Hydroxyzine pamoate is a form of the antihistamine hydroxyzine that is made from the salt of pamoic acid. Hydroxyzine pamoate goes by alternate names such as Equipose, Masmoran, Paxistil and Vistaril. The drug is used to relieve the symptoms of allergic reactions.
Hydroxyzine was the first antihistaminergic drugs to be created. It was synthesized in 1956 by Belgian biopharmaceutical manufacturer Union Chimique Belge (UCB). Almost immediately, the United States Food and Drug Administration (FDA) approved of the drug, and U.S.-based Pfizer Incorporated began to sell it. As the world’s premier vendor of pharmaceuticals, Pfizer was instrumental in the subsequent widespread use of hydroxyzine.
Available as a prescription medication, hydroxyzine pamoate is most commonly manufactured as a 10-, 25- or 50-milligram (mg) tablet for dosage. It is, however, also made as a 25-, 50- or 100-mg capsule, a 5-milliliter (mL) syrup bottle with a dosage of 10 mg per teaspoon, a 5-mL pharmaceutical suspension with a dosage of 25 mg per teaspoon, and 25- and 50-mg-per-mL injections. Hydroxyzine pamoate is typically taken two to four times daily.
Hydroxyzine pamoate is considered a member of the diphenylemethane and piperazine classes of organic compounds. Diphenylemethane is named after the replacement of two hydrogen atoms with phenyl rings in the chemical compound methane. Piperazine refers to a compound that contains two opposing nitrogen atoms in a ring that comprises six parts.
Hydroxyzine pamoate is primarily used for curbing itching, and in particularly chronic urticaria, better known as the hives, which can be brought about by allergic reactions. This is linked to an organic nitrogen called histamine, which causes itching by releasing chemical messengers via linkage of its receptors to cells. Hydroxyzine pamoate prevents histamine from performing this activity. It also battles the allergies that generate the itching symptom.
Other types of ailments can be treated with hydroxyzine pamoate. It is also used to take care of anxiety, irritability, excitement, nausea and insomnia. There are some instances in which it can be applied to hyperalgesia, a condition characterized by increased response to pain. For its various applications, hydroxyzine is also referred to as an analgestic, hypnotic, sedative and anxiolytic.
Side effects of hydroxyzine pamoate include chest congestion, drowsiness, dizziness, headache, skin reddening and upset stomach. More serious side effects include muscle weakness, increased anxiety and breathing difficulty. The FDA places hydroxyzine in the middling pregnancy category C of the agency’s classification of pharmaceutical risk posed to pregnant women.