These medicines are used to treat epilepsy, bipolar disorder, migraine headaches and other conditions.
Medsafe's alert follows a similar statement issued by the US Food and Drug Administration (FDA), which is posted on the Medsafe website
The warnings are based on studies showing that for every 1000 people taking these medicines, on average an additional two people will have suicidal thoughts or behaviours.
"We are providing doctors and health care professionals with the FDA's advice so they can inform patients and their families about the risk of suicidality as a result of taking these medicines," Medsafe's interim manager Dr Stewart Jessamine said.
"In the meantime, we advise patients to consult their doctor before making any changes to the medicines they're taking," he said.
"Alerting patients to this small additional risk means that they, and those caring for them, would be on the lookout for any unusual changes in behaviour or mood and then be able to talk to their healthcare provider."
Medsafe will be working with the companies distributing anti-epileptic medicines in New Zealand to ensure the information available to health professionals is up-to-date and includes the warning of risk of suicidality.
The FDA analysis of reports of suicidality showed that patients taking these medicines have about twice the risk of having suicidal thoughts and behaviours (0.43%) compared with patients given placebo (0.22%).
This means that in those groups taking these medicines an additional two (2.1) patients in every 1000 experienced suicidal thoughts than in those groups taking a harmless substitute (placebo).
Dr Jessamine said the FDA advisory would be discussed at the next meeting of the Medicines Adverse Reactions Committee (MARC) in March. MARC provides advice to the Minister of Health about medicine adverse reactions and advises on action that should be taken.
The anti-convulsant medicines approved for use in New Zealand are:
Phenobarbital (brand name Phenobarbitone)
Phenytoin sodium (brand name Dilantin)
Ethosuximide (brand name Zarontin)
Carbamazepine (brand names Tegretol, Tegretol CR, Teril)
Oxcarbazepine (brand name Trileptal)
Sodium valproate (brand name Epilim,)
Tiagabine (brand name Gabitril)
Vigabatrin (brand name Sabril)
Gabapentin (brand names Apo-Gabapentin, Arrow-Gabapentin, Neurontin, Nupentin)
Topiramate (brand names Apo-Topiramate, Topamax)
Lamotrigine (brand names Arrow-Lamotrigine, Lamictil, Lamitor DT, Logem, Mogine, Motrig)
Levetiracetam (brand name Keppra)
Pregabalin (brand name Lyrica)
Primidone (brand name Apo-Primidone)
Note: Medsafe is the Ministry of Health's drug regulatory arm, responsible for ensuring the appropriate level of safety and effectiveness of medicines used in New Zealand.
