Towards the design of a subcutaneous implant to deliver L-thyroxine

NOCENT, M; CORRALES, M; NICOLA, JP

Congreso; XVIII Latin American Thyroid Congress; 2021

Latin American Thyroid Society

According to WHO 4% to 8% of the world’s population suffer hypothyroidism. L-thyroxine monotherapy is considered
the standard of care for hypothyroidism treatment. Patients under thyroid hormone replacement therapy frequently requires a selfadministered
daily tablet of L-thyroxine. Retrospective studies revealed that adherence to treatment remains a concern among patients
with hypothyroidism. Poor compliance with L-thyroxine therapy regularly included forgetfulness, taking the medicine on an empty
stomach same time before food intake or just being hassled about their treatment plan. Subcutaneous contraception implant is a longterm
contraceptive option that consists in a flexible toothpick-sized plastic rod placed under the skin of the upper arm through an
ambulatory surgical procedure. The implant involves subdermal time-release of synthetic progestin, which allows effective contraception.
Objectives: Considering the benefits of subcutaneous contraception implants, we sought to design a subcutaneous implant to deliver
thyroxine for thyroid diseases. During the develop step of the design process, we analyzed implant requirements, polymer selection,
design considerations and hormone diffusion through the implant. Results: Implantable controlled release systems releases a low,
steady dose of hormone for a long period of time. The following requirements were identified: biocompatibility, sterility, control
release of the drug, low side effects, easy to recover to finish the medication, simple and economic production. The controlled release
of the drug from the implant system relies on the nature of polymer (biodegradable or non-biodegradable), drug diffusion through the
polymer, drug solubility in the polymer, nature of polymer-drug interactions, initial drug load, size and geometric shape of the implant,
polymer-drug proportion. The main advantages and limitations of subdermal implants include long-term treatment without requiring
the user’s or provider’s attention, small dose required to obtain therapeutic action, drug levels in plasma are maintained at desired
levels continuously, and drug adjustment is readily available after microsurgical replacement of the implants. Conclusion: The design
and subsequent implementation of a subcutaneous implant to deliver L-thyroxine provides and a new panorama for the treatment of
thyroid diseases that require hormone replacement therapy, in order to optimize compliance to treatment.