Sex matters: Drugs can affect sexes differently - CBS News
Geege Schuman stashed this in XX
"How did it happen that for 20 some years, women, millions of them, were essentially overdosing on Ambien?"
Dr. Sandra Kweder: So if I took Zolpidem, and my brother took same dose, probably the maximum level of drug in my blood would be 45 percent higher than his maximum blood level.
Lesley Stahl: Now that sounds substantial—
Dr. Sandra Kweder: It is substantial.
But we discovered that that 45 percent difference between men and women had been known to the FDA all along. In the original FDA review of Ambien back in 1992, there was a page called “Effect of Gender,” where the FDA reviewer noted that two key measures of how much drug is in the bloodstream “were approximately 45 percent higher in females than in males.”
It's a miracle there aren't more medicine-related casualties.
I wonder if Big Pharma influences the reporting and thus our awareness of casualties.
This has been needed for a long time, also we should be dosing on size too ie a 85lb female probably shouldn't be taking the same dose as a 325lb male.
The only dosing that has historically been more specific is pediatric; which is based on the weight of the child.
There has been a little bit of interest in using Compounding Pharmacies; which make a medicine specifically for one person, but the only thing I've personally heard of it being used for the most, is Hormone Replacement Therapy, but I guess it is used for quite a bit of reasons, but does usually cost more than traditional drugs.
Compounding Pharmacies per Wikipedia
Patients with unique or unusual medication needs Physicians may prescribe an individually compounded medication for a patient with an unusual health need. This allows the physician to tailor a prescription to each individual. Compounding preparations are especially prevalent for:
- Patients requiring limited dosage strengths, such as a very small dose for infants
- Patients requiring a different formulation, such as turning a pill into a liquid or transdermal gel for people who cannot swallow pills due to disability
- Patients requiring an allergen-free medication, such as one without gluten or colored dyes
- Patients who absorb or excrete medications abnormally
- Patients who need drugs that have been discontinued by pharmaceutical manufacturers because of low profitability
- Patients facing a supply shortage of their normal drug 
- Children who want flavored additives in liquid drugs, usually so that the medication tastes like candy or fruit
- Veterinary medicine, for a change in dose, change to a more easily-administered form (such as from a pill to a liquid or transdermal gel), or to add a flavor more palatable to the animal. In the United States, compounded veterinary medicine must meet the standards set forth in the Animal Medicinal Drug Use Clarification Act (AMDUCA) 
- Many types of bioidentical hormone replacement therapy 
It's not just dosage size but the effects of multiple medicines when combined.