| nicotinic antagonists | Drugs that bind to nicotinic cholinergic receptors (receptors, nicotinic) and block the actions of acetylcholine or cholinergic agonists. Nicotinic antagonists block synaptic transmission at autonomic ganglia, the skeletal neuromuscular junction, and at central nervous system nicotinic synapses. (12 Dec 1998) |
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| dopamine antagonists | Drugs that bind to but do not activate dopamine receptors, thereby blocking the actions of dopamine or exogenous agonists. Many drugs used in the treatment of psychotic disorders (antipsychotic agents) are dopamine antagonists, although their therapeutic effects may be due to long-term adjustments of the brain rather than to the acute effects of blocking dopamine receptors. Dopamine antagonists have been used for several other clinical purposes including as antiemetics, in the treatment of tourette syndrome, and for hiccup. (12 Dec 1998) |
| opioid antagonists | Agents such as naloxone and naltrexone which have high affinity for opiate receptors but do not activate these receptors. These drugs block the effects of exogenously administered opioids such as morphine, heroin, meperidine, and methadone, or of endogenously released endorphins and enkephalins. (05 Mar 2000) |
| estradiol antagonists | Compounds which inhibit or antagonise the biosynthesis or action of estradiol. (12 Dec 1998) |
| excitatory amino acid antagonists | Drugs that bind to but do not activate excitatory amino acid receptors, thereby blocking the actions of agonists. (12 Dec 1998) |
| folic acid antagonists | Inhibitors of the enzyme, dihydrofolate reductase (tetrahydrofolate dehydrogenase), which converts dihydrofolate (fh2) to tetrahydrofolate (fh4). They are frequently used in cancer chemotherapy. (12 Dec 1998) |
| 5-hydroxy tryptamine antagonists | Agents which block serotonin receptors and hence interfere with the biological actions of serotonin (5-HT). (05 Mar 2000) |