|MadSci Network: Biochemistry|
Dear Patrick, Consult your doctor regarding the first half of your question. Keep in mind that medicines that are prescribed to be delivered orally do NOT necessarily all work when applied to skin directly, and vice versa - in fact it is a very, very bad idea to self-dose and experiment with application methods without consulting a medical doctor. The second half of your question concerns the field of pharmacological dosage in general. This dosage is established experimentally. Normally, scientists would hypothesize the desired amount of drug, based on some perceived optimal, medicinally relevant concentration of the drug in blood, or serum, fat, muscle, etc. This concentration is then extrapolated into real life using complex calculations involving absorption, excretion, and metabolism parameters. Calculated values are nearly always off from what needs to be administered in real life, and therefore animal experiments are carried out with varied dosage patterns. Ultimately, dosage is confirmed or altered based on studies in healthy volunteers, and finally in patients, these two stages being parts of Clinical Trials - something that is extremely tightly regulated by the FDA and similar organizations. Clinical trials can involve thousands of people worldwide, and usually cost many millions of dollars which is why dosage is probably the most important parameter to get correct as early as possible because repeating trials with different dosage patterns can drive a company bankrupt. Hope this helps, A.G.E.
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