surfactant

Tamoxifen Citrate (TC), an antiestrogenic drug, is used in both pre and post menopausal breast cancer treatment in women. One of the major causes of its poor bioavailability is attributed to its poor aqueous solubility. In this study an effort has been made to improve the aqueous solubility of the hydrophobic drug using methods like cosolvency and micellisation. Cosolvents (ethanol, polyethylene glycol-400), and surfactants [polyoxyethylene sorbitan monooleate (Tween-80), Poloxamer-407 and Poloxamer-188] were tested for their solubilizing potential. Solubility enhancement approaches showed variable degrees of increase in solubility of TC. Solubility studies with different concentrations of Ethanol and PEG-400 at 37°C showed that higher efficiency of increasing solubility by cosolvency was achieved with ethanol (6.10 fold) than that with PEG 400 (5.62 fold) while in case of varying concentrations of surfactants (tween 80, Poloxamer 188 and Poloxamer 407). Poloxamer 407 exhibited maximum potential in solubilizing TC in water (7.1 fold). However, among the solubilizing techniques and solubilizing agents used, micellization with polysorbate 80 as surfactant was found to be the most effective. Data suggests that using simple techniques, improvement of solubility of TC can be attained which may help in improving its poor bioavailability.

Nanoemulsions are only kinetically stable. However, the long term physical stability of nanoemulsions (with no apparent flocculation or coalescence) makes then unique and they are sometimes referred to as ‘Approaching thermodynamic stability. The inherently high colloid stability of nanoemulsions can be well understood from a consideration of their stearic stabilization (when using non-ionic surfactants and /or polymers) and how this is affected by the ratio of the adsorbed layer thickness to droplet radius. Successful ocular drug delivery has largely eluded solution due to, the physiological constraints imposed by the protective mechanisms of the eye that lead to poor absorption of drugs with very small fractions (less than 5%) of the instilled dose penetrating the cornea and reaching the intraocular tissues. Low drug contact time and poor ocular bioavailability due to drainage of solution, tear turnover and its dilution or lacrimation are the problems associated with conventional systems. Novel systems offer manifold advantages over conventional systems as they increase the efficiency of drug delivery by improving the release profile and also reduce drug toxicity. Conventional delivery systems get diluted with tear, washed away through the lacrimal gland and usually require administering at regular time intervals whereas novel emulsions are stable, have improved solubility, required reduced dosing frequency and release drug for prolonged periods of time. The aim of this review focuses on micro and nanoemulsions between 1 and 200 nm with a mean droplet size of about 40nm) for ocular drug delivery.

The aim of this study was to prepare and evaluate sublingual fast-disintegrating mucoadhesive tablet (mFDT) containing a poorly soluble drug (carvedilol CAR) to avoid the first pass metabolism and to improve its bioavailability with reduction in dose and also dose related side effects. The tablets were prepared by direct compression method containing solid dispersion of surfactant and drug. The prepared tablets were tested for weight variation, hardness, drug content uniformity, bioadhesive strength and in vitro drug dissolution. The in vitro release of carvedilol was performed under sink conditions (phosphate buffer of pH 6.8, 37±0.5 ºC, 25 rpm) using USP‐XXIV dissolution apparatus. The acceptable in vitro drug release profile was achieved with the formulation F2 which contains the drug and poloxamer in the ratio of 1:2 and superdisintegrant of 3%. The bioadhesive strength of formulation F2 was found to be 13.8 g. The tablets (formulation F2) containing 6.25 mg of carvedilol exhibited > 80 % of drug release within 10 min. FTIR, XRD and DSC studies showed no evidence of interactions between drug, surfactant, and excipients. The tablets apart from fulfilling all official and other specifications, exhibited higher rate of release. The mucoadhesive fast disintegrating drug delivery system of carvedilol for sublingual delivery could be successfully formulated.

A drug should be present in dissolved or solublized state before producing its therapeutic effect however in current market more than 40% drugs are poorly soluble in water. Such drugs exhibit poor dissolution rate and slow absorption throughout the gastrointestinal tract which leads to irregular bioavailability. Thus various techniques has been adopted for solubility and dissolution enhancement of poor water soluble drugs thereby bioavailability. Solubility plays an important role in achieving the desired plasma drug concentration. In this review article various techniques like solid dispersion, SLNs, SEDDS, dried emulsion were discussed for solubility and dissolution rate improvement of BCS class II anti hyperlipidemic drug Simvastatin. Amongst various method described in this review, solid dispersion was found to be most used technique by researcher as it provide ease in preparation and efficiency in terms of resolving the solubility and dissolution problems associated with Simvastatin.