Novel formulation approaches for optimising delivery of anticancer drugs based on P-glycoprotein modulation.

Considerable research efforts have been directed towards understanding the enigma of P-glycoprotein (P-gp) in drug development and delivery. P-gp is a multi-specific drug efflux transporter that plays a significant role in governing the bioavailability of various anti-cancer drugs. Modulation of this efflux transporter by various traditional 'chemosensitisers' forms a distinctive approach in improving pharmacokinetics and conquering drug resistance.

Emerging significance of flavonoids as P-glycoprotein inhibitors in cancer chemotherapy.

Chemotherapy forms the mainstay of cancer treatment particularly for patients who do not respond to local excision or radiation treatment. However, cancer treatment by drugs is seriously limited by P-glycoprotein (P-gp) associated multi-drug resistance (MDR) in various tumor cells. On the other hand, it is now widely recognized that P-gp also influences drug transport across various biological membranes.

Effect of P-glycoprotein inhibitor, verapamil, on oral bioavailability and pharmacokinetics of irinotecan in rats.

The objective of present investigation was to study the effect of verapamil on the pharmacokinetics of irinotecan in order to evaluate the role of P-glycoprotein (P-gp) in irinotecan disposition. An in vitro study using Caco-2 intestinal cell monolayer was first carried out to determine the effect of verapamil on the function of intestinal P-gp. Verapamil (25mg/kg) was administered orally 2h before irinotecan oral (80 mg/kg) or intravenous (20mg/kg) dosing in female Wistar rats.

Development and validation of reversed phase liquid chromatographic method utilizing ultraviolet detection for quantification of irinotecan (CPT-11) and its active metabolite, SN-38, in rat plasma and bile samples: application to pharmacokinetic studies.

A new, simple, sensitive and specific reversed-phase high performance liquid chromatographic (HPLC) method using ultraviolet detection was developed and validated for the analysis of CPT-11 (lambda(max)=254 nm, 365 nm) and its major active metabolite, SN-38 (lambda(max)=380 nm) in rat plasma and bile. The sample pre-treatment from plasma involved a single protein precipitation step with cold acetonitrile. In case of bile, liquid-liquid extraction with dichloromethane: tert-butyl methyl ether (3:7) was carried out.

Probiotics: from functional foods to pharmaceutical products.

The concept of probiotics now has been around for more than a century, with its consumption increasing exponentially; owing to exciting scientific and clinical findings, limiting side effects of existing pharmaceutical agents and increased consumer demand for natural products. But, the evidence for their safety and efficacy has largely been anecdotal, lacking an integrated scientific basis. Clinical studies conducted with probiotics were of inadequate design and resulted in unreliable data.

Pre-clinical evidence for altered absorption and biliary excretion of irinotecan (CPT-11) in combination with quercetin: possible contribution of P-glycoprotein.

P-glycoprotein (P-gp) is found to play a very significant role in intestinal and biliary transport of irinotecan and its active metabolite, SN-38. This makes P-gp inhibition a logical strategy for improving irinotecan's oral efficacy and reducing its toxicity. The objective of the present study was to identify the most suitable P-gp inhibitor, amongst various commonly used herbal components via in vitro screening; followed by determination of in vivo effects in rats.

Solid self-nanoemulsifying delivery systems as a platform technology for formulation of poorly soluble drugs.

New drug discovery programs produce molecules with poor physico-chemical properties, making delivery of these molecules at the right proportion into the body a big challenge to the formulation scientist. The various options available to overcome the hurdle include solvent precipitation, micronisation/nanonization using high-pressure homogenization or jet milling, salt formation, use of microspheres, solid dispersions, cogrinding, complexation, and many others. Self-nanoemulsifying systems (SNES) form one of the most popular and commercially viable approaches for delivery of poorly soluble drugs exhibiting dissolution rate limited absorption, especially those belonging to the Biopharmaceutics Classification System II/IV.

Concurrent determination of topotecan and model permeability markers (atenolol, antipyrine, propranolol and furosemide) by reversed phase liquid chromatography: utility in Caco-2 intestinal absorption studies.

A simple, sensitive, specific and high-resolution reversed-phase liquid chromatographic method utilizing ultraviolet detection has been developed and validated for simultaneous determination of topotecan and four intestinal permeability markers (atenolol, antipyrine, propranolol and furosemide) as suggested by US-FDA. Chromatography was carried out on C-18 column with mobile phase comprising water (pH 3.0) and acetonitrile gradient pumped at a flow rate of 1 ml min(-1).

Reversed-phase liquid chromatography with ultraviolet detection for simultaneous quantitation of indinavir and propranolol from ex-vivo rat intestinal permeability studies.

A simple, rapid, sensitive and specific reversed-phase high performance liquid chromatographic (RP-HPLC) method involving ultraviolet detection (lambda = 210 nm) was developed for analysis of indinavir along with propranolol in samples obtained from ex vivo intestinal permeability studies. Chromatography was carried out on C-18 column with mobile phase comprising of phosphate buffer-acetonitrile (68:32, v/v) pumped at flow rate of 1 ml/min. The proposed method has a short run time of 12 min and involves a simple sample preparation for the purpose of reducing permeability model artifacts and to concentrate the samples.