Metoxepin was developed as an antiemetic, neuroleptic and antihistamine agent. This drug has never been marketed.

Impromidine is a highly potent and specific histamine H2 receptor agonist used diagnostically as a gastric secretion indicator. The value of impromidine as an effective acid-secretory stimulant is limited by its tendency to cause cardiovascular side-effects, that mediated by H2-receptors in the cardiovascular system.

Piclopastine is an antihistamine agent.

Rocastine (AHR-11325) is a potent, nonsedating antihistamine with a rapid onset of action. This H1-antagonist effectively protected guinea pigs challenged with a lethal dose of histamine. It has also been mentioned in patents as a candidate to treat eye conditions and cough/cold mixtures (in which the lack of sedative effects from a non-sedating antihistamine would be especially useful in children, because daytime sedation is especially undesirable in this group). However, information on current use is not available and other second-generation, non-sedative antihistamines are available.

Trenizine is a diphenylmethyl piperazine derivative. It is a vasodilator, antiemetic, antihistamine and anti-anaphylactic agent.

Nemazoline (A-57219) is a nasal decongestant. It has alpha 1-agonist/alpha 2-antagonist activity and was more effective and long-acting than oxymetazoline on canine nasal mucosa, in-vitro and in-vivo. Upon intranasal administration to dogs, the compound was devoid of systemic effects up to a concentration 1000 times that needed for local decongestant effect (1.65 micrograms, atomized from a 1 microgram mL-1 solution) suggesting limited mucosal absorption. After nasal administration to rats for 15 days at a concentration 1000 times greater than that required for nasal decongestion, no mucosal tissue toxicity or systemic effects were seen.

Fuprazole was developed as a bronchodilator that has never been marketed. Information about the current use of this compound is not available.

Dimelazine is a sedative, antihistaminic agent.