This is Part 2 of an update of an article that first appeared in Advance for Audiologists in 2000.
The Physicians Desk Reference lists adverse reactions for meclizine, noting that “Drowsiness, dry mouth and, on rare occasions, blurred vision have been reported.” But what about functional impact? Could meclizine potentially make your symptoms worse?
Kennedy et al. conducted psychomotor tests and questionnaires on healthy young adults after administering therapeutic doses of several different medications used for motion sickness, including meclizine and hyoscine (scopolomine). While their results showed no major decrease in several psychomotor tests, they did indicate that meclizine had a significant detrimental effect on balance tests involving standing on a balance beam. A possible caveat to this study is that the tests were performed within one to two hours of drug ingestion, while later studies showed that meclizine had its peak central nervous system effect nine hours after dosing.
Is “Buzzed” Balance the Same as “Drunk” Balance ?
Manning et al. explored the central nervous system effects of meclizine and dimenhydrate (Dramamine). Their results “demonstrate that both dimenhydrate and meclizine, in recommended doses, produce drowsiness and impaired mental performance greater than placebo.” These authors attempt to “interpret the meaning of the observed decrement in test scores” by comparing their results to the effects of ethanol (alcohol): “Ethanol serves as a unique drug to reference degree of impairment because there are epidemiologic data that relate to blood alcohol concentrations with a known risk (.07 percent) for being involved in a traffic accident.” Comparison of the data demonstrates that the effect of dimenhydrate and meclizine on mental reaction time is equal to that observed while blood alcohol levels were .04 percent to .06 percent.
Two recent studies demonstrate the efficacy of vestibular therapy vs. medication in improving postural control in patients with vestibular deficiency. Horak et al. compared “relative effectiveness of vestibular rehabilitation, general conditioning exercises and vestibular suppressant medication” on subjective dizziness and postural control. The medication group was treated with Valium or Meclizine, both centrally sedating medications. Over a six-week treatment period, all groups reported a reduction in symptoms, but only the vestibular rehabilitation group showed significant objective improvement in scores obtained from posturography and standing balance tests.
The use of centrally sedating medication may impede the benefits of vestibular rehabilitation therapy. Shepard et al. reported that patients taking vestibular suppressants, antidepressants, tranquilizers and anticonvulsants ultimately achieved the same level of compensation as patients not taking similar medications, but the length of therapy was significantly longer.
Antivert is helpful for vertigo associated with sudden acute vestibular asymmetry due to Menieres disease or vestibular neuronitis, but should be withdrawn once the acute symptoms have diminished. It is not recommended for complaints of unsteadiness, loss of balance, and dysequilibrium, whether of vestibular origin or not. Vertigo related to BPPV is better treated through canalith repositioning techniques.
The Bottom Line?
Long-term use of Antivert is inappropriate, and the drug may be overprescribed in the primary care setting.