Evaluation of irritation and sensitisation of two 50 microg/day oestrogen patches

Comparison of efficacy and local tolerability of estradiol metered-dose transdermal spray to estradiol patch in a network meta-analysis

OBJECTIVES

Transdermal hormone replacement therapy is preferred for menopausal vasomotor symptoms. Our purpose was to compare the efficacy and local tolerability of a patch and a metered-dose transdermal spray that have never been directly compared.

METHOD

The relative change in the number of hot flushes between baseline and week 12 was selected as an efficacy indicator and the frequency of local skin reactions as a tolerability indicator. A network meta-analysis was performed to compare efficacy. Application site tolerability was compared descriptively.

RESULTS

Overall 46 studies were identified. In the efficacy analysis, eight active treatment arms and a placebo arm were determined based on the estradiol daily dose (from 14 μg to 50 μg). All but one had a significantly higher effect on relative change in the number of hot flushes than did the placebo. We found no evidence for different efficacy of the patch and the metered-dose transdermal spray. The latter performed better in terms of local skin reactions.

CONCLUSION

The patch and the metered-dose transdermal spray seem to have the same efficacy on vasomotor symptoms in estradiol hormone replacement. The local tolerability of the metered-dose transdermal spray is favorable.

Dermal and Transdermal Drug Delivery Systems: Current and Future Prospects

The protective function of human skin imposes physicochemical limitations to the type of permeant that can traverse the barrier. For a drug to be delivered passively via the skin it needs to have adequate lipophilicity and also a molecular weight <500 Da. These requirements have limited the number of commercially available products based on transdermal or dermal delivery. Various strategies have emerged over recent years to optimize delivery and these can be categorized into passive and active methods. The passive approach entails the optimization of formulation or drug carrying vehicle to increase skin permeability. Passive methods, however do not greatly improve the permeation of drugs with molecular weights >500 Da. In contrast active methods that normally involve physical or mechanical methods of enhancing delivery have been shown to be generally superior. Improved delivery has been shown for drugs of differing lipophilicity and molecular weight including proteins, peptides, and oligonucletides using electrical methods (iontophoresis, electroporation), mechanical (abrasion, ablation, perforation), and other energy-related techniques such as ultrasound and needless injection. However, for these novel delivery methods to succeed and compete with those already on the market, the prime issues that require consideration include device design and safety, efficacy, ease of handling, and cost-effectiveness. This article provides a detailed review of the next generation of active delivery technologies.

Transdermal drug delivery systems: skin perturbation devices

Human skin serves a protective function by imposing physicochemical limitations to the type of permeant that can traverse the barrier. For a drug to be delivered passively via the skin it needs to have a suitable lipophilicity and a molecular weight < 500 Da. The number of commercially available products based on transdermal or dermal delivery has been limited by these requirements. In recent years various passive and active strategies have emerged to optimize delivery. The passive approach entails the optimization of formulation or drug carrying vehicle to increase skin permeability. However, passive methods do not greatly improve the permeation of drugs with molecular weights >500 Da. In contrast, active methods, normally involving physical or mechanical methods of enhancing delivery, have been shown to be generally superior. The delivery of drugs of differing lipophilicity and molecular weight, including proteins, peptides and oligonucletides, has been shown to be improved by active methods such as iontophoresis, electroporation, mechanical perturbation and other energy-related techniques such as ultrasound and needleless injection. This chapter details one practical example of an active skin abrasion device to demonstrate the success of such active methods. The in vitro permeation of acyclovir through human epidermal membrane using a rotating brush abrasion device was compared with acyclovir delivery using iontophoresis. It was found that application of brush treatment for 10 s at a pressure of 300 N m(-2) was comparable to 10 min of iontophoresis. The observed enhancement of permeability observed using the rotating brush was a result of disruption of the cells of the stratum corneum, causing a reduction of the barrier function of the skin. However, for these novel delivery methods to succeed and compete with those already on the market, the prime issues that require consideration include device design and safety, efficacy, ease of handling, and cost-effectiveness. This chapter provides a detailed review of the next generation of active delivery technologies.