Amodiaquine is a medication used to treat malaria, including Plasmodium falciparum malaria when uncomplicated. The mechanism of plasmodicidal action of amodiaquine is not completely certain. Like other quinoline derivatives, it is thought to inhibit heme polymerase activity. This results in accumulation of free heme, which is toxic to the parasites. The drug binds the free heme preventing the parasite from converting it to a form less toxic. This drug-heme complex is toxic and disrupts membrane function. The side effects of amodiaquine are generally minor to moderate and are similar to those of chloroquine. Rarely liver problems or low blood cell levels may occur. When taken in excess headaches, trouble seeing, seizures, and cardiac arrest may occur. After oral administration amodiaquine hydrochloride is rapidly absorbed,and undergoes rapid and extensive metabolism to desethylamodiaquine which concentrates in red blood cells. It is likely that desethylamodiaquine, not amodiaquine, is responsible for most of the observed antimalarial activity, and that the toxic effects of amodiaquine after oral administration may in part be due to desethylamodiaquine.

Tripelennamine (sold as Pyribenzamine by Novartis) is a drug that is used as an antipruritic and first-generation antihistamine. Histamine acting on H1-receptors produces vasodilatation, hypotension, flushing, headache, tachycardia, and bronchoconstriction. Histamine also increases vascular permeability and potentiates pain. Tripelennamine can be used in the treatment of asthma, hay fever, rhinitis, and urticaria, but is now less common as newer antihistamines have replaced it.

Mizolastine (Mizollen) is a long-acting H1 -antihistamine indicated for the symptomatic relief of seasonal allergic rhinoconjunctivitis (hay fever), perennial allergic rhinoconjunctivitis and urticaria. It blocks H1 receptors and is commonly fast-acting. It does not prevent the actual release of histamine from mast cells, just prevents it binding to receptors. Side effects can include dry mouth and throat

Pibutidine hydrochloride (IT-066), a novel histamine H2 receptor antagonist has powerful and long lasting antisecretory and antiulcer effects and is a useful antisecretory drug for treatment of peptic ulcer diseases.

Tiapride is a drug that selectively blocks D2 and D3 dopamine receptors in the brain. It is used to treat a variety of neurological and psychiatric disorders including dyskinesia, alcohol withdrawal syndrome, negative symptoms of psychosis, and agitation and aggression in the elderly. A derivative of benzamide, tiapride is chemically and functionally similar to other benzamide antipsychotics such as sulpiride and amisulpride known for their dopamine antagonist effects. Tiapride is marketed under various trade names and is widely available outside of the United States. The most common trade name for tiapride is Tiapridal, which is used throughout Europe, Russia, as well as parts of South America, the Middle East, and North Africa. It is also sold under different names in Italy (Italprid, Sereprile), Japan (Tialaread, Tiaryl, Tiaprim, Tiaprizal), Chile (Sereprid), Germany (Tiaprid, Tiapridex), and China (Tiapride).

Ebastine is an antihistamine which blocks H1-receptors through its carboxylic acid metabolite. Ebastine is indicated for the treatment of allergic rhinitis and chronic idiopathic urticaria.

Roxatidine is an histamine H2-receptor antagonist. Roxatidine is a potent and selective inhibitor of basal and stimulated gastric acid secretion through competitive blockade of H2-receptors. Total pepsin secretion is reduced in a dose-dependent manner. There is an independent mucosal protection action. Roxatidine is indicated for the treatment of peptic ulcer, gastro-oesophageal reflux disease, gastritis, upper gastrointestinal haemorrhage and Zollinger-Ellison syndrome also it can be used as a premedication before anaesthesia. Roxatidine possessed a robust estrogenic activity.

Osutidine (T-593) is a H2 receptor antagonist which was undergoing development by Toyama Chemical for the treatment of peptic/gastric and duodenal ulcers. It is a beta-hydroxyphenethylamine derivative with both antisecretory and cytoprotective properties. Osutidine inhibited the histamine-induced cAMP generation in a concentration-dependent manner. Osutidine suppressed the maximal response of the histamine-induced positive chronotropic response, indicating that the compound is unsurmountable H2-antagonists. The metabolism of Osutidine in humans may not differ from that of rodents and dogs. No clinically relevant accumulation occurred following repeated dosage. In the single oral and subcutaneous dose toxicity studies in rats, there were no dead animals. The oral LD50 value was greater than 5 g/kg for both sexes, and there was no abnormality in general signs. An oral formulation of the drug was in phase III clinical trials in Japan, however Toyama has dropped it from clinical development.

Dalcotidine is a histamine H2 receptor antagonist that demonstrated potent gastric mucosal protective activity on acute gastric lesions and duodenal ulcers. Dalcotidine was discontinued in phase III of clinical trials in Japan.

Rupatadine is characterised as a non-sedating H1 anti-histamine and platelet-activating factor (PAF) receptor antagonist. Rupatadine is indicated for the treatment of allergic rhinitis and urticaria. Rupatadine is a safe and well tolerated drug in patients over 2 years old, with no central nervous system or cardiovascular effects and it can be taken with or without foods.