What is Cinnarizine?
Cinnarizine is a medication belonging to the diphenylmethylpiperazine group, first synthesized by Janssen Pharmaceutica in 1955 [1.3.3]. It functions as both a first-generation antihistamine and a calcium channel blocker [1.3.3, 1.6.5]. This dual mechanism of action makes it effective in treating a variety of conditions. It is widely used in many countries, including the UK, Mexico, and others in Europe, for managing nausea and vomiting associated with motion sickness, vertigo, tinnitus, and Ménière's disease [1.2.1, 1.3.3, 1.6.4]. Cinnarizine works by interfering with signal transmission between the inner ear's vestibular apparatus and the brain's vomiting center [1.6.3]. It also improves microcirculation in the brain by inhibiting calcium influx in vascular smooth muscle cells, which helps relax blood vessels [1.6.1, 1.6.5].
Primary Uses of Cinnarizine
- Motion Sickness: It is highly regarded for its efficacy in preventing travel sickness with potentially less drowsiness than some other options [1.2.1, 1.4.5].
- Vestibular Disorders: It helps control symptoms like vertigo, dizziness, and tinnitus by acting as a vestibular sedative [1.2.4, 1.6.4].
- Circulatory Issues: Due to its vasodilating effects, it's sometimes used for peripheral arterial disease [1.6.6].
The Core Reason for Unavailability in the US: Lack of FDA Approval
The fundamental reason cinnarizine is not sold in the United States is that it has not been approved for marketing by the U.S. Food and Drug Administration (FDA) [1.2.2, 1.3.2]. The FDA has a rigorous approval process that all new drugs must pass to be legally marketed and sold. Cinnarizine is also unavailable in Canada for similar regulatory reasons [1.2.1, 1.3.3].
Calcium Channel Blocking Properties
A primary factor contributing to its non-approval is its function as a calcium channel blocker [1.2.1]. While this property contributes to its therapeutic effects on vertigo and circulation, it also places the drug in a different regulatory category than simple antihistamines. The FDA requires extensive data to prove both the safety and efficacy of a drug for its intended use. Cinnarizine's multimodal action, which includes blocking L- and T-type voltage-gated calcium channels, requires a complex evaluation of its effects on the cardiovascular system and beyond [1.6.1].
Significant Side Effect Concerns
Cinnarizine carries a risk of serious side effects that have likely influenced its regulatory status in the U.S.
- Drug-Induced Parkinsonism: One of the most significant concerns is that cinnarizine is a leading cause of drug-induced parkinsonism [1.3.3, 1.6.5]. This condition involves symptoms like tremors, rigidity, and difficulty with movement. The risk is particularly pronounced in elderly patients and with long-term use [1.4.3, 1.4.4]. This adverse effect is linked to the drug's ability to interfere with dopamine systems in the brain [1.6.6].
- Drowsiness: As a sedating antihistamine, it can cause significant drowsiness, which impairs the ability to drive or operate heavy machinery [1.4.1, 1.4.3].
- Other Side Effects: Other common side effects include gastrointestinal discomfort, dry mouth, and weight gain [1.4.1, 1.4.2]. While many of these are transient, the potential for more severe neurological effects is a major red flag for regulators.
Comparison of Cinnarizine and FDA-Approved Alternatives
While Americans cannot access cinnarizine, several FDA-approved alternatives are available for treating motion sickness and vertigo. The choice often depends on the specific cause and severity of the symptoms.
| Feature | Cinnarizine (Not available in US) | Meclizine (Bonine, Dramamine) | Dimenhydrinate (Dramamine) | Scopolamine (Transderm Scop) |
|---|---|---|---|---|
| Mechanism | Antihistamine, Calcium Channel Blocker [1.6.5] | First-generation antihistamine [1.2.1] | Antihistamine [1.5.2] | Anticholinergic [1.5.4] |
| Primary Use | Motion sickness, Vertigo [1.6.4] | Motion sickness, Vertigo [1.5.2] | Motion sickness, Vertigo [1.5.2] | Motion sickness, Post-op nausea [1.5.1, 1.5.4] |
| Form | Oral tablets [1.6.4] | Oral tablets (OTC) [1.2.1] | Oral tablets (OTC) [1.5.2] | Transdermal patch (Prescription) [1.5.1] |
| Key Side Effects | Drowsiness, risk of parkinsonism [1.3.3, 1.4.1] | High sedation [1.2.1] | Drowsiness, dry mouth [1.2.1] | Dry mouth, blurred vision [1.5.1, 1.5.4] |
| Availability (US) | Not available [1.2.2] | Over-the-counter (OTC) [1.2.1] | Over-the-counter (OTC) [1.5.2] | Prescription only [1.5.4] |
The Risks of Procuring Unapproved Drugs
Given its unavailability in the US, some may be tempted to purchase cinnarizine online from international pharmacies. The FDA strongly warns against this practice. Products sold from unverified sources may be counterfeit, contaminated, or contain incorrect dosages [1.3.6]. Using a drug without a physician's oversight can be dangerous, especially a drug like cinnarizine, which has significant contraindications and potential drug interactions with alcohol, antidepressants, and other CNS depressants [1.4.4, 1.6.9].
Conclusion
Cinnarizine is not available in the US primarily because it has never obtained FDA approval [1.2.5]. The decision is multifaceted, stemming from its dual action as a calcium channel blocker and concerns over its safety profile, most notably the risk of causing drug-induced movement disorders similar to Parkinson's disease [1.2.1, 1.3.3]. While considered an effective medication for motion sickness and vertigo in many parts of the world, the regulatory and safety hurdles have prevented its entry into the American market. Patients in the US have access to several effective, FDA-approved alternatives like meclizine and dimenhydrinate for managing these conditions [1.2.1, 1.5.2].
For more information on the FDA's drug approval process, you can visit the U.S. Food and Drug Administration website.
