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The Department of Health (DH) today (February 18) cautioned the public about the use of two drugs, terbutaline and methylene blue because of safety alerts from the United States (US) and Canada respectively.
Regarding terbutaline, the DH noted that the US Food and Drug Administration (FDA) warned against the use of terbutaline, either by injection or infusion beyond 48-72 hours, or by mouth, for the prevention or prolonged treatment of preterm labour in pregnant women because of potential serious heart problems and even fatalities.
Terbutaline has smooth muscle relaxation action. It uses include the prevention or treatment of narrowing of airways in asthma, bronchitis and emphysema besides obstetrically for the prevention or treatment of preterm labour.
The decision was based on FDA's review of adverse incidents and literature which suggested both the absence of evidence that the use of terbutaline to prevent preterm labour improved infant outcomes, and the occurrence of serious cardiac events, including maternal deaths, in pregnant patients. The FDA concluded that the risks outweighed any potential benefit to pregnant patients and their babies. As a follow-up, additional package warning against prolonged injection or infusion, or orally for expectant mothers with preterm labour is mandatory in the US.
In Hong Kong, there are 38 registered pharmaceutical products which contain terbutaline. So far, the DH has not received any adverse event reports concerning the use of the drug in pregnant mothers.
However, in view of FDA's action, the DH decided to issue a letter to inform doctors and pharmacists about the latest position in the US. They are also advised to report any side effect from the use of terbutaline.
The issue will be discussed in the coming meeting of the Registration Committee of the Pharmacy and Poisons Board.
The second alert is issued after the DH has come to learn that Health Canada warned about the risk of serotonin toxicity when methylene blue injectable is used in combination with serotonin reuptake inhibitors (SRIs). SRIs are prescription drugs used for the treatment of depression such as Fluoxetine, Paroxetine, Citalopram and Fluvoxamine.
There had been reports of patients on SRIs presented with agitation, diaphoresis or hypertonia accompanied by fever, tremor, hyperreflexia or clonus after the concomitant use of methylene blue injectable.
In view of the above, the Canadian health authority is working with the drug registration holders to update the drug prescription information to include the following -
a) serotonin toxicity has been reported when methylene blue was administered in patients who also received other drugs with serotonin reuptake inhibition properties; and
b) if drugs with serotonin reuptake inhibition properties are being taken, careful consideration needs to be given to stop them before methylene blue injectable use to allow a washout period equivalent to at least four to five half-lives.
In Hong Kong, Methylene Blue Injection (HK-59020) is a Canadian product, prescribed for the treatment of methemoglobinemia. Its registration company, Sino-Asia Pharmaceutical Supplies Ltd., will be updating the package insert in accordance with Canadian requirement.
Meanwhile, the DH has also issued a letter to inform doctors and pharmacists about the possible drug interaction.
While the DH will closely monitor the developments of the two drug matters, a department spokesman urged patients to consult their healthcare professionals if in doubt or feel unwell.
Ends/Friday, February 18, 2011
Issued at HKT 21:31
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