Clozapine prevents impaired NMDA receptor expression caused by NMDA receptor antagonists. Dexamethasone can increase the antiemetic effect of 5-HT receptor antagonists, such as ondansetron. Most NMDA receptor antagonists are metabolized in the liver. Certain substances are known as long-acting muscarinic receptor antagonists (LAMAs). Second line therapies include antihistamines, decongestants, cromolyn, leukotriene receptor antagonists, and nasal irrigation. Aprepitant belongs to the class of neurokinin-1 receptor antagonists medications. Many drugs have been found that lessen the risk of neurotoxicity from NMDA receptor antagonists. Pfizer researched several other related NK receptor antagonists. Other related opioid antagonists include nalodeine and samidorphan. There is growing evidence for the effectiveness of NMDA receptor antagonists for benzodiazepine-resistant catatonia. Hundreds of choline antagonists and enzyme inhibitors have been developed for research purposes. There were few if any adrenergic uncompetitive antagonists. Diuretic options for inpatient treatment include aldosterone antagonists (spironolactone) and loop diuretics. Phthalates block CB as allosteric antagonists. Animal experiments also suggest a benefit from serotonin antagonists.