Carvedilol

The present study aims at investigating the different combinations of polymers with inclusion complex of Carvedilol (CR)-Hydroxypropyl betacyclodextrin (HPβCD) prepared in a ratio of 1:1 by use of various analytical techniques like Fourier Transformation Infrared spectroscopy (FTIR), X-ray diffraction technique (XRD), Digital scanning calorimetry (DSC), Thermo gravimetric analysis (TGA) as a part of preformulation studies. Various polymers used for the present study were Sodium alginate (SA), Hydroxy propyl beta cyclodextrin (HPBCD), Hydroxy propyl methyl cellulose LV E-15(HPMC), Pectin (P), Eudragit NE30D (EU). This study indicated that Carvedilol formed inclusion complex with the HPβCD, but in combination with other polymers, drug did not show any other interactions.

Carvedilol is a non selective α and β receptor blocker which undergoes extensive hepatic first pass metabolism by liver and has poor oral bioavailability of 25% - 30%. In the present investigation Carvedilol was formulated as a bilayered buccal adhesive tablets in order to avoid the first-pass effect and decrease the drug loss using two different natural polymers and excipients. Six formulations were made using different concentrations (17%w/w, 35%w/w, 53%w/w) of Pectin and Guar gum. Formulation F5 was selected for further studies of permeability. Three concentrations of SLS (1%, 1.5% & 2%w/w) was used to study the effect of permeation enhancer and improve the permeability of drug. The formulations were tested for % weight variation, hardness, Friability, % Drug content, in-vitro drug release, surface pH, Swelling index and Mucoadhesive strength. Mucoadhesive strength was determined by the modified balance method in grams and was found to be between 23.75±0.332gm to 60.89±0.134gm and Surface pH was found to be 7. In-vitro release studies revealed that as polymer concentration increases from 17% to 53%w/w, rate of drug release was retarded and the data was fitted into pharmacokinetic models. Among all other formulations, formulations (F5) containing 35%w/w Guar gum were found to be best as the release was retarded upto 8 hours and they have good mucoadhesive strength and they follow zero order with non-fickian diffusion mechanism. Formulation F9 (2%w/w SLS) shows more permeability of drug (34%) compared to other formulations.

The study aim was concerned with formulation and in vitro evaluation of mucoadhesive buccal patch of carvedilol, which is extensively metabolized by liver. During last few years mucoadhesive dosage forms have promoted an area of drug delivery system that renders the treatment more effective and safe, not only for topical disorders but also for systemic problems. Therefore the present investigation is concerned with the development of the bucco-mucoadhesive patches, which were designed to prolong the buccal residence time, to increase penetration through buccal mucosa and thus increase the bioavailability. Various formulations were developed by using release rate controlling patches forming polymers like HPMC (K15, K4), HPC-L, Sodium alginate, PVP K30& Carbopol 934P in  alone & various combinations by solvent casting technique using plasticizer glycerol. For unidirectional release, backing layer prepared using ethyl cellulose 2.5%w/v dissolve in isopropyl alcohol and acetone. Glycerol used as a plasticizer was casted on the patches. The patches were evaluated for their thickness uniformity, folding endurance, weight uniformity, content uniformity, swelling behaviour, tensile strength, and surface pH, In vitro release studies, in vitro residence time, in vitro diffusion study. Patches exhibited drug release (diffusion) in the range of 75.69% to 96.53%. Kinetic models i.e. Higuchi, Korsemeyer-peppas, zero order were applied on data of diffusion release to explain release. The optimized formulation (F1) shows the zero order release.

A simple, rapid and specific RP-HPLC method has been developed and validated for determination of Carvedilol in bulk and tablet formulations. Chromatographic separation was performed by Phenomenex Luna C-18 (250 x 4.6mm, 5μm particle size) column with a mobile phase consisting of a mixture of phosphate buffer, acetonitrile and methanol in the ratio (30:45:25 v/v/v), pH adjusted to 4.8 with ortophosphoric acid. The mobile phase was was filtered through a 0.45μ cellulose nitrate filter, sonicated for 15 min and delivered at a flow rate of 1ml/min. Detection was performed at a wave length of 241 nm at ambient temperature. Linearity was obtained in a concentration range of 30 to130 µg/ml with a correlation coefficient (r2) of 0.999. The limit of detection and limit of quantification were 1.08 and 3.24 μg/ml, respectively. No interference of excipients in determining tablet formulation; identical results were obtained like that of the standard sample.  The proposed RP-HPLC method is simple, accurate, precise, rapid and economical to be employed for routine analysis of carvedilol in pharmaceutical dosage forms.