Dermal and transdermal macromolecule delivery using enhancer molecules and colloidal carrier systems. Part II: Percutaneous administration of heparin.

INTRODUCTION
Heparin is a commonly used anticoagulant administered either by intravenous or subcutaneous injection for a systemic effect, or topically for the treatment of peripheral vascular disorders.


OBJECTIVE
This study aimed to formulate heparin in non-ionic colloidal carrier systems (CCSs) having enhanced percutaneous absorption for systemic and topical administration.


METHODS
Five CCSs were developed and characterized for their rheological properties, droplet size and drug loading. The percutaneous absorption of heparin was evaluated in vitro using Franz diffusion cells with rats' skin and with the aid of a developed HPLC method. Furthermore, the efficacy of two developed heparin CCSs were tested percutaneously in rats by measuring the response against the time in comparison to subcutaneous administration.


RESULTS
The rheograms and droplets' size measurements showed that the developed drug delivery systems have Newtonian properties with a droplet size between 109 and 460 nm. As much as 500 mg of heparin could be loaded in around 5 mL CCS. Furthermore, using Franz diffusion cells, a diffusion rate of 19.216 ± 2.01 USP U/cm2.hr could be achieved for heparin-loaded CCSs. Moreover, the estimated percutaneous in vivo relative bioavailability in comparison to subcutaneous administration could reflect that at least more than 50% of the drug passed through the skin.


CONCLUSION
The developed novel non-toxic CCSs containing heparin can be a good candidate for percutaneous administration as alternative delivery systems for subcutaneous and intravenous invasive administration.