Srinivas Mutalik

Once-Daily Sustained-Release Matrix Tablets of Nicorandil: Formulation and In Vitro Evaluation

The objective of the present study was to develop once-daily sustained-release matrix tablets of nicorandil, a novel potassium channel opener used in cardiovascular diseases. The tablets were prepared by the wet granulation method. Ethanolic solutions of ethylcellulose (EC), Eudragit RL-100, Eudragit RS-100, and polyvinylpyrrolidone were used as granulating agents along with hydrophilic matrix materials like hydroxypropyl methylcellulose (HPMC), sodium carboxymethylcellulose, and sodium alginate. The granules were evaluated for angle of repose, bulk density, compressibility index, total porosity, and drug content. The tablets were subjected to thickness, diameter, weight variation test, drug content, hardness, friability, and in vitro release studies. The granules showed satisfactory flow properties, compressibility, and drug content. All the tablet formulations showed acceptable pharmacotechnical properties and complied with in-house specifications for tested parameters. According to the theoretical release profile calculation, a oncedaily sustained-release formulation should release 5.92 mg of nicorandil in 1 hour, like conventional tablets, and 3.21 mg per hour up to 24 hours. The results of dissolution studies indicated that formulation F-I (drug-to-HPMC, 1∶4; ethanol as granulating agent) could extend the drug release up to 24 hours. In the further formulation development process, F-IX (drug-to-HPMC, 1∶4; EC 4% wt/vol as granulating agent), the most successful formulation of the study, exhibited satisfactory drug release in the initial hours, and the total release pattern was very close to the theoretical release profile. All the formulations (except F-IX) exhibited diffusion-dominated drug release. The mechanism of drug release from F-IX was diffusion coupled with erosion.

Interpenetrating network hydrogel membranes of sodium alginate and poly(vinyl alcohol) for controlled release of prazosin hydrochloride through skin

Interpenetrating network (IPN) hydrogel membranes of sodium alginate (SA) and poly(vinyl alcohol) (PVA) were prepared by solvent casting method for transdermal delivery of an anti-hypertensive drug, prazosin hydrochloride. The prepared membranes were thin, flexible and smooth. The X-ray diffraction studies indicated the amorphous dispersion of drug in the membranes. Differential scanning calorimetric analysis confirmed the IPN formation and suggests that the membrane stiffness increases with increased concentration of glutaraldehyde (GA) in the membranes. All the membranes were permeable to water vapors depending upon the extent of cross-linking. The in vitro drug release study was performed through excised rat abdominal skin; drug release depends on the concentrations of GA in membranes. The IPN membranes extended drug release up to 24 h, while SA and PVA membranes discharged the drug quickly. The primary skin irritation and skin histopathology study indicated that the prepared IPN membranes were less irritant and safe for skin application.

pH-responsive interpenetrating network hydrogel beads of poly(acrylamide)-g-carrageenan and sodium alginate for intestinal targeted drug delivery: synthesis, in vitro and in vivo evaluation.

In the present work, we synthesized pH-responsive interpenetrating network (IPN) hydrogel beads of polyacrylamide grafted κ-carrageenan (PAAm-g-CG) and sodium alginate (SA) for targeting ketoprofen to the intestine. The PAAm-g-CG was synthesized by free radical polymerization followed by alkaline hydrolysis under nitrogen gas. The PAAm-g-CG was characterized by elemental analysis, FTIR spectroscopy and thermogravimetric analysis (TGA). The drug-loaded IPN hydrogel beads were prepared by simple ionotropic gelation/covalent crosslinking method. The amorphous nature of drug in the beads was confirmed by differential scanning calorimetry and X-ray diffraction studies. The spherical shape of the beads was confirmed by scanning electron microscopic analysis. The beads exhibited ample pH-responsive behavior in the pulsatile swelling study. The ketoprofen release was significantly increased when pH of the medium was changed from acidic to alkaline. The beads showed maximum of 10% drug release in acidic medium of pH 1.2, and about 90% drug release was recorded in alkaline medium of pH 7.4. Stomach histopathology of albino rats indicated that the prepared beads were able to retard the drug release in stomach leading to the reduced ulceration, hemorrhage and erosion of gastric mucosa.

Preparation,In vitro, preclinical and clinical evaluations of once daily sustained release tablets of aceclofenac

The objective of the present study was to develop“once daily” sustained release tablets of aceclofenac by direct compression using hydroxypropyl methylcellulose-K4M (HPMC). The solubility studies of aceclofenac were conducted to select suitable dissolution media. The drug-excipient mixtures were subjected to preformulation studies. The tablets were subjected to physicochemical,in vitro drug release and stability studies. Preclinical (anti-inflammatory, analgesic, pharmacokinetic and toxicity studies) and clinical pharmacokinetic studies were conducted for optimized tablets. Based on the preformulation results, microcrystalline cellulose (MCC), dicalcium phosphate and spray dried lactose (SDL) were selected as directly compressible vehicles. Because of the incompatibility with aceclofenac, SDL was excluded from the study. The physicochemical properties of tablets were found within the limits. By comparing the dissolution profiles with the marketed product, the tablet containing HPMC (45%) and MCC (30%) along with talc and magnesium stearate (1% w/w, each) (Tablet B7) was considered as a better formulation. This tablet exhibited almost similar drug release profile in different dissolution media as that of marketed tablet. Tablet B7 was stable in accelerated conditions for 6 months. The composition of this tablet showed almost similar preclinical pharmacological activities compared to marketed tablet composition and did not exhibit any toxicity in rats and mice with respect to tested haematological and biochemical parameters along with body weight, food and water intake. The pharmacokinetic study in healthy human volunteers indicated that B7 tablet produced an extended drug release of drug upto 24 h as that of marketed product with almost identical pharmacokinetic parameters.

Antigen-Specific Suppression of Inflammatory Arthritis Using Liposomes

Existing therapies for rheumatoid arthritis and other autoimmune diseases are not Ag specific, which increases the likelihood of systemic toxicity. We show that egg phosphatidylcholine liposomes loaded with Ag (OVA or methylated BSA) and a lipophilic NF-κB inhibitor (curcumin, quercetin, or Bay11-7082) suppress preexisting immune responses in an Ag-specific manner. We injected loaded liposomes into mice primed with Ag or into mice suffering from Ag-induced inflammatory arthritis. The liposomes targeted APCs in situ, suppressing the cells’ responsiveness to NF-κB and inducing Ag-specific FoxP3+ regulatory T cells. This regulatory mechanism suppressed effector T cell responses and the clinical signs of full-blown Ag-induced arthritis. Thus, liposomes encapsulate Ags and NF-κB inhibitors stably and efficiently and could be readily adapted to deliver Ags and inhibitors for Ag-specific suppression of other autoimmune and allergic diseases.

Nanotechnology and Nanomedicine: Going Small Means Aiming Big

Nanotechnology is an emerging branch of science for designing tools and devices of size 1 to 100 nm with specific function at the cellular, atomic and molecular levels. The concept of employing nanotechnology in biomedical research and clinical practice is best known as nanomedicine. Nanomedicine is an upcoming field that could potentially make a major impact to human health. Nanomaterials are increasingly used in diagnostics, imaging and targeted drug delivery. Nanotechnology will assist the integration of diagnostics/imaging with therapeutics and facilitates the development of personalized medicine, i.e. prescription of specific medications best suited for an individual. This review provides an integrated overview of application of nanotechnology based molecular diagnostics and drug delivery in the development of nanomedicine and ultimately personalized medicine. Finally, we identify critical gaps in our knowledge of nanoparticle toxicity and how these gaps need to be evaluated to enable nanotechnology to transit safely from bench to bedside.

Preparation and evaluation of minoxidil gels for topical application in alopecia

In the present study four minoxidil gels were prepared using carbopol, hydroxypropyl cellulose, hydroxypropyl methylcellulose and combination of hydroxypropyl cellulose, hydroxypropyl methylcellulose for the treatment of alopecia. The gels were evaluated for drug content, viscosity determination, in vitro permeation (across dialysis membrane and mouse skin), skin irritation and stability at 4, 25 and 37° tests. The drug content of the gels was found to range from 96.40±0.57 to 98.10±0.32%. The viscosity of the gels ranged between 13,780±100 and 24,950±150 cps. The drug permeation across dialysis membrane from all the formulations at the end of 24 h was almost same and ranged between 92.05±1.52 and 93.52±1.95%. Although the difference is insignificant, the percentage release of drug was found to increase in the following order of the polymer composition: HPC>Carbopol>HPMC>HPMC+HPC. All the gel formulations released almost similar amounts of drug (90.05±1.92 to 91.56±1.65%) across the mouse skin; but the cumulative amount of drug permeated across dialysis membrane was more than that of the mouse skin. The marketed topical solution was found to diffuse almost 100% of drug across dialysis membrane and mouse skin at the end of 12 h. As supported by Higuchis equation, the drug release mechanism from all the gels was found to be diffusion dominated. The prepared gels did not produce any dermatological reactions and were well tolerated by the mice. The gels were found to be stable with respect to viscosity, drug content and physical appearance at all temperature conditions for 3 months.

Glutaraldehyde cross-linked chitosan microspheres for controlled delivery of Zidovudine

Zidovudine-Chitosan microspheres were prepared by a suspension cross-linking method. The chitosan was dissolved in 2% acetic acid solution and this solution was dispersed in the light liquid paraffin. Span-80 was used as an emulsifier and glutaraldehyde as cross-linking agent. The prepared microspheres were slight yellow, free flowing and characterized by drug loading, infrared spectroscopy (IR), differential scanning colorimetry (DSC) and scanning electron microscopy (SEM). The in-vitro release studies are performed in pH 7.4 buffer solution. Microspheres produced are spherical and have smooth surfaces, with sizes ranging between 60–210 µm, as evidenced by SEM and particle size analysis. The drug loaded microspheres showed up to 60% of entrapment and release was extended up to 18–24 h. Among all the systems studied, the 35% Glutaraldehyde crosslinked, microspheres with 1 : 6 drug/chitosan ratio showed 75% release at 12 h. The infrared spectra and DSC thermograms showed stable character of zidovudine in the drug loaded microspheres and revealed the absence of drug–polymer interactions. Data obtained from in vitro release were fitted to various kinetic models and high correlation was obtained in the Higuchi model. The drug release was found to be diffusion controlled.

Nasal insulin gel as an alternate to parenteral insulin: Formulation, preclinical, and clinical studies

The objective of the present study was to formulate insulin gel for intranasal administration and to evaluate with respect to in vitro release studies and hypoglycemic activity in animal model and healthy human volunteers. The insulin gel was formulated using the combination of carbopol and hydroxypropyl methylcellulose as gelling agent. The in vivo efficacy of insulin gel administered intranasally was assessed by measuring the blood glucose levels and serum insulin levels at specified time intervals in rats and humans. The use of bioadhesive nasal gel containing insulin not only promoted the prolonged contact between the drug and the absorptive sites in the nasal cavity but also facilitated direct absorption of medicament through the nasal mucosa. Absorption of the drug through the nasal mucosa was high in the first 0.5 to 1.5 hours of the study with a sharp decline in blood sugar and rise in insulin values corresponding to that decline in blood sugar. This study further demonstrates that administration of insulin intranasally in gel form is a pleasant and painless alternative to injectable insulin.

A combined approach of chemical enhancers and sonophoresis for the transdermal delivery of tizanidine hydrochloride

The effects of chemical enhancers and sonophoresis on the transdermal permeation of tizanidine hydrochloride (TIZ) across mouse skin were investigated. Parameters including drug solubility, apparent partition coefficient (APC), drug permeation, and degradation in skin were determined. Low frequency ultrasound was also applied in the presence and absence of chemical enhancers to assess whether drug permeation improved. APC values indicated that TIZ preferentially partitions into intercellular spaces and does not form a reservoir, with the drug also exhibiting good enzymatic stability in skin. Most of the enhancers studied significantly increased the permeation rate of TIZ through full thickness mouse skin in comparison with TIZ formulated in phosphate buffer. Maximum enhancement was observed for TIZ formulated as a suspension in 50% v/v aqueous ethanol containing 5% v/v citral. Sonophoresis significantly (p < 0.05) increased the cumulative amount of TIZ permeating through the skin at 15 and 30 min in comparison to passive diffusion. A synergistic effect was noted when sonophoresis was applied in the presence of chemical enhancers. The results suggest that the formulation of TIZ with an appropriate penetration enhancer may be useful in the development of a therapeutic system to deliver TIZ across the skin for a prolonged period, i.e. 24 hr. The application of ultrasound in association with chemical enhancers, such as the combination of 5% v/v citral in 50% v/v aqueous ethanol, could further serve as a non-oral and non-invasive drug delivery modality for the immediate therapeutic effect of muscle relaxants such as TIZ.