Penetration-enhancing effect of ethanolic solution of menthol on transdermal permeation of ondansetron hydrochloride across rat epidermis.

The aim of this investigation was to study the effect of an ethanol-water solvent system and ehtanolic solution of menthol on the permeation of ondansetron hydrochloride across the rat epidermis in order to select a suitable ethanol-water vehicle and optimal concentration of menthol for the development of a transdermal therapeutic system. The solubility of ondansetron hydrochloride in ethanol, water and selected concenetrtaion of ethanol-water vehicles (20:80 v/v, 40:60 v/v and 60:40 v/v) was determined. The effect of these solvent vehicles, containing 1.5% w/v of ondansetron hydrochloride, on the in vitro permeation of the drug was studied across the rat epidermis. The highest permeation was observed from 60% v/v of ethanol-water vehicle that showed highest solubilty. Hence, the hydroxypropyl cellulose (HPC) (2% w/w) gel formulations containing 1.5% w/w of ondansetron hydrochloride and selected concentrations of menthol (0, 2, 4, 8 and 10% w/w) were prepared using 60% v/v of ethanol-water vehicle, and subjected to in vitro permeation of the drug across rat epidermis. The transdermal permeation of ondansetron hydrochloride was enhanced markedly by the addition of menthol to HPC gel drug reservoir formulations. A maximum flux of ondansetron hydrochloride (77.85 +/- 2.85 mu g/cm(2.)h) was observed with a mean enhancement ratio of 13.06 when menthol was incorporated at a concentration of 8% w/w in HPC gels. However, there was no significant increase in the drug flux with 10% w/w menthol when compared to that obtained with 8% w/w of menthol in HPC gel formulations. The results suggest that 2% w/w HPC gel drug reservoir formulation, prepared with 60% v/v ethanol-water, containing 8% w/w of menthol provides an optimal transdermal permeation of ondansetron hydrochloride.

Effect of nerodilol, carvone and anethole on the in vitro transdermal delivery of selegiline hydrochloride.

The aim of the study was to investigate the effect of terpene enhancers (nerodilol, carvone or anethole) on the in vitro transdermal delivery of selegiline hydrochloride with a broad objective of developing a membrane-moderated transdermal therapeutic system (TTS). The in vitro permeation studies were carried across the rat epidermis from hydroxypropyl methylcellulose (HPMC) gel drug reservoir containing selected concentrations of nerodilol, carvone or anethole and selegiline hydrochloride. The amount of selegiline hydrochloride permeated during the 24 h of the study (Q24) from HPMC gel drug reservoir without terpene enhancer was 2169 +/- 50 microg/cm2 and the corresponding flux of the drug was 92 +/- 1 microg/cm2 x h. The amount of drug permeated and its flux increased with an increase in terpne concentration in HPMC gel drug reservoir. Nerodilol provided an approximately 3.2-fold increase in the flux of selegiline hydrochloride followed by carvone with a 2.8-fold increase, and anethole with a 2.6-fold increase. It is concluded that the terpene nerodilol, carvone and anethole produced a marked penetration enhancing effect on the in vitro transdermal delivery of selegiline hydrochloride that could possibly be used in the formulation of membrane-moderated TTS.

Controlled in vivo release of nicorandil from a carvone-based transdermal therapeutic system in human volunteers.

The aim of our present study was to prepare and evaluate a carvone-based transdermal therapeutic system (TTS) of nicorandil to find its ability in providing the desired in vivo controlled release profile on dermal application to human volunteers. The effect of EVA 2825, and adhesive-coated EVA 2825, and adhesive-coated EVA 2825-rat skin composite on the in vitro permeation of nicorandil from a carvone-based HPMC gel drug reservoir was studied against a control (rat abdominal skin alone). The carvone-based drug reservoir system was sandwiched between adhesive-coated EVA 2825-release liner composite and a backing membrane. The resultant drug reservoir sandwich was heat-sealed to produce a circle-shaped TTS (20 cm(2)) that was subjected to in vivo evaluation on dermal application to human volunteers against oral administration of immediate-release tablets of nicorandil. The carvone-based TTS provided a steady-state plasma concentration of 20.5 ng/ml for approximately 24 hr in human volunteers. We concluded that the carvone-based TTS of nicorandil provided the desired in vivo controlled-release profile of the drug for the predetermined period of time.

In vitro and in vivo evaluation of guar gum-based matrix tablets of rofecoxib for colonic drug delivery.

The present study was carried out to develop and evaluate guar gum-based matrix tablets of rofecoxib for their intended use in the chemoprevention of colorectal cancer. Matrix tablets containing 40% (RXL-40), 50% (RXL-50), 60% (RXL-60) or 70% (RXL-70) of guar gum were prepared by wet granulation technique, and were subjected to in vitro drug release studies. Guar gum matrix tablets released only 5 to 12% of rofecoxib in the physiological environment of stomach and small intestine. The matrix tablets RXL-40 disintegrated completely within 10 h in a dissolution medium without rat caecal contents (control study), and hence not studied further. When the dissolution study was continued in simulated colonic fluids (rat caecal content medium), the matrix tablets RXL-50 were acted upon by colonic bacterial enzymes releasing the entire quantity of drug wherein there was no appreciable difference when compared to that released in control study. The matrix tablets RXL-60 released another 88% of rofecoxib whereas matrix tablets RXL-70 released only 57% of rofecoxib in simulated colonic fluids indicating the susceptibility of the guar gum formulations to the rat caecal contents. The guar gum matrix tablets RXL-70 were subjected to in vivo evaluation in human volunteers to find their ability of targeting rofecoxib to colon. The delayed Tmax, prolonged absorption time (ta), decreased Cmax and decreased ka indicated that rofecoxib was not released significantly in stomach and small intestine, but was delivered to colon resulting in a slow absorption of the drug and making it available for local action in human colon.

In vivo evaluation of limonene-based transdermal therapeutic system of nicorandil in healthy human volunteers.

Hydroxypropyl methylcellulose (HPMC) gel drug reservoir system prepared with 70:30 v/v ethanol-water solvent system containing 6% w/w of limonene was effective in promoting the in vitro transdermal delivery of nicorandil. The objective of the present study was to fabricate and evaluate a limonene-based transdermal therapeutic system (TTS) for its ability to provide the desired steady-state plasma concentration of nicorandil in human volunteers. The in vitro permeation of nicorandil from a limonene-based HPMC gel drug reservoir was studied across excised rat skin (control), EVA2825 membrane, adhesive-coated EVA2825 membrane and adhesive-coated EVA2825 membrane-excised rat skin composite to account for their effect on the desired flux of nicorandil. The flux of nicorandil from the limonene-based HMPC drug reservoir across EVA2825 membrane decreased to 215.8 +/- 9.7 microg/cm(2).h when compared to that obtained from control, indicating that EVA2825 was effective as a rate-controlling membrane. The further decrease in nicorandil flux across adhesive-coated EVA2825 membrane and adhesive-coated EVA2825 membrane-excised rat skin composite showed that the adhesive coat and skin also controlled the in vitro transdermal delivery. The limonene-based drug reservoir was sandwiched between adhesive-coated EVA2825-release liner composite and a backing membrane. The resultant sandwich was heat-sealed as circle-shaped patch (20 cm(2)), trimmed and subjected to in vivo evaluation in human volunteers against immediate-release tablets of nicorandil (reference formulation). The fabricated limonene-based TTS of nicorandil provided a steady-state plasma concentration of 21.3 ng/ml up to 24 h in healthy human volunteers. It was concluded that the limonene-based TTS of nicorandil provided the desired plasma concentration of the drug for the predetermined period of time with minimal fluctuations and improved bioavailability.

Bioavailability of nerodilol-based transdermal therapeutic system of nicorandil in human volunteers.

The objective of the present investigation was to design and evaluate a nerodilol-based transdermal therapeutic system (TTS) for finding its ability in providing the desired steady-state plasma concentration of nicorandil in human volunteers. The influence of EVA2825 membrane, adhesive-coated EVA2825 membrane and adhesive-coated EVA2825-rat skin composite on the in vitro permeation of nicorandil from a nerodilol-based HPMC gel drug reservoir was studied against a control (excised rat skin alone). The flux of nicorandil from the nerodilol-based HMPC drug reservoir across excised rat skin (control) was 384.0+/-4.6 microg/cm2 h and this decreased to 222.7+/-7.1 microg/cm2 h when studied across EVA2825 membrane indicating that EVA2825 membrane was effective as rate controlling membrane. The flux of the drug decreased to 183.8+/-5.7 microg/cm2 h on application of a water-based acrylic adhesive (TACKWHITE A 4MED) coat to EVA2825 membrane. However, the flux of nicorandil across adhesive-coated EVA2825-membrane-rat-skin composite was 164.8+/-1.8 microg/cm2 h, which was 1.74-times of the required flux that prompted for preparation of TTS. The nerodilol-based drug reservoir system was sandwiched between a composite of adhesive-coated EVA2825 membrane-release liner and a backing membrane. The resultant sandwich was heat-sealed to produce circle-shaped TTS (20 cm2) that were subjected to bioavailability study in human volunteers against immediate release nicorandil tablet. The nerodilol-based TTS provided a steady-state plasma concentration of 25.5 ng/ml for 24 h in human volunteers. It was concluded that the nerodilol-based TTS of nicorandil provided the desired plasma concentration of the drug for the predetermined period of time with minimal fluctuations.

Formulation of an HPMC gel drug reservoir system with ethanol-water as a solvent system and limonene as a penetration enhancer for enhancing in vitro transdermal delivery of nicorandil.

The objective of the present study was to formulate a hydroxypropyl methylcellulose (HPMC) gel drug reservoir system with ethanol-water as a solvent system and limonene as a penetration enhancer for enhancing the transdermal delivery of nicorandil so as to develop and fabricate a membrane-moderated transdermal therapeutic system (TTS). The in vitro permeation of nicorandil was determined across rat abdominal skin from a solvent system consisting of ethanol or various proportions of ethanol and water. The ethanol-water (70:30 v/v) solvent system that provided an optimal transdermal permeation was used in formulating an HPMC gel drug reservoir system with selected concentrations (0% w/w, 4% w/w, 6% w/w, 8% w/w or 10% w/w) of limonene as a penetration enhancer for further enhancement of transdermal permeation of nicorandil. The amount of nicorandil permeated in 24 h was found increased with an increase in the concentration of limonene in the drug reservoir system up to a concentration of 6% w/w, but beyond this concentration there was no further increase in the amount of drug permeated. The flux of nicorandil was 370.9 +/- 4.2 microg/cm2 x h from the drug reservoir system with 6% w/w of limonene, which is about 2.6 times the required flux to be obtained across rat abdominal skin for producing the desired plasma concentration for the predetermined period in humans. The results of a Fourier Transform Infrared study indicated that limonene enhanced the percutaneous permeation of nicorandil by partially extracting the stratum corneum lipids. It is concluded that the HPMC gel drug reservoir system prepared with a 70:30 v/v ethanol-water solvent system containing 6% w/w of limonene is useful in designing and fabricating a membrane-moderated TTS of nicorandil.

Pharmacokinetic evaluation of guar gum-based three-layer matrix tablets for oral controlled delivery of highly soluble metoprolol tartrate as a model drug.

The objective of the present study is to carry out pharmacokinetic evaluation of oral controlled release formulation (guar gum-based three-layer matrix tablets) containing highly soluble metoprolol tartrate as a model drug. Six healthy volunteers participated in the study, and a two-way crossover design was followed. The plasma concentration of metoprolol tartrate was estimated by reverse-phase HPLC. The pharmacokinetic parameters were calculated from the plasma concentration of metoprolol tartrate versus time data. The delayed T(max) lower C(max) decreased K(a) unaltered bioavailability and prolonged t(1/2) indicated a slow and prolonged release of metoprolol tartrate from guar gum three-layer matrix tablets in comparison with the immediate release tablet dosage form. The results of the study indicated that guar gum three-layer matrix tablets were able to provide oral controlled delivery of highly water-soluble drug such as metoprolol tartrate in humans.

Formulation and evaluation of limonene-based membrane-moderated transdermal therapeutic system of nimodipine.

The aim of the present study was to design a membrane-moderated transdermal therapeutic system (TTS) of nimodipine using 2% w/w hydroxypropyl methylcellulose (HPMC) gel as a reservoir system containing 4% w/w of limonene as a penetration enhancer. The permeability flux of nimodipine through ethylene vinyl acetate (EVA) copolymer membrane was found to increase with an increase in vinyl acetate content in the copolymer (9 to 28%). The effect of pressure-sensitive adhesives such as TACKITE A 4MED on the permeability of nimodipine through EVA membrane 2825 (28% w/w vinyl acetate) or membrane/rat skin composite also was studied. The permeability flux of nimodipine from the chosen EVA 2825 (with 28% vinyl acetate content) was 159.72 +/- 1.96 microg/cm2/hr, and this flux further decreased to 141.85 +/- 1.54 microg/cm2/hr on application of pressure-sensitive adhesive (TACKWHITE A 4MED). However, the transdermal permeability flux of nimodipine across EVA 2825 membrane coated with TACKWHITE A 4MED/rat skin composite was found to be 126.59 +/- 2.72 microg/cm2/hr, which is 1.3-fold greater than the required flux. Thus, a new transdermal therapeutic system for nimodipine was formulated using EVA 2825 membrane coated with a pressure-sensitive adhesive TACKWHITE 4A MED and 2% w/w HPMC gel as reservoir containing 4% w/w of limonene as a penetration enhancer. The bioavailability studies in healthy human volunteers indicated that the TTS of nimodipine, designed in the present study, provided steady-state plasma concentration of the drug with minimal fluctuations for 20 hr with improved bioavailability in comparison with the immediate release tablet dosage form.

Penetration-enhancing effect of ethanol-water solvent system and ethanolic solution of carvone on transdermal permeability of nimodipine from HPMC gel across rat abdominal skin.

The aim of this investigation was to find the effect of the ethanol-water solvent system and the ethanolic solution of carvone on the permeation of nimodipine across rat abdominal skin in order to select a suitable solvent system and optimal concentration of carvone for the development of membrane-moderated transdermal therapeutic system of nimodipine. The solubility of nimodipine in water, ethanol, and ethanol-water cosolvent systems, or the selected concentration of carvone [2% (w/w) to 12% (w/w)] in 60:40 (v/v) ethanol-water were determined. The effect of these solvents or cosolvent systems on the transdermal permeation of nimodipine was also studied using in vitro permeability studies across the rat abdominal skin. The co-solvent system containing 60:40 (v/v) of ethanol-water showed highest permeability across the rat abdominal skin. Further, the effect of ethanolic solution [60% (v/v) ethanol-water] of carvone [2% (w/w) to 12% (w/w)] on the in vitro permeation of nimodipine across the rat abdominal skin from 2% (w/w) hydroxypropyl methylcellulose (HPMC) gel was also investigated. The transdermal permeability of nimodipine across rat abdominal skin was enhanced further by the addition of carvone to HPMC gel prepared with 60% (v/v) of ethanol. There was a steady effect on the flux of nimodipine (161.02 +/- 4.14 microg/cm2/hr) with an enhancement ratio of 4.56 when carvone was incorporated at a concentration of 10% (w/w) in HPMC gels prepared with 60% (v/v) ethanol. The Fourier transform infrared data indicated that ethanolic solution of carvone increased the transdermal permeability of nimodipine across the rat abdominal skin by partial extraction of lipids in the stratum corneum. The results suggest that 10% (w/w) of carvone in 60% (v/v) ethanol-water, along with HPMC as antinucleating agent may be useful for enhancing the skin permeability of nimodipine from the membrane-moderated transdermal therapeutic system.

Studies on the transdermal delivery of nimodipine from a menthol-based TTS in human volunteers.

The purpose of the present study was to design a membrane-moderated transdermal therapeutic system (TTS) of nimodipine using 2%w/w hydroxypropyl methylcellulose (HPMC) gel as a reservoir system containing menthol as penetration enhancer and 60%v/v ethanol-water as solvent system. The flux of nimodipine was markedly increased from 35.51 microg/cm2/h to 167.53+/-3.69 microg/cm2/h with the addition of 8%w/w menthol to HPMC drug reservoir. There was an increase in the flux of nimodipine through ethylene vinyl acetate (EVA) copolymer membrane with an increase in vinyl acetate content (9 to 28%w/w) of the copolymer. The permeability flux of nimodipine from the chosen EVA 2825 (with 28%w/w vinyl acetate content) was 152.05+/-2.68 microg/cm2/h, and this flux decreased to 132.69+/-1.45 microg/cm2/h on application of a water-based acrylic adhesive (TACKWHITE A 4MED) coat. However, the transdermal flux of nimodipine across EVA 2825 membrane coated with TACKWHITE A 4MED/ rat skin composite was found to be 116.05+/-2.39 microg/cm2/h, which is about 1.4 times greater than the required flux. Thus a new transdermal therapeutic system for nimodipine was designed using EVA 2825 membrane coated with a pressure-sensitive adhesive TACKWHITE 4A MED, and 2%w/w HPMC gel as reservoir containing 8%w/w of menthol as a penetration enhancer. The in vivo evaluation of nimodipine TTS patch was carried out to find the ability of the fabricated menthol-based TTS patch in providing the predetermined plasma concentration of the drug in human volunteers. The results showed that the menthol-based TTS patch of nimodipine provided steady plasma concentration of the drug with minimal fluctuations with improved bioavailability in comparison with the immediate release tablet dosage form.

In vitro percutaneous permeability enhancement of nimodipine by limonene across the excised rat abdominal skin.

The purpose of the present study was to investigate the effect of limonene on the in vitro permeation of nimodipine across the excised rat abdominal skin from a 2% w/w hydroxypropyl methylcellulose (HPMC) gel drug reservoir system. The HPMC gel formulations containing 1.5% w/w of nimodipine and selected concentrations of limonene (0% w/w to 8% w/w) were prepared, and subjected to in vitro permeation of the drug through excised rat abdominal epidermis. The drug content in the gels was found to be uniform, and the drug was found to be stable in HPMC gel formulations. The flux of nimodipine across rat epidermis was markedly increased by the addition of limonene to the HPMC gels. A maximum flux of nimodipine was observed (203+/-0.6 microg/cm2 x h) with an enhancement ratio of about 5.7 when limonene was incorporated in HPMC gel at a concentration of 4% w/w. However, there was no further increase in the permeability of nimodipine beyond 4% w/w of limonene in the HPMC gel. FT-IR data indicated that limonene increased the permeability of nimodipine across the rat epidermis by partial extraction of lipids in the stratum corneum. The results suggest that limonene is useful for enhancing the skin permeability of nimodipine from transdermal therapeutic systems containing HPMC gel as a reservoir.

Pharmacokinetic evaluation of guar gum-based colon-targeted drug delivery systems of tinidazole in healthy human volunteers.

The aim of the present investigation was to determine the in vivo availability of guar gum-based colon-targeted tablets of tinidazole in comparison with immediate release tablets of tinidazole in human volunteers. Six healthy volunteers participated in the study, and a cross-over design was used. The plasma concentration of tinidazole was estimated by HPLC. The pharmacokinetic parameters were calculated from the plasma concentration of tinidazole versus time data. The immediate release tablets of tinidazole produced a peak plasma concentration (Cmax of 3239 +/- 428 ng/ml) at 1.04 +/- 0.32 hr (Tmax), whereas colon-targeted tablets produced peak plasma concentration (Cmax of 2158 +/- 78 ng/ml) at 14.9 +/- 1.6 hr. The delayed Tmax, decreased Cmax, and Ka, and unaltered bioavailability and elimination half-life of tinidazole from guar gum-based colon-targeted tinidazole tablets, in comparison with the immediate tablets, indicated that the drug was not released in the stomach and small intestine but delivered to the colon. Slow absorption of the drug from the less absorptive colon might result in the availability of the drug for local action in the colon. The guar gum-based colon-targeted tablets of tinidazole may be useful in providing an effective and safe therapy of intestinal amoebiasis.

Effect of carvone on the permeation of nimodipine from a membrane-moderated transdermal therapeutic system.

The purpose of this investigation was to develop a membrane-moderated transdermal therapeutic system (TTS) of nimodipine using 2% w/w hydroxypropylmethylcellulose (HPMC) gel as a reservoir system containing 10% w/w of carvone (penetration enhancer) in 60% v/v ethanol. The flux of nimodipine through an ethylene vinyl acetate (EVA) copolymer membrane was found to increase with an increase in vinyl acetate content in the copolymer. The effect of a pressure-sensitive adhesive (TACKWHITE A 4MED) on the permeability of nimodipine through an EVA 2825 membrane (28% w/w vinyl acetate) or an EVA 2825 membrane/skin composite was also studied. An EVA 2825 membrane coated with TACKWHITE 4A MED was found to provide the required flux of nimodipine (117 +/- 5 microg/cm2/h) across rat abdominal skin. Thus a new transdermal therapeutic system for nimodipine was formulated using EVA 2825 membrane, coated with a pressure-sensitive adhesive TACKWHITE 4A MED, and 2% w/w HPMC gel as reservoir containing 10% w/w of carvone as a penetration enhancer. Studies in healthy human volunteers indicated that the TTS of nimodipine, designed in the present study, provided steady-state plasma concentration of the drug with minimal fluctuations.

In vivo pharmacokinetics in human volunteers: oral administered guar gum-based colon-targeted 5-fluorouracil tablets.

The objective of the present study is to compare the guar gum-based colon-targeted tablets of 5-fluorouracil against an immediate release tablet by in vitro dissolution and in vivo pharmacokinetic studies in human volunteers. Twelve healthy volunteers participated in the study. 5-Fluorouracil was administered at a dose of 50 mg both in immediate release tablet and colon-targeted tablet. On oral administration of colon-targeted tablets, 5-fluorouracil started appearing in the plasma at 6 h, and reached the peak concentration (C(max) of 216+/-15 ng/ml) at 7.6+/-0.1 h (T(max)), whereas the immediate release tablets produced peak plasma concentration (C(max) of 278+/-21 ng/ml) at 0.6+/-0.01 h (T(max)). The AUC(0- infinity ) for 5-fluorouracil from colon-targeted tablet and immediate release tablet were found to be 617+/-39 and 205+/-21 ng/ml/h, respectively. Colon-targeted tablets showed delayed t(max), delayed absorption time (t(a)), decreased C(max) and decreased absorption rate constant when compared to the immediate release tablets. The results of the study indicated that the guar gum-based colon-targeted formulation did not release the drug in stomach and small intestine, but delivered it to the colon resulting in a slow absorption of the drug and making it available for local action in colon.

In vivo evaluation of guar gum-based colon-targeted drug delivery systems of ornidazole in healthy human volunteers.

The aim of the present study was to find the in vivo performance of guar gum-based colon-targeted tablets of ornidazole (dose 250 mg) in comparison with an immediate release tablet of ornidazole (250 mg) in human volunteers. Six healthy volunteers participated in the study, and a cross over design was followed. The plasma concentration of ornidazole was estimated by HPLC. The immediate release tablets of ornidazole produced peak plasma concentration (Cmax of 2171.33+/-278.15 ng/ml) at 2.91+/-0.14 h (Tmax) whereas colon-targeted tablets produced peak plasma concentration (Cmax of 1716.66+/-125.83 ng/ml) at 11.91+/-0.14 h. The delayed Tmax, decreased Cmax, and decreased ka of ornidazole from guar gum-based colon-targeted ornidazole tablets, in comparison with the immediate tablets, indicated that the drug was not released in stomach and small intestine, but targeted to colon. Slow absorption of ornidazole from the less absorptive colon might result in the availability of drug for local action in the colon.

Influence of menthol and pressure-sensitive adhesives on the in vivo performance of membrane-moderated transdermal therapeutic system of nicardipine hydrochloride in human volunteers.

A membrane-moderated transdermal therapeutic system of nicardipine hydrochloride was developed using 2% w/w hydroxypropylcellulose (HPC) gel as a reservoir system containing 5% w/w of menthol as a penetration enhancer. The permeability flux of nicardipine hydrochloride through the ethylene vinyl acetate (EVA) copolymer membrane was found to increase with an increase in vinyl acetate content in the copolymer. The effect of various pressure-sensitive adhesives (MA-31, MA-38 or TACKWHITE A 4MED on the permeability of nicardipine hydrochloride through EVA 2825 membrane (28% w/w vinyl acetate) or EVA 2825 membrane/skin composite was also studied. The results showed that nicardipine hydrochloride permeability through EVA 2825 membrane coated with TACKWHITE A 4MED/skin composite was higher than that coated with MA-31 or MA-38. Thus, a new transdermal therapeutic system for nicardipine hydrochloride was formulated using EVA 2825 membrane coated with a pressure-sensitive adhesive TACKWHITE A 4MED, and 2% w/w HPC gel as reservoir containing 5% w/w of menthol as a penetration enhancer. In vivo studies in healthy human volunteers indicated that the TTS of nicardipine hydrochloride, designed in the present study, provided steady-state plasma concentration of the drug with minimal fluctuations for 26h with improved bioavailability in comparison with the immediate release capsule dosage form.

Studies on the development of colon targeted oral drug delivery systems for ornidazole in the treatment of amoebiasis.

The aim of the present study is to develop colon-targeted drug delivery systems for ornidazole using guar gum as a carrier. The core formulation containing ornidazole was directly compressed. Compression-coated tablets of ornidazole containing various proportions of guar gum in the coat were prepared. All the formulations were evaluated for hardness and drug content uniformity and were subjected to in vitro drug release studies. The amount of ornidazole released from tablets at different time intervals was estimated by the HPLC method. The compression-coated formulations released less than 8% of ornidazole in the physiological environment of stomach and small intestine. The compression-coated tablets with 85%, 75%, and 65% of guar gum coat released about 21%, 38%, and 73% of ornidazole, respectively, in simulated colonic fluids indicating the susceptibility of the guar gum formulations to the rat caecal contents. The results of the study show that compression-coated ornidazole tablets with either 65% (OLV-65) or 75% (OLV-75) of guar gum coat are most likely to provide targeting of ornidazole for local action in the colon owing to its minimal release of the drug in the first 5 hr. The ornidazole compression-coated tablets showed no change in physical appearance, drug content, or in dissolution pattern after storage at 40 degrees C/75% relative humidity for 6 months.

Formulation and in vivo evaluation of membrane-moderated transdermal therapeutic systems of nicardipine hydrochloride using carvone as a penetration enhancer.

A membrane-moderated transdermal therapeutic system (TTS) of nicardipine hydrochloride was developed using 2%w/w hydroxy propyl cellulose (HPC) gel as a reservoir system containing 8%w/w of carvone as a penetration enhancer. The permeability flux of nicardipine hydrochloride through ethylene vinyl acetate (EVA) copolymer membrane was found to increase with an increase in vinyl acetate content in the copolymer. The effect of various pressure-sensitive adhesives (MA-31, MA-38, or TACKWHITE A 4MED) on the permeability of nicardipine hydrochloride through EVA 2825 membrane (28%w/w vinyl acetate) or EVA 2825 membrane/skin composite also was studied. The results showed that nicardipine hydrochloride permeability through EVA 2825 membrane coated with TACKWHITE A 4MED/skin composite was higher than that coated with MA-31 or MA-38. Thus, a new TTS for nicardipine hydrochloride was formulated using EVA 2825 membrane coated with a pressure-sensitive adhesive TACKWHITE A 4MED and 2%w/w HPC gel as reservoir containing 8%w/w of carvone as a penetration enhancer. The bioavailability studies in healthy human volunteers indicated that the TTS of nicardipine hydrochloride, designed in the present study, provided steady-state plasma concentration of the drug with minimal fluctuations for 23 hr with improved bioavailability in comparison with the immediate-release capsule dosage form.

Enhanced percutaneous permeability of nicardipine hydrochloride by carvone across the rat abdominal skin.

The purpose of this study was to investigate the effect of carvone on the permeation of nicardipine hydrochloride across the excised rat abdominal epidermis from 2% w/w hydroxypropyl cellulose (HPC) gel system. The HPC gel formulations containing nicardipine hydrochloride (1% w/w) and selected concentrations of carvone (0 to 12% w/w) were prepared, and evaluated for drug content, stability of the drug, and in vitro permeation of the drug through excised rat abdominal epidermis. The HPC gel was found to contain 99.98 to 101.6% of nicardipine hydrochloride, and the drug was found to be stable in the HPC gels. The permeation flux of nicardipine hydrochloride across rat epidermis was increased markedly by the addition of carvone to the HPC gels. A maximum flux of nicardipine hydrochloride (243.95.70 +/- 1.90 microg/cm2/hr) was observed with an enhancement ratio of 7.9 when carvone was incorporated at a concentration of 12% w/w in the HPC reservoir system. The differential scanning calorimetry and Fourier transform-infrared data indicated that carvone increased the permeability of nicardipine hydrochloride across the rat epidermis by partial extraction of lipids in the stratum corneum. The results suggest that carvone may be useful for enhancing the skin permeability of nicardipine hydrochloride from transdermal therapeutic system containing HPC gel as a reservoir.