Rapamycin, also known by the generic name of sirolimus. is an immunosuppressive drug designed to prevent organ rejection after transplants, and is particularly useful in kidney transplant patients. It works by inhibiting cytokine (small cell-signalling protein molecules created and secreted by the body’s immune system) production by selectively blocking their transcriptional activation. In addition to its immunosuppressant properties, rapaymycin also has antifungal properties.
As mentioned, the primary use of rapamycin is to control the risk of rejection in renal transplant patients, and it is generally prescribed in combination with cyclosporine and corticosteroids. The drug is often prescribed in an oral solution bottle with a syringe for self-medicating patients to administer the correct dose into 2 fluid ounces of water or orange juice (patients are then advised immediately to drink a further four ounces of water or orange juice to wash this down).
Rapamycin has potential applications far beyond organ transplant care, however. In various different studies, the drug has been shown to extend the lifespan of mice, and could even be used to treat Alzheimer’s, to treat autism and to treat HIV. Because it affects the immune system, it is perhaps least surprising that rapamycin might be used to inhibit the spread of the HIV virus, and future studies will determine whether it could even be used to prevent HIV infection, an exciting prospect for medical science.
The autism application was found out when researchers were exploring the potential for rapamycin to treat the congenital condition tuberous sclerosis complex, or TSC. Sirolimus has been shown to show some success in treating this condition which leads to the growth of benign tumours inside internal organs, and it was discovered that in mice rapamycin regulates the same proteins as the TSC gene but in other parts of the body. Doses of sirolimus were shown to increase the intelligence of autistic mice to a similar level as non-autistic mice over the course of just several days.
So there are many current uses, and potential future uses of rapamycin. Strict contraindications for the drug are limited mostly to patients who have shown hypersensitivity to sirolimus or any of its derivatives. There are a few caveats, however. Women taking rapamycin are advised to use contraception before, during and even up to 12 weeks after taking the drug to avoid complications associated with damping the immune system during any pregnancy.
In addition, patients are warned to take precautions not to become over-exposed to strong sunlight while on a course of rapamycin because of the increased chances of developing skin cancer through UV exposure. Hats, long sleeves and high factor suncream are very much required for rapamycin patients.
Finally, Flexyx also mentions that rapamycin can affect patient response to vaccinations, and live vaccines (such as measles, mumps, rubella and typhoid among others) should be avoided while a patient is on a course of immunosuppressants.
Rapamycin is a useful but potent drug, and care should be taken by medical professionals when administering it and by patients when taking it. The unfortunate side-effects of suppressing the immune system are infinitely preferable to post-transplant organ failure, however, so it is worth the inconvenience and limited risks.