Part of it is a lack of financial incentives on the part of the drug companies. Most pharmaceutical research is aimed at marketing drugs.
Take the example of hypertension, which is more prevalent among blacks than whites. At the moment, all of the major antihypertensive families are available as generic drugs. The best way to help black people quickly is to do a comparative study of drugs already on the market. No drug company is going to do that because they won't be able to capture the value if the drugs are generic.
Maybe a drug company could try to develop a drug which is particularly good for blacks, but it will take a decade, may not work, won't sell as well (fewer people), and then it will be an expensive new drug and people will complain about the cost.
Take the example of hypertension, which is more prevalent among blacks than whites. At the moment, all of the major antihypertensive families are available as generic drugs. The best way to help black people quickly is to do a comparative study of drugs already on the market. No drug company is going to do that because they won't be able to capture the value if the drugs are generic.
Maybe a drug company could try to develop a drug which is particularly good for blacks, but it will take a decade, may not work, won't sell as well (fewer people), and then it will be an expensive new drug and people will complain about the cost.