The latest Phase I trials of the company's metered dose skin spray delivery technology (MDTS) tested out combinations containing both a progestin and an oestrogen.
The promising results mark a critical milestone in the development of the drug delivery system, given that over three quarters of the $6.7bn (€4.9bn) contraceptive market is made up of combination products.
The company's two trials focused on a nestorone (a fourth generation progestin) and synthetic oestrogen (ethinyl estradiol) combination, and a nestorone and natural oestrogen (estradiol) combination.
Both trials were carried out using Acrux' novel delivery device, which uses a hand-held applicator to deliver a fast drying formulation to the skin.
The liquid formulation consists of the progestin and oestrogen, skin penetration enhancers and a volatile solvent.
Each spray delivers 9 microlitres of the formulation to the skin, with the volatile component evaporating quickly to leave the formulation dry within a minute.
The contraceptive and the penetration enhancer are then absorbed and form a depot within the outer layer of the skin, from which the contraceptive is released into the bloodstream over a 24 hour period.
Daily top-ups of the spray restock the depot so that a steady level of contraceptive is released into the blood to provide effective contraceptive protection.
While the some aspects of the company's second trial (using estradiol) were inconclusive, the nestorone/ethinyl estradiol combination spray provided effective delivery of both drugs with blood concentrations within the range to provide effective contraception.
The fact that the spray technology successfully delivered the synthetic oestrogen, ethinyl estradiol, was a particular accomplishment for the company, given its prevalence in contraceptive therapies currently available.
"Given that over 80 per cent of all oral contraceptive products contain ethinyl estradiol, Acrux' ability to deliver this particular compound effectively is very significant for the commercial application of the transdermal spray technology," Nina Wilkins, Acrux business development director, told in-PharmaTechnologist.com.
"It goes without saying that positive results such as these will always trigger a variety of partnering discussions."
Back in February Acrux sealed a deal with Organon (the former human healthcare unit of Akzo Nobel bought up by Schering Plough for €11bn in March this year) to develop and commercialise contraceptives delivered via the Acrux technology.
For each contraceptive compound that Organon chooses to develop, Acrux may receive payments of $12-$16m on achievement of development and regulatory milestones, as well as royalties on worldwide sales of any products.
While Acrux is undertaking the early stage developmental work on the combination contraceptive sprays independently, the company will be seeking partners to assist with later stages of development and registration.
"We believe that this [result] not only reinforces the potential value of our relationship with Organon, but positions us strongly with other pharma companies that are actively innovating in the field of reproductive health," said Wilkins.
With contraceptive patches currently available generating hundreds of millions for pharma firms, Acrux believes this is an indication of how its spray devices could perform, and is confident that its spray devices will become real competitors when they hit the market in the next few years.
"The Acrux MDTS spray technology is not an expensive platform and therefore we envisage the commercially available spray product to be priced at a similar level to other contraceptive products," said Wilkins.
The product is anticipated to come with a month's supply of contraception and to have a shelf life of at least two years.
Acrux' most advanced product is EvaMist, and estradiol MDTS for the treatment of hot flushes in post-menopausal women.
The new drug application for the product was lodged with the US Food and Drug Administration (FDA) in September 2006, and the company anticipates EvaMist becoming available in the US in early 2008.
The next step in the development of the combination contraceptive will be to move on with a multi-dose Phase I study in the second half of 2007, designed to show whether therapeutic blood levels of the contraceptives are effectively maintained with once-daily dosing.