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 …


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.


febrile – medical word relating to fever

Foetal membranes

foetal membranes are the membranes surrounding the foetus.

Foetoplacental circulation

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

fulminant liver disease

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

free radical

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, …


Fibroscan – a non-invasive ultrasound scan that measures the ‘elasticity’ or stiffness of the liver. i-Base video of a FibroScan on YouTube.


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.


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

Fusion inhibitor

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.

Fungus (fungi)

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


frequency – how often.


fetal – of the unborn baby.

Fixed dose combination (FDC)

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