Drugs from the same therapeutic or chemical class are usually given names with the same stem. Stems are mostly placed word-finally, but in some cases word-initial stems are used. They are collected in a publication informally known as the Stem Book.
Examples are:
* -anib for angiogenesis inhibitors (e.g. pazopanib)
* -anserin for serotonin receptor antagonists, especially 5-HT antagonists (e.g. ritanserin and mianserin)
* -ant for various receptors antagonists (e.g. aticaprant and rimonabant)
* -arit for antiarthritic agents (e.g. lobenzarit)
* -ase for enzymes (e.g. alteplase)
* -azepam or -azolam for benzodiazepines (e.g. diazepam and alprazolam)
* -caine for local anaesthetics (e.g. procaine or cocaine)
* -cain- for class I antiarrhythmics (e.g. procainamide)
* -coxib for COX-2 inhibitors, a type of anti-inflammatory drugs (e.g. celecoxib)
* -mab for monoclonal antibodies (e.g. infliximab); see Nomenclature of monoclonal antibodies
*-- for cannabinoid receptor agonists (e.g. cannabidiol, dronabinol)
* for cannabinoid receptor antagonists 
* -olol for beta blockers (e.g. atenolol)
* -pril for ACE inhibitors (e.g. captopril)
* -sartan for angiotensin II receptor antagonists (e.g. losartan)
* -tinib for tyrosine kinase inhibitors (e.g. imatinib)
* -vastatin for HMG-CoA reductase inhibitors, a group of cholesterol-lowering agents (e.g. simvastatin)
* -vir for antivirals (e.g. aciclovir or ritonavir)
**  for antiretroviral protease inhibitors (e.g. darunavir)
* arte- for artemisinin antimalarials (e.g. artemether)
* cef- for cephalosporins (e.g. cefalexin)
* io- for iodine-containing radiopharmaceuticals (e.g. iobenguane)
* -vec for gene therapy vectors (e.g. alipogene tiparvovec)
* -meran for messenger RNA products (e.g. tozinameran)