Cetin Tas

In vitro release studies of chlorpheniramine maleate from gels prepared by different cellulose derivatives

The objective of this study was to evaluate the in vitro and ex vivo percutaneous absorption of chlorpheniramine maleate (CPM) from different hydrogel formulations. Various concentrations of polymers, including hydroxypropylmethylcellulose (HPMC), sodium carboxymethylcellulose (NaCMC) and methyl cellulose (MC) were used in the hydrogel formulations. All experiments were conducted using cellulose dialysis membrane. The passive permeation of CPM was affected by the polymer concentrations. The effect of each polymer on the release rate of CPM was found to be statistically different (P<0.05). The formulation which exhibited maximum drug release through cellulose membrane was then used with other membranes namely polyurethane membrane, rat skin and human skin. The release rate of CPM from different membranes was found to be statistically different (P<0.05). Within the different diffusional barriers rat skin was found to be best alternative to human skin. It seems suitable the use of cellulose derivatives for topical application of CPM to obtain high therapeutic concentration at the application site. The synthetic membranes can be used to assess product performance in quality assurance but give little indication of its performance ex vivo.

Formulation of zolmitriptan sublingual tablets prepared by direct compression with different polymers: In vitro and in vivo evaluation

First-pass metabolism can be overcome by sublingual drug delivery, and quick drug entry into the systemic circulation can be obtained. In certain diseases such as migraine therapy, taking fast pharmacological response is an important criteria. In this study, zolmitriptan sublingual tablets were prepared by direct compression method using different mucoadhesive polymers such as hydroxypropyl methyl cellulose, chitosan and sodium carboxy methyl cellulose at a concentration range of 0.5-5% to reduce flushing action of saliva and provide enough time for drug to be absorbed. Tablets were evaluated for the physical properties, and optimum formulations were chosen for in vivo studies to carry on sheep model. The tablets disintegrated rapidly, and dissolution tests revealed that zolmitriptan was dissolved from the formulation within the compendial limits. This especially showed us that the concentration range of polymers is in acceptable limit. It was also concluded that microcrystalline cellulose, spray-dried lactose and sodium starch glycolate are the appropriate excipient and formulated in good proportions. In vivo studies indicated that formulation containing 5% chitosan has the maximum C(max) and AUC and minimum t(max) values (p<0.05). As a result, sublingual tablet administration of zolmitriptan formulated with appropriate excipients and especially with chitosan seems promising alternative to traditional routes.

In Vitro and Ex Vivo Permeation Studies of Etodolac from Hydrophilic Gels and Effect of Terpenes as Enhancers

Etodolac, a highly lipophilic anti-inflammatory drug, is widely used in rheumatoid arthritis usually at an oral dose of 200 mg twice daily. The commonest side effects during therapy with etodolac is generally gastrointestinal disturbances these are usually mild and reversible but in some patients are peptic ulcer and severe gastrointestinal bleeding. To eliminate these side effects and obtain high drug concentration at the application side, dermal application of etodolac seems to be an ideal route for administration. Hydrophilic gel formulations of etodolac were prepared with carboxymethylcellulose sodium. The effect of different terpenes (anethole, carvacrol, and menthol) as an enhancer on the percutaneous absorption of etodolac was also investigated. Permeation studies were carried out with unjacketed modified horizontal diffusion cells through cellulose membrane and rat skin. In vitro studies with cellulose membrane showed that all formulations presented the same drug release profile (p > 0.05). Ex vivo studies with excised rat skin revealed that etodolac was released and penetrated into rat skin quickly. Anethole, a hydrophobic terpene, enhanced the absorption of etodolac significantly (p < 0.05). This result is consistent with the fact that hydrophobic terpenes are effective on the percutaneous absorption of lipophilic drugs. Menthol and carvacrol, hydrophilic terpenes, did not enhance the absorption of etodolac. The lipophilicity of the enhancers seems an important factor in promoting penetration of etodolac through the skin. Since etodolac creates gastrointestinal disturbances, topical formulations of etodolac in gel form including 1% anethole could be an alternative.

Nasal administration of metoclopramide from different dosage forms: in vitro, ex vivo, and in vivo evaluation

Nasal drug delivery is an interesting route of administration for metoclopramide hydrochloride (MTC) in preventing different kind of emesis. Currently, the routes of administration of antiemetics are oral or intravenous, although patient compliance is often impaired by the difficulties associated with acute emesis or invasiveness of parenteral administration. In this perspective, nasal dosage forms (solution, gel, and lyophilized powder) of MTC were prepared by using a mucoadhesive polymer sodium carboxymethylcellulose (NaCMC). In vitro and ex vivo drug release studies were performed in a modified horizontal diffusion chamber with cellulose membrane and excised cattle nasal mucosa as diffusion barriers. The tolerance of nasal mucosa to the formulation and its components were investigated using light microscopy. In vivo studies were carried out for the optimized formulations in sheep and the pharmacokinetics parameters were compared with oral solution and IV dosage form. The release of MTC from solution and powder formulations was found to be higher than gel formulation (p < 0.05). Histopathological examination did not detect any severe damage. Hydroxypropyl-β-cyclodextrin (HPβCD) used in powder formulations was found to be effective for enhancing the release and absorption of MTC. In contrast to in vitro and ex vivo experiments nasal bioavailability of gel is higher than those of solution and powder (p < 0.05). In conclusion, the NaCMC gel formulation of MTC with mucoadhesive properties with increased permeation rate is promising for prolonging nasal residence time and thereby nasal absorption.

Drug Dissolution Studies and Determination of Deflazacort in Pharmaceutical Formulations and Human Serum Samples by RP‐HPLC

Abstract A simple, sensitive, reproducible, and validated RP‐HPLC method with UV detection is described for the determination of deflazacort in raw material, pharmaceuticals, human serum samples, and in‐vitro drug dissolution studies. The separation was achieved using a C18 (250 × 4.6 mm; 5 µm) column and a mobile phase comprising acetonitrile, methanol, and 0.067 M KH2PO4 in the ratio (27:20:53, v/v/v), adjusted to pH 6.5 with 3 M NaOH. The results of analysis were treated statistically and it has been validated and proven to be rugged. The limit of detection and limit of quantification were found as 2.05 ng mL−1 and 6.83 ng mL−1 in mobile phase and 4.06 ng mL−1 and 13.55 ng mL−1 in human serum samples, respectively. The method produced linear response in the concentration ranges 10–30,000 ng mL−1 in mobile phase and 25–30,000 ng mL−1 in serum samples. The intra‐ and inter‐day assay precision of the method was within 0.92% relative standard deviations in mobile phase and 1.48% relative standard deviations in human serum samples. This method was successfully applied for the determination of the drug in tablet dosage form, human serum, and drug dissolution studies. The results were found to be accurate, reproducible, and free from interference from the excipients or endogenous substance. #Presented at 3rd Agean Analytical Chemistry Days, September 29–October 3, 2002, Levos, Greece.

Effect of different polymers and their combinations on the release of metoclopramide HCl from sustained-release hydrophilic matrix tablets

Metoclopramide HCl (MTC) is commonly used for the management of gastrointestinal disorders. It has a short biological half-life and is usually administered four times daily to maintain effective concentrations throughout the day. The aim of this study is to develop sustained-release hydrophilic matrix tablet formulations of drug to achieve reproducible and predictable release rates, extended duration of activity, decreased toxicity, reduction of required dose, optimized therapy, and improved patient compliance. Hydroxypropylmethyl cellulose (HPMC), carboxymethylcellulose sodium (NaCMC), chitosan and Carbopol 981 were incorporated in the matrix system separately or in combinations as release controlling factor by direct compression technique. Compatibility among the formulation components was assessed by DSC and FTIR analysis. MTC release from matrix was evaluated by using the US Pharmacopeia dissolution apparatus II. All formulations met the criteria of pharmacopeial requirements. Dissolution studies show that polymer type and concentration are important parameters on drug release. Chitosan, carbopol and NaCMC formulations exhibited pH-dependent drug release profile whereas HPMC did not. All the formulations containing 1:1 ratio of HPMC and chitosan exhibited desired drug release showing that all active substance releases progressively in a period of whole dissolution time and therefore it can be regarded as worthy of consideration for the manufacture of sustained-release MTC product.

The Development and In Vitro Evaluation of Sustained Release Tablet Formulations of Benzydamine Hydrochloride and its Determination

A novel oral controlled delivery system for benzydamine hydrochloride (BN) was developed and optimized. Hydrophilic matrix tablets of BN were prepared by using hydroxypropylmethylcellulose (HPMC) and chitosan as polymer substance to achieve required sustained release profile. The matrix tablets were prepared both direct compression and wet granulation method. The influence of matrix forming agents and binary mixtures of them on BN release was investigated. The formulated tablets were characterized by hardness, friability, thickness, weight variation and in vitro drug release. The formulated tablets had acceptable physicochemical characters. The quantity of BN present in the tablets and the release medium were estimated by a simple, sensitive, rapid and validated HPLC method. The dissolution results show that increased amount of polymer resulted in reduced and extended drug release. F7 formulation containing 12.5% HPMC and 12.5 % chitosan with direct compression method is the optimum formulation due to its better targeting profile in terms of release. Higuchi (diffusion) and Hixon-Crowell (erosion) kinetic profiles were achieved and this codependent mechanism of drug release was established. This formulation may provide an alternative for oral controlled delivery of BN and be helpful in the future treatment of primary normoreactive types of inflammation.

RP‐HPLC Assay of Rofecoxib from Pharmaceutical Dosage Forms and Human Plasma and Its Drug Dissolution Studies

ABSTRACT A high performance liquid chromatographic (HPLC) method is described for the determination of rofecoxib (RFC) in bulk drug, tablets, and human plasma samples. The methods are linear over the concentration ranges 0.005–30.0 and 0.010–10 µg mL−1 in mobile phase and human plasma, respectively. Chromatography was carried out on a reversed phase Spherisorb ODSI column using a mixture of acetonitrile:methanol: 0.067 M KH2PO4 (27:20:53, v/v/v) adjusted to pH 6.95 with 3 M NaOH. Detection was realized at 244 nm using a DAD detector. The retention time observed for RFC and etodolac (internal standard) at about 7.5 and 10.7 min, respectively. The proposed RP‐HPLC method was validated for precision, accuracy, ruggedness, and recovery. The limit of detection was found to be 0.00143 and 0.00301 µg mL−1 in mobile phase and human plasma samples, respectively. The proposed method allows a number of cost and time saving benefits. The described method can be readily applied for the analysis of tablets, drug dissolution studies, and human plasma samples. This method could be used without any interference from tablet matrix and endogenous substance from the plasma samples.

Sutureless microvascular anastomosis with the aid of heparin loaded poloxamer 407

BACKGROUND Anastomosis with tissue adhesives is an alternative method for conventional anastomosis. However, this method has several technical challenges. It requires the use of suture to prevent leakage into lumen and precise application onto all surfaces of the anastomosis site. To solve these problems, poloxamer 407 (P 407) was previously used as a stent. In this study, we made heparinized P 407 (h-P 407) as a new formula. We aimed to successfully use h-P 407 as a stent in sutureless anastomosis in a rat abdominal aorta model. METHODS Sixty Sprague-Dawley rats were used. In the first group, end-to-end anastomoses were performed with suture; in the second and third groups, sutureless anastomoses were performed with 2-octyl cyanoacrylate. As an intraluminal stent, P 407 was used in the second group, and h-P 407 was used in the third group. Anastomosis time was measured. Lumen width, intimal hyperplasia, and foreign body reaction were assessed histologically. Velocity flow rates and vessel diameters were measured radiologically. Burst strength was measured, and the results were statistically evaluated. RESULTS Sutureless anastomosis was more rapid than conventional anastomosis. Lumen width was narrower in the suture group. İnflammation and foreign body reaction were more severe in the suture group. There was no radiologic and biomechanical difference between the groups. We found that intimal hyperplasia was less in h-P 407 than in P 407. CONCLUSION h-P407 can be successfully used as an intraluminal stent for sutureless microvascular anastomosis with tissue adhesives.