Glossary

Intermediate level resistance – when a drug still has some impact on HIV, but when this is reduced (compared to wild-type HIV) because there is some drug resistance.

half-life (T1/2) the time taken a drug to clear from the highest concentration to half this level. Drugs have different half-lives in different compartments (ie half-life in blood can be different from the half-life inside a cell). It take 5 x the half-live for a drug to be considered cleared.

What happens when you take a drug?

preclinical refers to the early development stage for a new drug, before any testing on humans. This includes they laboratory and animal tests. Preclinical studies will not always show what will happen when people use the drugs, but can provide a guide to serious problems that could occur.

chorionic villus sampling – test in which cells around an embryo are removed and examined to detect genetic abnormalities.

resistance – when the genetic structure of an organism (virus, bacteria, fungi etc) changes in a way that stops a drug from working. See mutation.

Changing treatment and drug resistance.