Shital S. Panchal

Formulation strategies for drug delivery of tacrolimus: An overview

Tacrolimus (FK 506) is a potent macrolide lactone immunosuppressive agent used for prophylaxis of organ rejection after transplantation and graft-versus-host disease after bone marrow transplantation in patients. Moreover, tacrolimus is a drug of choice in the treatment of atopic dermatitis for decreasing side effects associated with the use of topical corticosteroids. In spite of its success in ensuring graft survival, therapeutic use of tacrolimus is complicated due to its narrow therapeutic index (between 5 and 15 ng/ml). Tacrolimus has a large inter-/intra-patient variability in pharmacokinetics profile and a poor oral bioavailability because of its poor solubility, P-gp efflux, marked pre-systemic metabolism by CYP3A in the enterocytes and liver first pass effect. Several formulation approaches such as oily solution, solid dispersions, complexation with cyclodextrins, liposomes etc., have been investigated to improve oral delivery of FK 506. In this review, we have discussed various formulation approaches that have been undertaken by various researchers to solve the problems related to the drug delivery of tacrolimus.

Self micro-emulsifying drug delivery system of tacrolimus: Formulation, in vitro evaluation and stability studies

Background: Tacrolimus has poor solubility in water ranging from 4 to 12 μg/mL. The oral bio availabilities of tacrolimus is poor and exhibits high intra and inter-subject variability (4-89%, average 25%) in the liver and the kidney transplant recipients and in patients with renal impairment. Aim: The present study deals with the development and characterization of self-micro-emulsifying drug delivery system to improve the oral bioavailability of poorly soluble drug tacrolimus. Materials and Methods: Solubility of the tacrolimus was estimated in various oils, surfactants, and co-surfactants. Various in vitro tests such as percentage transmittance, emulsification time, cloud point, precipitation, and thermodynamic stabilities were used to find out optimized formulations. Optimized liquid self micro-emulsifying (SMEDDS) were characterized by particle size analysis and converted in solid by using the Florite RE as an adsorbent, which is further characterized by differential scanning calorimetry (DSC), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and particle size analysis. Results: The optimized liquid SMEDDS formulation contained 10% Lauroglycol FCC as an oil, 60% Cremophor RH, and 30% PEG (polyethylene glycol) 400 as a surfactant and co-surfactant respectively. The optimized liquid and solid SMEDDS showed higher drug release than the marketed capsule and pure API (active pharmaceutical ingredient) powder. For optimized liquid SMEDDS and solid SMEDDS, the globule sizes were found 113 nm and 209 nm respectively. The solid state characterization of solid-SMEDDS by SEM, DSC, FTIR, and XRD revealed the absence of crystalline tacrolimus in the solid-SMEDDS. Shelf-lives for liquid SMEDDS and solid SMEDDS were found to be 1.84 and 2.25 year respectively. Conclusions: The results indicate that liquid SMEDDS and solid SMEDDS of tacrolimus, owing to nano-sized, have potential to enhance the absorption of the drug.

A review on phyto-pharmacological potentials of Euphorbia thymifolia L.

Euphorbia thymifolia L. (Euphorbiaceae) is a small branched, hispidly pubescent, prostate annual herb, commonly known as laghududhika or choti-dudhi. The leaves, seeds and fresh juice of whole plant are used in worm infections, as stimulant, astringent. It is also used in bowel complaints and in many more diseases therapeutically. The present work is an extensive review of published literature concerning phytochemical and pharmacological potential of E. thymifolia. Data was searched and designed using various review modalities manually and using electronic search engines with reference to all aspects of E. thymifolia and was arranged chronologically. Complete information of the plant has been collected from the various books and journals since the last 32 years, internet databases, etc., were searched. Compiled data reflects the safety and therapeutic efficacy of the plant. This will be helpful for researchers to focus on the priority areas of research yet to be explored and in scientific use of the plant for its wide variety of traditional therapeutic claims and also as to find out new chemical entities responsible for its claimed traditional activities.

Protective effect of oryzanol isolated from crude rice bran oil in experimental model of diabetic neuropathy

Several studies have implicated the involvement of poor glycemic control and oxidative/nitrosative stress in the development of diabetic neuropathic pain, an important microvascular complication affecting more than 50% of diabetic patients. However, lack of understanding of the underlying etiology, development of tolerance, inadequate relief and possible toxicity associated with classical analgesics warrant the investigation of the novel agents. Therefore, the present study was carried out to investigate the effect of oryzanol (OZ), a commercially-important potent antioxidant component isolated from from crude rice bran oil (cRBO), in streptozotocin (STZ)-induced diabetic neuropathy in rats. After eight weeks, diabetic rats developed neuropathy which was evident from decreased tail-flick latency (thermal hyperalgesia) and increased nociceptive behavior during the formalin test. This was accompanied by decreased motor coordination based on the evaluation of neuromuscular strength. Na+ K+ ATPase, a biochemical marker associated with the development of diabetic neuropathy, was significantly inhibited in the sciatic nerve of diabetic animals. The activities of antioxidant enzymes and lipid peroxidation levels were significantly elevated in diabetic rats, indicating the involvement of oxidative stress in diabetic neuropathy. Chronic treatment with oryzanol (OZ) (50 and 100 mg/kg) per oral (p.o.) and standard drug glibenclamide (Gl) (10 mg/kg, p.o.) significantly attenuated the behavioral as well as biochemical changes associated with diabetic neuropathy. The findings provide experimental evidence to the protective effects of OZ on hyperglycemia-induced thermal hyperalgesia and oxidative stress which might be responsible for diabetes induced nerve damage.

Anti-Inflammatory and Antioxidative Stress Effects of Oryzanol in Glaucomatous Rabbits

Purpose. γ-Oryzanol works by anti-inflammatory and radical scavenging activity as a neuroprotective, anticancer, antiulcer, and immunosuppressive agent. The present study was conducted to investigate effect of oryzanol in acute and chronic experimental glaucoma in rabbits. Methods. Effect of oryzanol was evaluated in 5% dextrose induced acute model of ocular hypertension in rabbit eye. Chronic model of glaucoma was induced with subconjunctival injection of 5% of 0.3 ml phenol. Treatment with oryzanol was given for next two weeks after induction of glaucoma. From anterior chamber of rabbit eye aqueous humor was collected to assess various oxidative stress parameters like malondialdehyde, superoxide dismutase, glutathione peroxidase, catalase, nitric oxide, and inflammatory parameters like TNF-α and IL-6. Structural damage in eye was examined by histopathological studies. Results. In acute model of ocular hypertension oryzanol did not alter raised intraocular pressure. In chronic model of glaucoma oryzanol exhibited significant reduction in oxidative stress followed by reduction in intraocular pressure. Oryzanol treatment reduced level of TNF-α and IL-6. Histopathological studies revealed decreased structural damage of trabecular meshwork, lamina cribrosa, and retina with oryzanol treatment. Conclusions. Oryzanol showed protective effect against glaucoma by its antioxidative stress and anti-inflammatory property. Treatment with oryzanol can reduce optic nerve damage.

Anti-obesity activity of chloroform-methanol extract of Premna integrifolia in mice fed with cafeteria diet

Aim of the study: Aim of the present study was to evaluate the anti-obesity activity of chloroform:methanol extract of P. integrifolia (CMPI) in mice fed with cafeteria diet. Materials and Methods: Female Swiss Albino mice were divided into six groups, which received normal and cafeteria diet, standard drug simvastatin (10 mg/kg) and CMPI (50, 100 and 200 mg/kg) daily for 40 days. Parameters such as body weight, body mass index (BMI), Lee index of obesity (LIO), food consumption, locomotor behavior, serum glucose, triglyceride, total cholesterol, high density lipoprotein (HDL), low density lipoprotein (LDL), very low density lipoprotein (VLDL), atherogenic index, organ weight and organ fat pad weight were studied for evaluating the anti-obesity activity of P. integrifolia. High performance liquid chromatography (HPLC) fingerprint profile of chloroform-methanol extract was also studied using quercetin as the reference standard. Results: There was a significant increase in body weight, BMI, LIO, food consumption, organ weight (liver and small intestine), organ fat pad weight (mesenteric and peri-renal fat pad) and in the levels of serum glucose, triglyceride, total cholesterol, LDL and VLDL with a significant decrease in locomotor behavior (ambulation, rearing, grooming) and HDL level in cafeteria diet group. Animals treated with CMPI showed dose dependent activity. P. integrifolia (200 mg/kg) supplementation attenuated all the above alterations, which indicates the anti-obesity activity. HPLC fingerprint profile of CMPI showed two peaks in the solvent system of 50 mm potassium diphosphate (pH-3 with ortho phosphoric acid): Methanol (30:70 v/v) at 360 nm. Conclusion: Present findings suggest that, CMPI possessed anti-obesity activity that substantiated its ethno-medicinal use in the treatment of obesity.

Effect of potassium channel openers in acute and chronic models of glaucoma

Purpose: Glaucoma is characterized by increased intraocular pressure (IOP). The effect of nicorandil and pinacidil on IOP in experimentally induced acute and chronic models of glaucoma and the mechanism of action involved were studied. Methods: New Zealand white rabbits were used for the study. After the measurement of IOP, nicorandil (1%), pinacidil (1%), and pilocarpine as standard (1%) were instilled topically into the left eye. The other eye served as control. Dextrose (5%) was used to induce acute glaucoma. IOP changes were recorded every 15 minutes until the pressure became normal. Freshly prepared a-chymotrypsin solution was introduced in the posterior chamber to induce chronic glaucoma. Rabbits with ocular hypertension were selected for the study. Similar drug solutions were used to study the effect on IOP. Glibenclamide, pilocarpine, and indomethacin (1%) were used to study the mechanism of action of both drugs. The IOPs were measured just prior to drug instillation and at suitable time intervals using a tonometer. Results: Pretreatment with topical nicorandil and pinacidil significantly lowered the rise in IOP in the acute model. Nicorandil and pinacidil initially caused rise in IOP for 15–30 minutes in chronic glaucoma. This was followed by reduction in IOP. Pretreatment with indomethacin and pilocarpine did not modify the effect of nicorandil and pinacidil on IOP. Pretreatment with glibenclamide blocked IOP from the lowering effect of nicorandil and pinacidil. Conclusion: The oculohypotensive effect shown by these drugs appears to be attributable to enhancement of the aqueous humor outflow. This effect is perhaps mediated through potassium channels.

Evaluation of genotoxic and modulatory effects of Nyctanthes arbor-tristis calyx extract and the isolated crocin in Ames’ assay

Abstract Flowers of the plant Nyctanthes arbor-tristis (NAT) are widely used in the traditional medicinal systems of several Asian countries. In the present study, potential genotoxicity and modulatory effects of ethanolic extract of NAT flower calyx (NAT FCE) and crocin, a carotenoid principle were evaluated employing standard Salmonella assay. Experiments evaluating the genotoxic potential of NAT FCE and crocin, with and without the S9-activation in TA 98, TA 100 and TA 102 showed a lack of increase in revertant mutants. Evaluation of modulatory effects of NAT FCE and crocin, without the S9, showed significant decrease in the number of 4-nitro-o-phenylenediamine-, sodium azide- and ethyl methanesulfonate-induced revertants. However, with S9, NAT FCE and crocin moderately increased the 2-aminoanthracene-induced revertants in TA 98; they moderately decreased revertants in TA 100 and TA 102. Both NAT FCE and crocin have been shown to be non-genotoxic and to be able to modulate responses of standard mutagens.

Reduction of liver tumerogenic effect of N-nitrosodiethylamine by treatment with ɣ-oryzanol in Balb/C mice

In recent years, naturally occurring phytochemicals with antioxidant capacity have generated surmount interest in their therapeutic usage against a wide range of pathological and toxicological conditions. The present study was designed to evaluate potential of ɣ-oryzanol (OZ), a bio-active natural antioxidant against hepatocellular carcinoma effect of the carcinogen N-nitrosodiethylamine in Balb/c mice. OZ inhibited the proliferation of Hep-3B cell line in concentration dependent manner. Administration of OZ to N-nitrosodiethylamine induced Balb/c mice for 16 and 32 weeks showed reduction in levels of liver injury markers, restored the levels of liver tumor markers, suppressed the hepatic nodular incidence and multiplicity, and favorably modulated the liver antioxidant status in a time dependent manner. Histologically, no obvious signs of neoplasia in the liver tissues were observed in OZ supplemented rats with N-nitrosodiethylamine induced liver tumerogenesis. OZ was found to be effective for reduction of N-nitrosodiethylamine induced hepatocellular carcinoma.

Effect of γ-oryzanol on hyperlipidemia and thrombus formation in mice treated with poloxamer-407

Mater ia l and methods : Swiss albino male mice were divided into four groups. Animals were treated with atorvastatin (2 mg/kg, p.o., as the standard drug) and OZ (100 mg/kg, p.o.) up to 3 days. On the 3rd day poloxamer-407 (500 mg/kg, i.p.) was administered to induce hyperlipidemia. Thrombotic plaque was induced using FeCl3 (50%). Animals were sacrificed after 24 h from induction of hyperlipidemia. Blood was collected for estimation of lipid profile, coronary disease risk factors, blood coagulation parameters i.e. APTT and PT. Liver was isolated for estimation of oxidative stress parameters. Further, the effect of therapy on thrombus formation was observed by histopathology of carotid artery.