Other safety alerts
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| The United Kingdom: Posaconazole (Noxafil) - tablets and oral suspension are not directly interchangeable |
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The Medicines and Healthcare products Regulatory Agency (MHRA) advised that switching from posaconazole oral solution to tablets has resulted in cases of dose-related toxicity, whereas switching from tablets to oral solution has resulted in underdosing and lack of efficacy.
Posaconazole (Noxafil) is a broad-spectrum triazole antifungal for the treatment and prevention of fungal infections; and Posaconazole is available as an oral suspension (40 mg/mL), tablets (100 mg), and concentrate for solution for infusion (300 mg).
The MHRA advised healthcare professionals of the followings:
• posaconazole tablets and oral suspension are not directly interchangeable.
• switching from oral suspension to tablets can lead to overdosing and serious adverse drug reactions, whereas switching from tablets to oral suspension can lead to underdosing and lack of efficacy.
• prescribers should specify the dosage form for posaconazole on every prescription.
• pharmacists should ensure that the correct oral form is dispensed to patients.
In the UK, the MHRA was aware of 3 reports of medication errors related to substitutions of posaconazole tablets and oral suspension at the same dose. Two reports were patients prescribed posaconazole tablets but were dispensed the oral suspension; one patient developed an infection which may have been related to the underdose. The third patient was prescribed posaconazole oral suspension but was dispensed tablets, reporting headache and renal impairment.
Posaconazole tablets and oral suspension are not interchangeable because of differences between the two forms in dosing frequency, administration with food, and plasma drug levels achieved.
In the UK, the labelled oral dosage of posaconazole is:
• tablet: 300 mg/day (after a loading dose on day 1 of 600 mg/day)
• oral suspension: 600–800 mg/day
Product information for posaconazole is being updated to clarify that the oral solution cannot be directly substituted for the oral tablet, or vice versa, at the same dose. The outer cartons of the oral forms have also been revised to better distinguish the tablets from the oral suspension, and to include a warning statement that the products should not be substituted for one another without adjustment of the dose.
Please refer to the following website in MHRA for details:
http://www.gov.uk/drug-safety-update/posaconazole-noxafil-tablets-and-oral-suspension-are-not-directly-interchangeable
In Hong Kong, Noxafil Oral Susp 40mg/ml (HK-56439) is a pharmaceutical product registered by Merck Sharp & Dohme (Asia) Ltd, and is a prescription only medicine; while Noxafil tablet and concentrate for solution for infusion are not registered. Related news was previously issued by the US FDA and EMA, and was posted on the Drug Office website on 5 January and 25 June 2016 respectively. So far, the Department of Health (DH) has not received any adverse drug reaction report related to the product. As there is only one Noxafil oral formulation registered in Hong Kong, the MHRA announcement on tablets and oral suspension are not directly interchangeable does not have any impact on Hong Kong.
Ends/ Saturday, September 17, 2016
Issued at HKT 12:30
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