Effect of skin surface temperature on transdermal absorption of flurbiprofen from a cataplasm

Effect of environmental temperature on transdermal drug penetration

The effect of environmental temperature on the penetration from matrix-type transdermal patch of non-steroidal anti-inflammatory drugs (NSAIDs) as model drugs was investigated using in vitro and in silico experiment. The patch was applied on the stratum corneum (SC) side of the skin. The dermal side of the skin was mounted on a diffusion cell. The donor compartment of the diffusion cell was filled with distilled water. The donor temperature was set at 2, 25, 37, and 47 °C, respectively. The receptor compartment was kept at 37 °C and filled with phosphate buffer solution during the experiment. The permeation of the drugs from patch increased with increasing the donor temperature. The rate of permeation increased exponentially with increasing skin surface temperature. The diffusion coefficient in the skin remained almost constant, while the skin surface concentration was correlated with the skin surface temperature. The plasma concentrations in human were simulated by SKIN-CAD(®) together with the in vitro penetration experiment. The plasma concentration quickly changed with varying the environment temperature.

Transdermal Delivery of Flurbiprofen: Permeation Enhancement, Design, Pharmacokinetic, and Pharmacodynamic Studies in Albino Rats

The enhancing effects of lemon oil on the transdermal penetration of flurbiprofen through rat skin invitro and in vivo was investigated. The maximum flux achieved by Isopropyl alcohol (IPA):Propylene glycol (PG) (70:30% v/v) solvent mixture was further increased by lemon oil. The flux of flurbiprofen through ethylene vinyl acetate microporous membrane was evaluated. The membrane altered the flux of flurbiprofen significantly. The reservoir type of transdermal patch was fabricated using flurbiprofen viscous system, ethylene vinyl acetate membrane, and backing film. Histological investigations were done on rat skin samples treated with solvent systems with or without penetration enhancer for 24 hr. No skin irritation was seen. Lemon oil produced more pronounced change in stratum corneum and the epidermis as compared with the control groups. The pharmacokinetics of flurbiprofen in albino rats following application of a transdermal patch for 24 hr was evaluated. The maximum plasma concentration (C(max)) and AUC(0-alpha) of the patch formulation was 1.7 and 1.6 times, increased respectively as compared with the control patch formulation. Quantity of the drug accumulated in the excised skin to which test patch formulation was applied was more than the one to which control patch formulation was applied. Anti-inflammatory effect in the Carrageenin-induced paw edema in rat was significantly higher than the control patch formulation.

Cataplasm-based controlled drug delivery: development and optimization of a novel formulation

The objective of the present study was to study the formulation variables involved in the development of a novel plasterlike preparation (cataplasm) and to optimize important formulation variables with an aim to maximize the in vitro release of the drug with minimum lag time. Cataplasm was prepared by dispersing a model drug (ibuprofen), humectant (glycerol), adhesive (Indopol H100), polymer (Carbopol C934P) with other formulation ingredients in a beaker with an open-blade impeller. The paste was cast on a nonocclusive backing membrane and dried overnight. The diffusion of the model drug was studied across a cellulosic membrane using Franz's diffusion cells. The amounts of three formulation variables, carbopol (X1), glycerol (X2), and indopol (X3) were studied at three levels, and a face-centered cubic design was used to maximize the flux. An optimization procedure for maximum flux and minimum lag time predicted a flux of 97.22 mcg/cm2/hr at X1 (2% w/w), X2 (11.75% w/w), and X3 (6%, w/w). An experimental patch prepared with the above concentrations yielded a flux of 90.7 mcg/cm2/hr.

External control of drug release and penetration: enhancement of the transdermal absorption of indomethacin by ultrasound irradiation

The effect of ultrasound (1 MHz) on transdermal absorption of indomethacin from an ointment has been studied in rats. Ultrasound energy was supplied for 10 min at a range of intensities (0.25, 0.5 and 0.75 W cm-2), energy levels commonly used for therapeutic purposes. The pronounced effect of ultrasound on transdermal absorption of indomethacin was observed for all three intensities studied. The mean AUC value (33.22 micrograms h mL-1) after irradiation at 0.75 W cm-2 was 3.4 times the control value (9.70 micrograms h mL-1).

The barrier function of the skin in relation to percutaneous absorption of drugs

There is currently a high level of interest in using the skin as a route for delivering drugs. The skin, however, provides an efficient barrier against percutaneous absorption of drugs. This barrier function can be ascribed to the macroscopical structure of the stratum corneum, which consists of alternating lipoidal and hydrophylic regions. For this reason, physico-chemical characteristics of the drug, such as partition coefficient and molecular weight, play an important role in determining the facility of percutaneous absorption. Another factor to consider in transdermal drug delivery, is the vehicle in which the drug is formulated as it acts on the release of drug from the formulation. Moreover, vehicles may also interact with human stratum corneum, thereby affecting its barrier function. Surfactants and penetration enhancers are well-known examples of the latter. Subsequently, dosing conditions, such as humidity, temperature and occlusion, also have their impact on the actual input (rate) of drug through human skin. Finally, all bits of information are combined to form a reasonably faithful picture of percutaneous absorption.