Published: 8 June 2018

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Tenofovir Disoproxil – a Salty Tale

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Prescriber Update 39(2): 20
June 2018

Tenofovir disoproxil is indicated in New Zealand for the treatment of chronic hepatitis B and HIV (in combination with other antiretroviral agents) in adults and children aged 12 years and older¹ .

On 1 June 2018, PHARMAC switched sole supply from Viread (Gilead) to Tenofovir Disoproxil Teva.

The different brands of tenofovir disoproxil contain different salt forms of the same active chemical substance (Table 1), and the succinate salt form has a different molecular weight to the fumarate. However, the quantity of active ingredient in each of these medicines is the same (tenofovir disoproxil 245 mg). The different brands are clinically equivalent.

Table 1: Tenofovir disoproxil medicines currently approved in New Zealand, their salt forms and content and the tenofovir disproxil content

Medicine	Salt form and content (mg)		Tenofovir disoproxil content (mg)
Viread (Gilead)	tenofovir disoproxil fumarate	300.0	245
Tenofovir Disoproxil Teva	tenofovir disoproxil succinate	300.6	245
Tenofovir Disoproxil Mylan	tenofovir disoproxil maleate	300.0	245

Medsafe and PHARMAC have decided to link all products back to the active ingredient (tenofovir disoproxil 245 mg). This will clearly describe the different tenofovir disoproxil medicines, and avoid confusion if alternate salt forms (eg, phosphate) and medicine strengths are introduced to New Zealand in future. Products will either be identified as 245 mg tenofovir disoproxil or have a clear equivalency statement on the label.

From 1 June 2018, please write all prescriptions for the active chemical substance: tenofovir disoproxil 245 mg.

More information about this change is available on the PHARMAC website² .

References

1. Teva Pharma (New Zealand) Limited. 2018. Tenofovir disoproxil tablets (Teva) 245 mg New Zealand Data Sheet February 2018. URL: www.medsafe.govt.nz/profs/Datasheet/t/TenofovirDisoproxiltab.pdf (accessed 20 April 2018).
2. PHARMAC. 2018. Proposal to widen access and change the funded brand of tenofovir disoproxil and entecavir. URL: www.pharmac.govt.nz/news/consultation-2018-03-09-tenofovir-disoproxil-entecavir/ (accessed 20 April 2018).