape with an average particle size of 72 microm. The crystallinity of the drug was reduced when investigated using X-ray diffractometry. No chemical interaction between the drug and the polymer was observed as evidenced by FT-IR analysis. The results indicated that beta-estradiol biodegradable microparticles with PLGA 85/15 (1:3) could be a suitable approach for long term therapy of osteoporosis.

Pulmonary absorption of insulin mediated by tetradecyl-beta-maltoside and dimethyl-beta-cyclodextrin.

PURPOSE: To determine if tetradecyl-beta-maltoside (TDM) and dimethyl-beta-cyclodextrin (DMbetaCD) enhance pulmonary absorption of insulin and to investigate if they do so by a reversible action on respiratory epithelium. METHODS: Insulin formulated with saline, TDM, or DMbetaCD was administered intratracheally, after laryngoscopic visualization, as a spray to anesthetized rats. Reversibility studies were conducted in intact rats by administering insulin at different time points after administration of TDM or DMbetaCD. The pharmacodynamics and pharmacokinetics of insulin formulations were assessed by measuring plasma glucose and plasma insulin concentrations. RESULTS: When insulin formulated with increasing concentrations (0.06-0.25%) of TDM or DMbetaCD were administered to anesthetized rats, there was a concentration-dependent decrease in plasma glucose and increase in plasma insulin concentrations. The relative bioavailability of insulin formulations containing TDM was higher (0.34-0.84%) than that of formulations containing DMbetaCD (0.19-0.48%). When insulin was administered 120 min after an agent was administered, in the reversibility study, no significant change in plasma glucose and insulin levels occurred compared to control. CONCLUSIONS: Both TDM and DMBCD enhance pulmonary absorption of insulin, with TDM being more efficacious than DMbetaCD in enhancing insulin absorption via pulmonary administration. The effects of TDM and DMbetaCD on respiratory epithelium are reversible, and the epithelium reestablishes its normal physiologic barrier 120 min after exposure to these agents.

Salbutamol sulfate suppositories: influence of formulation on physical parameters and stability.

PURPOSE: To prepare and evaluate a suppository dosage form of salbutamol sulfate. The prepared formulae with and without different concentrations of gels were tested for hardness, melting time, content uniformity, and drug release. The stability of some of the selected formulae was assessed. METHODS: Salbutamol sulfate was formulated as a rectal suppository with emulsifying fatty bases (suppocire and witepsol) and water-soluble bases (PEG) adopting the molding from a melt technique. Physical characteristics and dissolution profiles of the prepared formulations were determined as the responses. The effects of adding gels, methyl cellulose (MC), and Eudispert (Eud) and their concentrations (1, 3, and 6%) on these responses were also investigated. Formulations showing high rank order were scaled up for shelf-life stability study for one year. RESULTS: The results showed that all the investigated formulae have acceptable physical characteristics with respect to hardness, melting time (except F7), and uniformity of drug content. The amount of drug dissolved in 100 min of dissolution time was inversely affected by the melting point of the fatty base. The release from PEG bases was found to be molecular weight dependent. Addition of 1% MC or Eud gel increased the release from all the investigated formulae. Increasing gel concentration to 3% then to 6% showed different effects on the release. The degradation of salbutamol sulfate in the investigated formulae was found to be a first-order reaction. CONCLUSIONS: Rectal suppository of salbutamol sulfate could be prepared as an alternative to the oral dosage form to circumvent the first-pass metabolism.

Development of a HPLC method for the determination of cyclosporin-A in rat blood and plasma using naproxen as an internal standard.

An isocratic reversed phase high-performance liquid chromatographic (HPLC) method with ultraviolet detection at 205 nm has been developed for the determination of cyclosporin-A (CyA) in rat blood and plasma. Naproxen was successfully used as an internal standard. Blood or plasma samples were pretreated by liquid-liquid extraction with diethyl ether. The ether extract was evaporated and the residue was reconstituted in acetonitrile-0.04 M monobasic potassium phosphate buffer (pH 2.5) solvent mixture. After washing with n-hexane, 30 microl of the reconstituted solution was injected into HPLC system. Good chromatographic separation between CyA and internal standard peaks was achieved by using a stainless steel analytical column packed with 4 microm Nova-Pak Phenyl material. The system was operated at 75 degrees C using a mobile phase consisting of acetonitrile-0.04 M monobasic potassium phosphate (pH 2.5) (65:35 v/v) at a flow rate of 1 ml/min. The calibration curve for CyA in rat blood was linear over the tested concentration range of 0.0033-0.0166 M with a correlation coefficient of 0.989. For rat plasma, the range of the concentrations tested were between 0.002 and 0.0166 M and showed linearity with a correlation coefficient of 0.953. The intra- and inter-run precision and accuracy results were 1.24-21.87 and 3.1-12.23%, respectively. The low volume of blood or plasma needed (200 microl), simplicity of the extraction process, short run time (5 min) and low injection volume (30 microl) make this method suitable for quick and routine analysis.

Effect of Azone upon the in vivo antiviral efficacy of cidofovir or acyclovir topical formulations in treatment/prevention of cutaneous HSV-1 infections and its correlation with skin target site free drug concentration in hairless mice.

The purpose of this study is to examine the influence of Azone upon the skin target site free drug concentration (C(*)) and its correlation with the in vivo antiviral efficacies of cidofovir (HPMPC) and acyclovir (ACV) against HSV-1 infections. Formulations of HPMPC and ACV with or without Azone were used. The in vitro skin flux experiments were performed and the C(*) values were calculated. For the in vivo efficacy studies, hairless mice cutaneously infected with HSV-1 were used and three different treatment protocols were carried out. The protocols were chosen based upon when therapy is initiated and terminated in such a way to assess the efficacy of the test drug to cure and/or prevent HSV-1 infections. A finite dose of the formulation was topically applied twice a day for the predetermined time course for each protocol and the lesions were scored on the fifth day. For ACV formulation with Azone, the C(*) values and hence the in vivo efficacy were much higher than those for that without Azone. In protocol #1, however, early treatment did not increase the in vivo efficacy of ACV when compared with the standard treatment protocol #3. In protocol #2 where the treatment was terminated on the day of virus inoculation, the efficacies for both ACV formulations were completely absent. Although the estimated C(*) values for HPMPC formulations with and without Azone were comparable, formulation with Azone was much more effective than that without Azone in all treatment protocols. HPMPC formulations with Azone at similar flux values were much more effective in "treating and preventing" HSV-1 infections than those without Azone. For ACV formulations, in contrast, addition of Azone has failed to show any effect on the preventive in vivo antiviral efficacy and the enhancement of ACV in vivo antiviral efficacy was merely the skin permeation enhancement effect of Azone.

Bioavailability assessment of oral coenzyme Q10 formulations in dogs.

The purpose of this investigation was to compare the bioavailability of three coenzyme Q10 (CoQ10) formulations in dogs using an open, randomized, multiple-dose crossover design. The formulations included a powder-filled capsule (A, control) and two soft gelatin formulations (Q-Gel as the water-miscible form of CoQ10, B and Q-Nol as the water-miscible form of ubiquinol, the reduced form of CoQ10, C). Formulations were evaluated in pairs, allowing a washout period of 14 days prior to crossing over. Blood samples were collected from each animal prior to dosing to determine the endogenous plasma CoQ10 concentrations. Serial blood samples were collected for 72 hr and plasma CoQ10 concentrations were determined by high-performance liquid chromatography. Plasma concentration-time profiles were corrected for endogenous CoQ10 concentrations. Results showed that the relative bioavailabilities of formulations B and C were approximately 3.6 and 6.2-fold higher than that of control formulation A. The AUC(microgram.hr/mL) +/- SD, Cmax(microgram/mL) +/- SD, and Tmax(hr) +/- SD for formulations A, B, and C were 1.695 +/- 0.06, 6.097 +/- 0.08, and 10.510 +/- 0.10; 0.096 +/- 0.035, 0.169 +/- 0.038, and 0.402 +/- 0.102; and 4.2 +/- 1.48, 4.1 +/- 1.57, and 4.5 +/- 0.58, respectively. While no significant differences were observed between Tmax values of the three formulations, the AUC and Cmax values for formulations B and C were significantly higher than those of the control (p < 0.05). The present investigation demonstrates that soft gelatin capsules containing water-miscible CoQ10 formulations B (Q-Gel) and C (Q-Nol) are superior to powder-filled formulations with regard to their biopharmaceutical characteristics.