No abstract

Parenteral route is preferred for low molecular weight heparin (LMWH) due to poor oral bioavailability. Biodegradable formulation components were evaluated for possible interactions between the physical mixtures using differential scanning calorimetry. LMWH and an absorption enhancer papain were encapsulated in bovine serum albumin matrix and four formulations were spray-dried (MS.1, MS.2, MS.3, MS.4). Formulations were evaluated for product yield, particle size, particle charge and encapsulation efficiency. In vitro release assessed in pH 7.2 phosphate buffer saline (PBS) revealed a burst release effect (60%) for all the formulations except MS.1. In vivo studies performed in male Sprague Dawley rats showed an enhancement in drug absorption for the MS.2 and MS.3 formulations because of papain action on paracellular tight junctions. A significant increase in LMWH oral bioavailability was demonstrated by MS.3 (21%), among the formulations encapsulated with papain.

Conventional anticoagulants such as unfractionated heparin and warfarin have numerous limitations compared with low-molecular-weight heparin (LMWH). However, the need for repetitive parenteral administration is still a major disadvantage of LMWH, and the absorption of macromolecules such as LMWH across the gastrointestinal tract is very poor. Due to these problems with oral delivery of LMWH, transdermal delivery can be considered as an alternate route of administration. However, overcoming the skin barrier is necessary for the transport of larger molecules across the stratum corneum. This review focuses on the transdermal delivery of LMWH, providing a brief overview of heparin delivery via invasive and oral routes and discusses the advantages of using LMWH rather than heparin for transdermal delivery, and the primary reasons for poor permeability of LMWH. Various strategies employed for transdermal delivery of heparin are summarized, and chemical and physical enhancement techniques or suitable formulations that can be used to improve transcutaneous penetration and various chemical enhancers that act on the skin by different modes of action are discussed. We also consider physical approaches such as iontophoresis, electroporation, and ultrasound, as well as combination strategies to deliver heparin. The developments in physical and chemical enhancement strategies over the past decade are summarized. In addition, recent novel approaches such as microneedles employed for the transdermal delivery of LMWH are also discussed.

Based on the results obtained, these TPGS-emulsified PCL nanoparticles proved to be potential carriers for the delivery of protein/peptide drugs.