contraceptionI realize that at the moment (in the US anyway), there are no long-acting reversible contraceptives for men available, but that they are under active research.
What is the state of the art in this field? At what stage is the research? Is it possible to predict when commercial availability might become a reality?
Currently, the long-lasting male contraceptive that seems the most promising is a 'vas-deferens blocker' - it's kind of like a vasectomy in the way that they both block sperm by affecting the vas deferens, but that's where the similarity ends.
An injection of a polymer gel is performed into the vas deferens (the tubes that take sperm from the testes). The gel sticks in place and prevents sperm from passing through.
This method is less invasive than a vasectomy and allegedly easily reversible, with the estimated life of the polymer being ~10 years.
Application of the polymer will not be major surgery, requiring only an injection and (potentially) a small incision - the procedure takes around 15 minutes - patients can leave the hospital immediately after an injection and resume their normal sex lives within a week.
The procedure appears to be reversible by flushing out/dissolving the polymer in the vas deferens with another injection (most likely sodium bicarbonate):
Recently-completed rabbit studies showed rapid restoration of sperm flow. This was accomplished by flushing the Vasalgel from the vas deferens with an injection of sodium bicarbonate (baking soda) solution. Additional preclinical studies are underway to further test the methods and efficacy of reversibility in larger animals. Until reversibility studies are done in men, Vasalgel should be thought of as a vasectomy alternative.
- Vasalgel FAQ
I currently know of two separate research streams with similar goals that are working on these solutions:
Reversible Inhibition of Sperm Under Guidance, or RISUG, has been in development for over 25 years in India. RISUG will cause partial blockage of the vasa deferentia, and disruption of the sperm that pass through it.
Sperm are present in the ejaculate after RISUG has been administered, however they all have broken cell membranes, making them unviable. It is believed that the sperm are literally 'torn apart' by the ionisation of the polymer.
According to statements made by Dr Guha, one of the lead researchers on RISUG, There has been only one unplanned pregnancy among partners of the 250 volunteers who have been injected with RISUG (apparently due to a problem with the administered injection).
RISUG is currently in 'stage 3 clinical' (human) trials:
Indian Council of Medical Research – RISUG
This Phase III trial of RISUG as a male contraceptive is enrolling men in 4 Indian cities: New Delhi, Udhampur, Jaipur, and Ludhiana. The purpose of the study is to test the contraceptive efficacy of RISUG in a large and varied group of men. After being given RISUG, volunteers will be asked to make regular follow up visits. The study is not open to foreigners; participants must live in the local area so they can make follow-up visits.
Not available outside of India (currently). Stage 3 Clinical trials have stalled due to lack of volunteers (before you jump on a plane: you have to be an Indian citizen to qualify!).
Currently there is no locked-in date for general release.
Very similar to RISUG, however this research is being conducted in the US by a non-profit and is attempting to achieve US FDA and regulatory approval (which RISUG currently is not).
The polymer being used for Vasalgel is also different to RISUG, however it has similar effects.
Unlike RISUG, Sperm are blocked (instead of broken):
In the past, RISUG (a different product) was described as working by shredding sperm by an electrical charge process as they went past the contraceptive that lined the walls of the vas deferens. Vasalgel makes no such claims.
- Vasalgel FAQ
Currently in Animal Trials:
Vasalgel is currently undergoing animal testing, product qualification and safety testing. Human trials are expected to start in 2016 (small trial) and 2017 (larger trials).
- Vasalgel FAQ
At this stage it is looking like potentially being released to the public in 2018:
...If everything goes well and with enough public support, we hope to get Vasalgel on the market as early as 2018.
- Vasalgel FAQ
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