Why are some medications pills and some injection? How do the researchers determine which is best?


For example I take three different types of medication for migraines. One is a monthly injection, one is a dissolvable pill and another is just a regular pill I take. How do the researchers decide the best way for patients to take the pills?

Also I am terrible at chemistry so if anyone’s explanation includes that, please dumb it down as best as you can.

In: 2

Drugs go through first pass metabolism which means the that certain drugs can be inactivated if you take orally. Other drugs (IV formulations, sublingual and buccal routes) are administered to avoid becoming non-functional or having their ability to treat diminished by being given via an alternate route.

In general, injections are better in that more of the drug actually gets to what it is supposed to do. A large portion of the drug you take orally as a pill gets discharged of by the liver right after being digested. So pills put more strain on your liver for the set amount of effect. On the other hand, all injections run a small risk a trauma or infection, so they have their downsides too. This balance of upsides and downsides is what matters when choosing the form of medicine to use.

In very simple terms, some drugs won’t survive the passage through the stomach without losing effectiveness (administered by injection etc), others are fine and get absorbed (pill).

Generally taking medication by mouth is safest so that’s used unless it won’t work for some reason, most commonly because the stomach will destroy some drugs. Injections bypass the stomach but piercing the skin causes a danger of infection and sharp needles are dangerous in other ways, not to mention being more painful.

My migraine neurologist only gives me injection and dissolvable meds because my stomach is so sensitive I always end up vomiting regular pills up. So how the patient tolerates the meds is a factor.