Gilead has informed all healthcare professionals involved in the management of chronic hepatitis B on important renal safety information and recommendations in the current European Summary of Product Characteristics ( SPC ) for Viread ( Tenofovir disoproxil fumarate, tenofovir DF ).
There are limited data on the safety and efficacy of Viread in patients with impaired renal function. Therefore, Viread should only be used in patients with impaired renal function if the potential benefits of treatment are considered to outweigh the potential risks.
For patients with creatinine clearance of < 50 ml/min, adjustment in the dosing interval for Viread and restrictions should be noted:
moderate renal impairment ( creatinine clearance 30-49 ml/min ): one tablet every 48 hours;
severe renal impairment ( creatinine clearance < 30 ml/min ): use of Viread is not recommended. If however no alternative treatment is available, and the potential benefits outweigh the risk, Viread may be administered every 72-96 hours ( dosing twice a week ). For haemodialysis patients, Viread may be administered every 7 days following completion of a haemodialysis session.
Further recommendation and information on the safety concern
Viread is principally eliminated via the kidney. Renal failure, renal impairment, elevated creatinine, hypophosphataemia and proximal tubulopathy ( including Fanconi syndrome ) have been reported with the use of Viread in clinical practice;
Creatinine clearance should be calculated in all patients prior to initiating therapy with Viread;
Renal function ( creatinine clearance and serum phosphate ) should be monitored every four weeks during the first year and then at three month intervals. In patients at risk for renal impairment, including patients who have previously experienced renal events while receiving Adefovir dipivoxil, consideration should be given to more frequent monitoring of renal function;
If serum phosphate is less than 1.5 mg/dl ( 0.48 mmol/l ) or creatinine clearance is decreased to less than 50 ml/min in any patient receiving Viread, renal function should be re-evaluated within one week, including measurements of blood glucose, blood potassium and urine glucose concentrations. Consideration should also be given to interrupting treatment with Viread in patients with creatinine clearance decreased to less than 50 ml/min or decreases in serum phosphate to less than 1.0 mg/dl ( 0.32 mmol/l );
Viread should not be administered concurrently with Hepsera ( adefovir dipivoxil ) due to the increased risk of renal toxicity;
Use of Viread should be avoided with concurrent or recent use of a nephrotoxic medicinal product. If concomitant use of Viread and nephrotoxic agents is unavoidable, renal function should be monitored weekly.
Source: Medicines and Healthcare product Regulatory Agency MHRA, 2008