Once-a-month oral contraceptive pill developed.


It is known that daily oral contraceptive pills provide women with a means to avoid pregnancy which can support their health and economical situation. For oral contraception to be effective, consistent drug levels must be maintained for prolonged periods, making the efficacy of these drugs dependent on patient adherence. According to the CDC the effectiveness of these daily contraceptive pills is closer to 91%, with one-third of users reportedly having missed their dose during a menstrual cycle; amongst women using oral contraceptive pills, the chance of pregnancy is about 9% every year. Now, a study from researchers at Brigham and Women’s Hospital develops a contraceptive pill that only needs to be taken once a month. The team states their slow-release pill, that can reside in the stomach for days or weeks, has achieved month-long delivery in preclinical models. The opensource study is published in the journal Science Translational Medicine.

Previous studies show several methods for long-term hormonal contraception exist presently including subcutaneous implants, intrauterine devices, vaginal rings, transdermal patches, and injectables. However, daily oral pills are favored by a sizeable fraction of the female population, mainly due to their availability, ease of use, the opportunity for self-administration, and rapid renewal of fertility upon discontinuation. Therefore a long-term oral pill would be highly desirable for the aforementioned reasons. The current study designs and provides preliminary testing of an oral pill in swine that proffers month-long delivery of a contraceptive drug, levonorgestrel.

The current study designs a six-armed drug release system joined by an elastomeric core, packaged into a gelatin covered capsule. The six polymeric arms are loaded with the oral contraceptive drug levonorgestrel and folded up into a small capsule that can be easily swallowed. Once in the stomach, the arms unfold and have a span that is larger than the opening of the human pylorus, helping the system stay in the stomach where it can release the drug over time. Results show the encapsulation of the contraceptive in polymer matrice successfully protects the drug from the gastric environment and enables sustained release.

The group explains the concentration of the oral contraceptive over time in a pig model was measured in the bloodstream in animals who had been given the coated extended-release form versus an immediate-release tablet. Results show for the tablet, dosage tapered off after six hours, and for the extended-release form, concentrations of the drug were recorded for up to 29 days. The lab concludes that pigs are recognized as having gastric anatomy comparable in dimension to humans, however, transit times are recognized to be slower, therefore a shorter drug release period using a longer residence in the stomach for humans may be needed.

The team surmises they have designed a capsule that can be swallowed once a month, reside in the stomach and release a drug to prevent pregnancy. For the future, the researchers state work is now underway to bring the extended-release pill closer to human trials by scaling up manufacturing processes and safety evaluations.

Source: Brigham and Women’s Hospital

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