Skin spray contraceptive next big thing
Birth control methods may shortly become even more convenient, writes Stephen Pincock
ALMOST 50 years after women first began taking the pill, Australian researchers are working on what they think could be the next major breakthrough in avoiding pregnancy — a contraceptive spray. If early results bear fruit, women may one day simply spray an invisible, odourless preparation onto the inside of their arm — no pills, implants or devices.
This method — if conclusively shown to work — may also have the advantage of being less sensitive to missed or late doses, a problem with daily contraceptive pills.
‘‘ It’s a concept that is highly acceptable to a lot of women,’’ says researcher Ian Fraser from the University of Sydney. ‘‘ There are a minority of women who find current methods not to their liking — and some who like the concept of doing things a little differently.’’
The technology for delivering contraceptives through the skin has been developed by Acrux, a small Melbourne firm founded by researchers from Monash University.
Their device looks rather like a large asthma inhaler. A woman would place it against the forearm and push a button to deliver through the skin a controlled dose of hormones as contained in a pill.
The so-called ‘‘ transdermal’’ delivery method has already been shown to work for purposes other than birth control. In July last year approval was granted in the US for marketing of the Acrux system for delivering hormones across the skin to treat menopause symptoms. The company is also planning a large trial using their system to deliver testosterone as a treatment for men with a condition known as male hypogonadism.
The company has been working for several years on spray-on contraceptives, but the first formal results only appeared in a scientific journal in December.
In that paper, Fraser, a professor of reproductive medicine, and doctor Edith Weisberg, director of research at the Sydney Centre for Reproductive Health Research at Family Planning NSW, describe a study that included six healthy post-menopausal women.
Each received five daily doses of a contraceptive hormone called Nestorone, a derivative of progesterone that has the highest antiovulatory potency of all the progestogens currently available.
The researchers wanted to assess whether the Acrux system could deliver hormone into the women’s bloodstream in quantities that would be sufficient to stop ovulation women still of childbearing age.
Although post-menopausal women wouldn’t use the system in real life, they were ideal to study because their bodies contain lower levels of natural hormones that could confuse the results, Fraser says.
The results, published in the journal Contraception (2007;76:432-438), were encouraging. They showed ‘‘ the feasibility of achieving serum levels of Nestorone sufficient to block ovulation and potentially provide effective contraception’’, the authors wrote.
Doctor Deborah Bateson, medical coordinator of Family Planning NSW, who wasn’t involved in the study, says she is cautiously optimistic about the findings. ‘‘ It’s early days obviously, but the exciting thing is that they showed that it is a viable concept.’’ For her, a contraceptive spray would be useful because it might offer women another choice for avoiding pregnancy. ‘‘ To increase choices is generally a good thing to do.’’
Since the contraceptive pill hit the Australian market in January 1961, those choices have expanded significantly. Women can now choose patches, intra-uterine devices, diaphragms, implants and other methods for contraception.
Still, the pill remains far and away the most commonly reported method. One recent analysis of Australia’s 2001 National Health Survey, published in the Journal of Biosocial Science (2007;36:735-44), showed that more than three-quarters of all women aged 18-49 had used the contraceptive pill, including more than half of those under age 20.
A spray might overcome some of the problems associated with other methods, Bateson said. ‘‘ Contraceptive patches, for example, do come with their problems, particularly in a country like Australia where people go to the beach a lot. A once-a-day spray is a very attractive option. You can’t smell it or see it, and you can administer it yourself.’’
Women may also be interested to know that the Acrux spray-on technology has very close ties to sunscreen.
The product’s roots can be traced back some 20 years, to the labs of researchers Barrie Finnin and Barry Reed from the Victorian College of Pharmacy, now part of Monash University.
The two men were looking for ways to deliver drugs across the skin using creams or
in lotions, and had tried a host of approaches when they decided sunscreen to the mix.
‘‘ We were looking at things that might control hyperpigmentation of the skin,’’ Finnin recalls. ‘‘ We discovered that when you include sunscreen in the preparation, the other drugs you included got across.’’
Soon, the researchers discovered that the chemicals doing the job of ferrying drugs across the skin were a group of molecules designed to block ultraviolet light.
‘‘ It is just a coincidence that they also have these other properties,’’ said Finnin. ‘‘ It’s just different to add one of those fortunate things. I would like to say I was clever enough to have predicted it, but I didn’t.’’
It may have been a fluke, but Finnin and Reed quickly realised its value. Then, a PhD student named Tim Morgan showed that if you deliver the mix of sunscreen ingredients and drugs via aerosol or spray, it increased their absorption through the tough outer layers of the skin even further.
‘‘ At that time, we realised we had something that was potentially very commercially valuable,’’ Finnin said. By 1997 they had provisional patents on their invention, and in 1998 they founded Acrux to help raise funds for further research.
‘‘ It’s essentially an offshoot of sunscreen technology,’’ says Ian Fraser. He explains that a dose of hormones delivered with the Acrux system is absorbed across the outer layers of skin within 30 seconds, and then sits in the deeper layers of the skin where they are slowly released into the bloodstream over the following 36 hours.
‘‘ You’ve got this reservoir in the deeper layers of the skin,’’he said. In the study his group published last year, there was still a substantial amount of the contraceptive in the bloodstream of the women 27 hours after the final dose.
This slow-release mechanism might have a significant benefit for those women who find it hard to time the pill exactly.
‘‘ The majority of women miss a pill from time to time, and a minority miss a pill every month,’’ he says. ‘‘ Most of the pregnancies that occur with women who are taking the pill are due to the difficulties in remembering to take it at a certain time every day.’’
With a spray that builds up a reservoir under the skin, ‘‘ it does mean that if you’re a bit late, or even miss your next dose, it doesn’t matter so much,’’ Fraser said.
Ultimately Acrux would like to develop a contraceptive spray that combines Nestorone with estrogen, in the same way that the most widely used contraceptive pills include both estrogen and progesterone.
CEO Jon Pilcher says testing of combinations is already under way.
‘‘ We’re currently running a trial in Melbourne and Brisbane with a daily combination,’’ he says. Results should be out by the middle of the year.
Under trial: Doctor Edith Weisberg with the Acrux spray-on applicator