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Posted on 02.23.01
UNC CERTs Investigator Monitors Anti-HIV Drug Levels
By Sue Tolleson-Rinehart, PhD and Starr L. Nicely
Dr. Phillip D. Walson, a pediatrician, pharmacologist, and UNC CERTs partner at Cincinnati Children's Hospital, knew that the ability of drugs to help women and children with HIV could be affected by the way they took the drugs and how their bodies handled them.
Dr. Walson decided to develop an assay, or screening test, that could measure the levels of anti-HIV drugs called protease inhibitors in the bloodstream. With this assay, Dr. Walson and his colleagues would be able to see whether the circulating levels of the drugs were actually too high or too low, because of some problem with the way the drug was taken or absorbed.
This is important because too high a circulating level of the drug can be toxic to the patient. On the other hand, too low a drug level will not reduce the amount of HIV virus present and, in fact, might help create a drug-resistant version of the virus.
Walson's assays turned up some surprises: giving anti-HIV drugs to babies with water can flush the drugs through babies' systems before they have a chance to work. Giving drugs with infant formula solves the problem.
In another case, the assay showed high levels of protease inhibitor in a child. The child's parent had readjusted the dose of the drug without telling anyone. Some patients were not getting their drugs at all: one child's mother was too ill herself to medicate her child, but it took the assay to uncover the problem.
These cases show that there may be a big difference between what a doctor prescribes and what is at work in the body. Walson's assays can help doctors measure anti-HIV drug levels rapidly and reliably.
This will ensure that people are getting the level of drugs that they need, neither too much nor too little, and also should help reduce the incidence of drug-resistant viruses and the cost of caring for patients with HIV.