Eli5 how come we can have transdermal patches and implants that last for months for things like birth control but not for other drugs

Question

I’m thinking things like levothyroxine that people have to take every day and are really important not to miss. Why can’t we have an implant or patch for this? It would be really helpful and possibly save lives.

In: 16

Answer 1

1. The skin is a good barrier. It is difficult to get drugs through it, the moleclue must among other things be small enough for it.

2. Cost. You mentioned levothyroxine, which dosage is adjusted according to the persons blood tests. This would require a wide variety of different strhengts on the market, which would cost a lot to develop and thus cost a lot for the consumer.