Mechanism of in vitro percutaneous absorption enhancement of carvedilol by penetration enhancers

The effect of penetration enhancers like tulsi (basil) oil, eucalyptus oil, clove oil, black cumin oil, oleic acid and Tween 80 on the percutaneous absorption of model lipophilic drug-carvedilol was investigated using excised rat abdominal skin. Transdermal flux, permeability coefficient and enhancement factor were calculated for each penetration enhancer. Black cumin oil (5% v/v) was selected on the basis of its highest enhancement in permeation and was evaluated further for its mode of action using DSC, FTIR and histological studies. The results indicated that the oil shows its action by extraction of lipids from stratum corneum as well as by loosening the hydrogen bonds between ceramides subsequently leading to fluidization of the lipid bilayer.

Transdermal Delivery of Flurbiprofen: Permeation Enhancement, Design, Pharmacokinetic, and Pharmacodynamic Studies in Albino Rats

The enhancing effects of lemon oil on the transdermal penetration of flurbiprofen through rat skin invitro and in vivo was investigated. The maximum flux achieved by Isopropyl alcohol (IPA):Propylene glycol (PG) (70:30% v/v) solvent mixture was further increased by lemon oil. The flux of flurbiprofen through ethylene vinyl acetate microporous membrane was evaluated. The membrane altered the flux of flurbiprofen significantly. The reservoir type of transdermal patch was fabricated using flurbiprofen viscous system, ethylene vinyl acetate membrane, and backing film. Histological investigations were done on rat skin samples treated with solvent systems with or without penetration enhancer for 24 hr. No skin irritation was seen. Lemon oil produced more pronounced change in stratum corneum and the epidermis as compared with the control groups. The pharmacokinetics of flurbiprofen in albino rats following application of a transdermal patch for 24 hr was evaluated. The maximum plasma concentration (C(max)) and AUC(0-alpha) of the patch formulation was 1.7 and 1.6 times, increased respectively as compared with the control patch formulation. Quantity of the drug accumulated in the excised skin to which test patch formulation was applied was more than the one to which control patch formulation was applied. Anti-inflammatory effect in the Carrageenin-induced paw edema in rat was significantly higher than the control patch formulation.

In-vivo evaluation in rats of colon-specific microspheres containing 5-fluorouracil

The aims of this investigation were to determine the distribution in the gastrointestinal (GI) tract of Eudragit S-100 encapsulated colon-specific sodium alginate microspheres containing 5-fluorouracil (5-FU) in rats, and to perform pharmacokinetic and pharmacodynamic studies. Comparisons were with a control immediate-release (IR) formulation of 5-FU. 5-FU was distributed predominantly in the upper GI tract from the IR formulation but was distributed primarily to the lower part of the GI tract from the microsphere formulation. No drug was released in the stomach and intestinal regions from the colon-specific microspheres. Significantly, a high concentration of the active drug was achieved in colonic tissues from the colon-specific microspheres (P < 0.001), which was higher than the IC50 required to halt the growth of and/or kill colon cancer cells. Colon cancer was induced in rats by subcutaneous injection of 1,2-dimethylhydrazine (40 mg kg (-1)) for 10 weeks. The tumours induced were non-invasive adenocarcinomas and were in Duke's stage A. The 5-FU formulations were administered for 4 weeks after tumour induction. Non-significant reductions in tumour volume and multiplicity were observed in animals given the colon-specific microspheres. Enhanced levels of liver enzymes (SGOT, SGPT and alkaline phosphatase) were found in animals given the IR formulation of 5-FU, and values differed significantly (P < 0.001) from those in animals treated with the colon-specific microspheres. Elevated levels of serum albumin and creatinine, and leucocytopenia and thrombocytopenia were observed in the animals given the IR formulation. In summary, Eudragit S-100 coated alginate microspheres delivered 5-FU to colonic tissues, with reduced systemic side-effects. A long-term dosing study is required to ascertain the therapeutic benefits.

Microemulsions as potential drug delivery systems: a review

By many estimates, up to 40 percent of new chemical entities discovered by the pharmaceutical industry are poorly soluble or lipophilic compounds. Solubilization of hydrophobic drugs with low aqueous solubility has been a major area of interest in recent years. Various solubilization techniques involve the use of co-solvents and surfactants along with pH adjustments. Applications of microemulsions have also drawn attention in the field of solubilization techniques. Microemulsions are optically isotropic and thermodynamically stable systems consisting of water, oil, a surfactant, and a co-surfactant and are known to enhance the bioavailability of drugs via topical and systemic routes. The objective of this review is to present briefly the possible applications of these novel systems of microemulsions. Most studies reported in the literature have investigated microemulsions intended for dermatological application because of the wider range of potential excipients.

Nanoemulsion system for the transdermal delivery of a poorly soluble cardiovascular drug

The purpose of the present study is to develop and evaluate the potential of nanoemulsions for increasing the solubility and the in vitro transdermal delivery of carvedilol. Pseudoternary phase diagrams were developed and various nanoemulsion formulations were prepared using oleic acid and isopropyl myristate (IPM) (1:1) as the oil, Tween 80 as surfactant, and Transcutol P as cosurfactant. The prepared nanoemulsions were subjected to physical stability tests. Transdermal permeation of carvedilol through rat abdominal skin was determined with Keshary-Chien diffusion cell. Significant increase (P < 0.05) in the steady state flux (Jss) and permeability coefficient (Kp) was observed in nanoemulsion formulations as compared to control or drug-loaded neat components. The highest value of these permeability parameters was obtained in optimized formulation B3, which consisted of 0.5% w/w of carvedilol, 6% w/w of oleic acid:IPM (1:1), 22.5% w/w of Tween 80, 22.5% w/w of Transcutol P, and 49% w/w of distilled water and in which the solubility of the drug was 4500-fold higher. The optimized nanoemulsion was characterized for pH, conductivity, viscosity, droplet size, droplet shape, and refractive index. Thermodynamic studies showed that there had been a significant decrease of 88% in activation energy (Eact) when the drug was incorporated in nanoemulsion. The irritation studies suggested that the optimized nanoemulsion was a non-irritant transdermal delivery system.

Development and evaluation of a microemulsion formulation for transdermal delivery of terbinafine

The aim of the present study is to develop and evaluate microemulsion formulations for Terbinafine (TB) with a view to enhance its permeability through the skin and provide release for 24 h. Various o/w microemulsions were prepared by the spontaneous emulsification method. Oleic acid was chosen as the oil phase, Caprylo caproyl macrogol-8- glyceride (Labrasol S) and purified diethylene glycol monoethyl ether (Transcutol P) were used as surfactant and cosurfactant, respectively, on the basis of solubility studies. Pseudoternary phase diagrams were constructed to obtain the concentration range of oil, surfactant, cosurfactant, and water for microemulsion formulation. The optimized microemulsion consisted of 2% w/w TB, 8% w/w oleic acid, 31% w/w labrasol S, 31% w/w transcutol P, and 30% w/w distilled water. Permeability parameters like Jss and Kp were found to be significantly higher for formulation F4 as compared to other formulations (P < 0.05). Microbiological studies of TB in microemulsion showed better anti-fungal activity against Candida albicans and Aspergillus flavus as compared to marketed product (P < 0.05).

Effect of pre-treatment of almond oil on ultraviolet B?induced cutaneous photoaging in mice

BACKGROUND

Ultraviolet (UV) radiation has been implicated in photoaging and various types of skin carcinomas. Although the human skin has evolved several defense mechanisms to survive the insults of actinic damage like keratinization, melanin pigmentation, etc., it is still subjected to the harmful effects of sunlight.

AIMS

In this study, the role of almond oil in reducing the degradative changes induced in skin upon exposure to UV radiation was investigated.

METHODS

Mice were divided in four groups of 20 animals. Group I was the control group. Group II was negative control, which received almond oil treatment alone. Group III was exposed to UV radiation only and Group IV received both UV treatment and almond oil treatment. Visible skin grading assessed the changes based on a rating scale, biochemical tests (glutathione estimation and lipid peroxidation), and histopathologic studies.

RESULTS

Upon exposure of mice to UV radiation, it was found that pronounced visible skin changes were seen after 12 weeks of exposure. The results of the biochemical tests, glutathione estimation, and lipid peroxidation showed that almond oil reduced the effect of UV light-induced photoaging on the skin. Histopathologic studies also indicated a photoprotective effect of almond oil on the skin after UV exposure.

CONCLUSIONS

It was concluded that topical almond oil is capable of preventing the structural damage caused by UV irradiation and it was also found useful in decelerating the photoaging process.

A reverse phase high performance liquid chromatography method for simultaneous estimation of melatonin, carbamazepine epoxide and carbamazepine simultaneously in serum

Monitoring of plasma antiepileptic drugs is useful for better clinical management in epileptic patients, particularly in children. Carbamazepine (CBZ) is one of the commonly prescribed anticonvulsants. The active metabolite of carbamazepine-carbamazepine-10-11 epoxide (CBZ-Epo) also exhibits anticonvulsant effect. The pineal hormone, melatonin exerts an anticonvulsant effect in experimental seizure models and recently has also been used in cases of childhood epilepsy. To facilitate the simultaneous plasma estimation of carbamazepine, carbamazepine epoxide, and melatonin, a new HPLC method was developed. Waters millennium 2010 chromatography manager with a 515 HPLC pump and Waters 24879 dual absorbance UV detector was used. A 25 microlitre of sample and standards were injected, and chromatographic separation was achieved by Merck C18 reverse phase column particle size 5 micro, 250 mm x 4 mm. It was quantitated at UV light 210 nm. The retention times of melatonin, CBZ-Epo, and CBZ were 6.3 min, 7.5 min, and 13.9 min respectively. The Mobile Phase used was water: acetonitrile (70:30), pH 3.0 adjusted with orthophosphoric acid at the flow rate of 1 ml/min. The limits of detection of melatonin, carbamazepine epoxide, and carbamazepine were 800, 500, and 1300 pg respectively.

Stability indicating high-performance thin-layer chromatographic determination of gatifloxacin as bulk drug and from polymeric nanoparticles

A simple, sensitive, selective, precise and stability indicating high-performance thin-layer chromatographic method for determination of gatifloxacin both as a bulk drug and from polymeric nanoparticles was developed and validated as per the International Conference on Harmonization (ICH) guidelines. The method employed thin-layer chromatography (TLC) aluminium plates precoated with silica gel 60F-254 as the stationary phase and the mobile phase consisted of n-propanol-methanol-concentrated ammonia solution (25%) (5:1:0.9, v/v/v). This solvent system was found to give compact spots for gatifloxacin (R(f) value of 0.60+/-0.02). Densitometric analysis of gatifloxacin was carried out in the absorbance mode at 292 nm. The linear regression analysis data for the calibration plots showed good linear relationship with r=0.9953 with respect to peak area in the concentration range of 400-1200 ng spot(-1). The mean value (+/-S.D.) of slope and intercept were 9.66+/-0.05 and 956.33+/-27.67, respectively. The method was validated for precision, accuracy, ruggedness and recovery. The limits of detection and quantitation were 2.73 and 8.27 ng spot(-1), respectively. Gatifloxacin was subjected to acid and alkali hydrolysis, oxidation, photodegradation and dry heat treatment. The drug undergoes degradation under acidic and basic conditions and upon wet and dry heat treatment. The degraded products were well separated from the pure drug. The statistical analysis proves that the developed method for quantification of gatifloxacin as bulk drug and from polymeric nanoparticles is reproducible and selective. As the method could effectively separate the drug from its degradation products, it can be employed as stability-indicating one.

Characterization of 5-fluorouracil microspheres for colonic delivery

The purpose of this investigation was to prepare and evaluate the colon-specific microspheres of 5-fluorouracil for the treatment of colon cancer. Core microspheres of alginate were prepared by the modified emulsification method in liquid paraffin and by cross-linking with calcium chloride. The core microspheres were coated with Eudragit S-100 by the solvent evaporation technique to prevent drug release in the stomach and small intestine. The microspheres were characterized by shape, size, surface morphology, size distribution, incorporation efficiency, and in vitro drug release studies. The outer surfaces of the core and coated microspheres, which were spherical in shape, were rough and smooth, respectively. The size of the core microspheres ranged from 22 to 55 microm, and the size of the coated microspheres ranged from 103 to 185 microm. The core microspheres sustained the drug release for 10 hours. The release studies of coated microspheres were performed in a pH progression medium mimicking the conditions of the gastrointestinal tract. Release was sustained for up to 20 hours in formulations with core microspheres to a Eudragit S-100 coat ratio of 1:7, and there were no changes in the size, shape, drug content, differential scanning calorimetry thermogram, and in vitro drug release after storage at 40 degrees C/75% relative humidity for 6 months.

Formulation and evaluation of once a day transdermal gels of diclofenac diethylamine

The present study was undertaken to prepare and evaluate transdermal gels of diclofenac diethylamine (DDEA) containing penetration enhancers such as olesan oil and dimethyl sulfoxide (DMSO). Transdermal gels were prepared using different polymers such as carbopol-940, polyvinyl alcohol (PVA), hydroxy propyl methyl cellulose-K(4) M, hydroxy propyl cellulose-M, and sodium carboxy methyl cellulose. The formulated gels were subjected to physicochemical studies, in vitro release studies and in vitro skin permeations studies and were evaluated for drug content, viscosity, extrudability, spreadability, and pH. The in vitro release studies of prepared gels were performed using specially designed Fites cell and in vitro skin permeation studies were performed using keshary-chien diffusion cell through rat skin. Selected formulations were evaluated for their antiinflammatory activity using the carrageenan-induced paw edema in rats. The carbopol-940 and PVA gels containing 10% DMSO showed best in vitro skin permeation of DDEA. In vivo study for the selected formulation showed a sustained reduction in inflammation in the carrageenan induced paw edema in rats. The efficacies of carbopol-940 and PVA gels were also compared with that of the marketed Voveran gel,(R) and it was found that carbopol and PVA gels produced better results than the Voveran gel. (c) 2006 Prous Science. All rights reserved.

Stability-indicating HPTLC determination of curcumin in bulk drug and pharmaceutical formulations

A simple, selective, precise and stability-indicating high-performance thin-layer chromatographic method of analysis of curcumin both as a bulk drug and in formulations was developed and validated. The method employed TLC aluminium plates precoated with silica gel 60 F-254 as the stationary phase. The solvent system consisted of chloroform:methanol (9.25:0.75 v/v). This system was found to give compact spots for curcumin (R(f) value of 0.48 +/- 0.02). Densitometric analysis of curcumin was carried out in the absorbance mode at 430 nm. The linear regression analysis data for the calibration plots showed good linear relationship with r = 0.996 and 0.994 with respect to peak height and peak area, respectively, in the concentration range 50-300 ng per spot. The mean value +/- S.D. of slope and intercept were 1.08 +/- 0.01, 51.93 +/- 0.54 and 8.39 +/- 0.21, 311.55 +/ -3.23 with respect to peak height and area, respectively. The method was validated for precision, recovery and robustness. The limits of detection and quantitation were 8 and 25 ng per spot, respectively. Curcumin was subjected to acid and alkali hydrolysis, oxidation and photodegradation. The drug undergoes degradation under acidic, basic, light and oxidation conditions. This indicates that the drug is susceptible to acid, base hydrolysis, oxidation and photo oxidation. Statistical analysis proves that the method is repeatable, selective and accurate 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.

Molecular inclusion of rofecoxib with cyclodextrin: pharmacological properties in laboratory animals

Rofecoxib is practically insoluble in water and its prolonged use is associated with the incidence of side effects like gastrointestinal perforations, ulcerations and bleeding. Therefore, an attempt has been made to improve the aqueous solubility of the drug by making an inclusion complex using dimethyl-beta-cyclodextrin (DIMEB). The complexes were prepared by kneading and by the spray drying method. The prepared complexes showed better anti-inflammatory activity and decreased ulcerogenic potential than the pure drug.