febrile – medical word relating to fever

fetal – of the unborn baby.

Fibroscan – a non-invasive ultrasound scan that measures the ‘elasticity’ or stiffness of the liver.

i-Base video of a FibroScan on YouTube.

fibrosis – mild to moderate scarring of the liver (see cirrhosis)

fibrotest – a test which uses results from blood tests to predict liver damage and which may become an alternative option to liver biopsy in some patients.

fixed dose combination (FDC) – several drugs combined in one tablet at a standard dose.

foetal membranes are the membranes surrounding the foetus.

foetoplacental circulation is the blood supply in the foetus and placenta.

fold-change – a term relating to drug resistance after a phenotype resistance test.

4-fold resistance (also called a 4-fold loss in sensitivity) means you need to use four times the dose to get the same reduction in viral load.

Food and Drug Administration (FDA) – the US FDA is the government organisation that is responsible for approving and regulating human and animal medicines in the US. It is also responsible for the safety of other products including foods, cosmetics and tobacco.

See: www.fda.gov

formulation – the physical form that makes an active drug into a medicine.

Different formulations include

  • Pills (capsules or tablets).
  • Syrups or other oral solutions.
  • Injections.
  • Powders.
  • Creams or lotions.

A co-formulation is when two active drugs are combined. For example: when two active drugs are in the same pill.

free radical – a chemical produced after a molecular reaction, often containing oxygen, that has one ‘free’ unpaired electron on its outer surface. This makes it able to react and damage other cells, and perhaps increase progression of cardiovascular disease, cancers and aging. See antioxidant.

frequency – how often.

fulminant liver disease – sudden, rapid disease progression related to liver failure.

fungus (fungi) – parasitic organisms that include moulds, mildews, mushrooms and yeast.

fusion inhibitor – a type of HIV drug (an entry inhibitor). Fusion inhibitors stops HIV ‘fusing’ to a CD4 cell. T-20 (enfuvirtide, Fuzeon) is only currently licensed fusion inhibitor.

Drug targets in the virus life cycle.