Microprocessor in controlled transdermal drug delivery of anti-cancer drugs.

Microprocessor controlled transdermal delivery of anticancer drugs 5-Fluorouracil (5-FU) and 6-Mercaptopurine (6-MP) was developed and in vitro evaluation was done. Drugs were loaded based on the pharmacokinetics parameters. In vitro diffusion studies were carried at different current density (0.0, 0.1, 0.22, 0.50 mA/cm2). The patches were evaluated for the drug content, thickness, weight, folding endurance, flatness, thumb tack test and adhesive properties all were well with in the specification of transdermal patches with elegant and transparent in appearance. In vitro permeation studies through human cadaver skin showed, passive delivery (0.0 mA/cm2) of 6-MP was low. As the current density was progressively increased, the flux also increased. the flux also increased with 0.1 mA/cm2 for 15-20 min, but it was less than desired flux, 0.2 mA/cm2 for 30 min showed better flux than 0.1 mA/cm2 current, but lag time was more than 4 h, 0.5 mA/cm2 current for more than 1 h, flux was >159 microg/cm2 h which was desired flux for 6-MP. 5-FU flux reached the minimum effective concentration (MEC) of 54 microg/cm2 h with 0.5 mA/cm2 current for 30-45 min, drug concentration were within the therapeutic window in post-current phase. We concluded from Ohm's Law that as the resistance decreases, current increases. Skin resistance decrease with increase in time and current, increase in the drug permeation. Interestingly, for all investigated current densities, as soon as the current was switched off, 5-FU and 6-MP flux decreased fairly, but the controlled drug delivery can be achieved by switching the current for required period of time.

Microprocessor-controlled iontophoretic drug delivery of 5-fluorouracil: pharmacodynamic and pharmacokinetic study.

PURPOSE: The purpose of this study was to fabricate monolithic 5-fluorouracil (5-FU) transdermal patch with microprocessor- controlled iontophoretic delivery, to evaluate the pharmacodynamic effects on Dalton's lymphoma ascites (DLA) induced in Balb/c mice, and to study pharmacokinetics in rabbits. MATERIALS AND METHODS: The transdermal patches were prepared by solvent casting method; a reprogrammable microprocessor was developed and connected to the patches. DLA cells were injected to the hind limb of Balb/c mice (10 animals/group). In the first group of mice 5-FU was administered i.v. (12 mg/kg). In the second group of mice, transdermal patches (20 mg/patch/animal) were installed and kept for 10 consecutive days, while the third (control) group was kept without any treatment. The tumor diameter was measured every 5th day for 30 days, and the animal survival time and death pattern were studied. The electric current density protocol of 0.5 mA/cm(2) for 30 min was used in the pharmacokinetic study in rabbits. RESULTS: There was a significant reduction in tumor volume in the animals treated with monolithic matrix 5-FU transdermal patch compared to untreated controls and i.v. therapy. Tumor volume of the control animals was 5.8 cm(3) on the 30th day, while in 5-FU with transdermal patch delivery animals it was only 0.23 cm(3) (p <0.05). DLA cells tumor-bearing mice treated with 5-FU with transdermal patch had significantly increased lifespan (ILS). Control animals survived only 21+/-1 days after the tumor inoculation, while i.v. 5-FU and 5-FU patches animals survived 24+/-2.7 days and 39.5+/-1.87 days with ILS of 25.58% and 88.09%, respectively (p <0.01). There was significant sustained release of 5-FU through microprocessor-controlled patches and half-life was significantly higher (p <0.05) compared to the i.v. route. CONCLUSION: Cytotoxic concentration of 5-FU can be achieved through the transdermal drug delivery and effective therapeutic drug concentration can be maintained up to 24 h, with less toxicity. A new generation of transdermal drug delivery systems based on microprocessor-controlled iontophoresis is in the late stages of development and promises to enhance the treatment of local and systemic medical conditions. The incorporation of microprocessor into these systems has been an important advancement to ensure safe and efficient administration of a wide variety of drugs.

Physicochemical and pharmacokinetic parameters in drug selection and loading for transdermal drug delivery.

Skin of an average adult body covers a surface of approximately 2 m2 and receives about one-third of the blood circulating through the body. The transdermal route of administration cannot be employed for a large number of drugs. The rationality of drug selection based on pharmacokinetic parameters and physicochemical properties of the drug are the important factors to be considered for deciding its suitability of drug for delivery by transdermal route.