1.6. Cinnarizine
Scheduling proposal
The delegate considered an application from the Therapeutic Goods Administration (TGA) for the scheduling of cinnarizine, a new chemical entity (NCE) for a human therapeutic medicine.
Substance summary
Cinnarizine is a selective calcium channel antagonist that acts mainly as a vestibular sedative through inhibition of the calcium influx into the vestibular sensory cells. Cinnarizine thus acts predominantly on the peripheral vestibular system. Cinnarizine was discovered in 1955 and is used to treat vestibular disorders including motion sickness, tinnitus and Meniere’s disease.
Cinnarizine is used in a fixed dose combination product with dimenhydrinate and is intended for the short term treatment of vertigo in adults.
| Property | Cinnarizine |
|---|---|
| CAS number | 298-57-7 |
| Chemical structure |  |
| Molecular formula | C26H28N2 |
| Molecular weight | 368.5 g/mol |
| Chemical names | (E)-1-(Diphenylmethyl)-4-(3-phenylprop-2-enyl)piperazine |
Scheduling status
Cinnarizine is not specifically scheduled and is not captured by any entry in the Standard for the Uniform Scheduling of Medicines and Poisons (SUSMP) – the Poisons Standard that was in effect at the time the decision was made (Poisons Standard October 2017 (SUSMP No. 18)).
International regulations
Cinnarizine is not classified or marketed in Canada, New Zealand or the United States of America.
Cinnarizine is classified as a non-prescription medicine in the United Kingdom (UK) in 15 mg tablets.
Delegate’s consideration
The delegate decided to make a delegate-only decision. The Advisory Committee on Medicines Scheduling was not consulted.
The delegate considered the following in regards to this application for scheduling:
- Subsection 52E(1) of the Therapeutic Goods Act 1989;
- The Scheduling Policy Framework (2015) scheduling factors;
- The TGA evaluation report; and
- The new drug application.
The delegate noted that currently there are no issues of concern that require additional control other than by inclusion in Schedule 4.
Delegate’s final decision
The delegate has made a final decision to amend the Poisons Standard to include cinnarizine in Schedule 4, with an implementation date of 1 February 2018.
The delegate has decided that the wording for the schedule entry will be as follows:
Schedule 4 – New Entry
CINNARIZINE.
The delegate decided that the relevant matters under subsection 52E(1) of the Therapeutic Goods Act 1989are: (a) the risks and benefits of the use of a substance; (b) the purpose and the extent of use of a substance; (c) the toxicity of a substance; (d) the dosage, formulation, labelling, packaging and presentation of a substance; and (f) any other matters that the Secretary considers necessary to protect public health.
The delegate decided that the reasons for the final decision comprise the following:
- Cinnarizine is an NCE with no marketing experience in Australia.
- Long term use without doctor supervision, particularly by older patients for chronic conditions associated with vertigo, may be put at unacceptable risk of extrapyramidal adverse effects, particularly Parkinsonism, which may be irreversible.
- Cinnarizine should not be taken long term due to its potential side effects.
- Limiting pack size may reduce the likelihood of long term use.
- Cinnarizine has been submitted for use in combination with dimenhydrinate, an antihistamine that was available in both Schedule 2 and Schedule 3 products. However, it was withdrawn from the Australian Register of Therapeutic Goods in June 2017.
- Both actives in the proposed fixed dose combination are available without prescription in the UK. It is not yet clear if this combination is also available without prescription in the UK.
- Cinnarizine has been associated with extrapyramidal effects that are not predictable in severity or time of onset after starting cinnarizine but are more likely in the elderly and individuals taking long term treatments.
- There is concern that if cinnarizine were available without prescription that it may be taken long term, particularly by elderly people and put them at risk of extrapyramidal effects which may be permanent.
- It is being proposed at this stage that the fixed dose combination would be acceptable for short term use e.g. recommended maximum duration of use 4 weeks. It should not be made available without prescription in order to limit long term use. Limiting pack size may reduce the likelihood of chronic use with its increased risk of extrapyramidal side effects. It is considered that only pack sizes consistent with no more than 4 weeks continuous use will be approved.