ALLMERCAP

What it is

ALLMERCAP contains mercaptopurine monohydrate 50 mg in tablet form . Mercaptopurine monohydrate is an analogue of adenine and hypoxanthine that acts as an antimetabolite and interferes with the synthesis of nucleic acids in proliferating cells .

Approved indications

— Treatment of acute leukaemia — Remission induction in acute lymphoblastic leukaemia (ALL) and acute myelogenous leukaemia — Maintenance therapy in acute lymphoblastic leukaemia (ALL) and acute myelogenous leukaemia — Treatment of chronic granulocytic leukaemia

Dosing overview

For adults and children the usual dose is 2.5 mg/kg bodyweight per day, but the dose and duration of administration depend on the nature and dosage of other cytotoxic agents given in conjunction with ALLMERCAP . When allopurinol and mercaptopurine monohydrate are administered concomitantly it is essential that only a quarter of the usual dose of mercaptopurine monohydrate is given since allopurinol decreases the rate of catabolism of mercaptopurine monohydrate . In elderly patients it is advisable to monitor renal and hepatic function, and if there is any impairment, consideration should be given to reduce the ALLMERCAP dosage . Patients with little or no inherited TPMT activity are at increased risk for severe toxicity from conventional doses of mercaptopurine and generally require substantial dose reduction .

Key safety warnings

ALLMERCAP is strongly myelosuppressive and full blood counts must be monitored daily during remission induction, with complete blood counts including platelets performed weekly or more frequently during maintenance therapy if high dosage is used or if severe renal and hepatic disorder is present . Treatment with mercaptopurine monohydrate causes bone marrow suppression leading to leucopenia and thrombocytopenia, and less frequently anaemia . ALLMERCAP is hepatotoxic and liver function tests should be monitored weekly during treatment . The patient should be instructed to discontinue ALLMERCAP immediately if jaundice becomes apparent . There are individuals with an inherited deficiency of TPMT who may be unusually sensitive to the myelosuppressive effect of mercaptopurine monohydrate and prone to developing rapid bone marrow depression, and there have been fatal cases of myelosuppression in patients with low or absent TPMT activity treated with thiopurines . Patients should be tested for TPMT activity before starting ALLMERCAP . Patients with inherited mutated NUDT15 gene are at increased risk for severe thiopurine toxicity such as early leucopenia and alopecia from conventional doses of thiopurine therapy and generally require substantial dose reduction, with patients of Asian ethnicity particularly at risk . Patients treated with mercaptopurine monohydrate alone or in combination with other immunosuppressive agents have shown increased susceptibility to viral, fungal and bacterial infections, including severe or atypical infection and viral reactivation, with infectious disease complications potentially more severe in these patients than in non-treated patients .

Contraindications

ALLMERCAP is contraindicated in hypersensitivity to any component of the preparation . In view of the seriousness of the indications there are no other absolute contraindications .

PBS listing

ALLMERCAP oral suspension containing mercaptopurine monohydrate 20 mg per mL, 100 mL is listed on the PBS as one item with restricted access at an ex-manufacturer price of A$330.59 .

Regulatory history

ALLMERCAP oral liquid suspension 20 mg/mL was first listed on the ARTG on 16 June 2014 . The product information for the tablet formulation was first approved on 14 June 2019 .