Rat studies showed meclizine increases the risk of developing cleft palate when given increased doses 25 to 50 times more than the recommended human dose. It is unknown if meclizine passes through breast milk. Studies conducted in child-bearing women have not shown an elevated risk of developing fetal abnormalities when taking meclizine. Meclizine is an FDA Pregnancy Category B drug. Caution is advisable when dosing for this population. Patients 65 years or older may be more sensitive to the effects of the usual adult dose due to the anticholinergic properties of meclizine.
For children 12 and older, dosing is similar to that of adults and adolescents. The drug is not approved for children less than 12 because safety and efficacy have not been established. Radiation-induced nausea and vomiting – Orally, 50 mg two to twelve hours before radiotherapy treatment Vertigo – Orally, 25 to 100 mg daily, and subsequent dosages depend upon clinical response. Patients can take subsequent dosages once every 24 hours. Motion sickness – Orally, 25 to 50 mg one hour before embarkation for protection against motion sickness. Meclizine's half-life is about 6 hours, the onset of action is about 1 hour, and the duration of action is approximately 8 to 24 hours. The drug can be taken without regard to food. Chewable tablets must be crushed or completely chewed before swallowing. Meclizine administration is chewable or non-chewable by oral tablets. Įxcretion: The drug is excreted as a metabolite in the urine and is excreted unchanged in the feces. Metabolism: The data on meclizine metabolism is limited, but according to in vitro metabolic studies, the dominant hepatic enzyme to metabolize meclizine was found to be CYP2D6. The drug reaches peak plasma levels roughly 3 hours after administration.ĭistribution: Meclizine's volume of distribution is unknown in humans because it has not had sufficient study. This effect also reduces vestibular incitation and labyrinth excitability.Ībsorption: Meclizine is absorbed post-oral administration. These effects result in the inhibition of signals through histamine neurotransmission from the nucleus of the solitary tract and the vestibular nuclei to the chemoreceptor trigger zone and vomiting center located in the medulla. This blocking effect occurs in the vomiting center and chemoreceptor trigger zone (CTZ) located in the medulla. The blocking actions on these receptors give meclizine its antiemetic and antivertigo properties. It also has central anticholinergic actions. Meclizine is a first-generation antihistamine (non-selective H1 antagonist). The elderly should proceed with caution due to some of the anticholinergic properties of meclizine, which may cause confusion, urinary retention, amnesia, etc.
Extended use and hefty doses of meclizine may cause effects in breastfeeding or decrease the milk supply, especially in combination with sympathomimetic drugs such as pseudoephedrine.
It is not known whether meclizine is excreted into breast milk. It is not thought to harm an unborn baby. It is safe to use to treat nausea and vomiting during pregnancy. The drug has not received approval for children under 12 years of age because safety and efficacy have not been established. The recommended dosages for control of vertigo against vestibular diseases are between 25 to 100 mg daily, and subsequent dosages depend upon clinical response. Recommended dosages to control motion sickness are between 25 to 50 mg one hour before embarkation for protection against motion sickness-additional dosages are repeatable once every 24 hours. The drug can be taken orally with or without food by tablet. Meclizine off-label can also be an option to treat the same symptoms caused by viral illnesses, gastrointestinal infections, pregnancy, or radiation therapy. It also treats vertigo symptoms caused by vestibular diseases that commonly affect the inner ear, such as Meniere’s disease. These symptoms include dizziness, nausea, and vomiting. Meclizine, an FDA- approved drug, is a first-generation antihistamine used for the symptomatic management of motion sickness.
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