CYCLONEX

What it is

Cyclonex is a film-coated tablet formulation of cyclophosphamide monohydrate, with each tablet containing 50 mg of cyclophosphamide. Cyclophosphamide itself is not an alkylating agent but is converted by a series of reactions in the liver to its active form, which interferes with the growth of susceptible neoplasms and to a certain extent with normal tissue regeneration. Cyclophosphamide has important immunosuppressive properties.

Approved indications —

Frequently responsive myeloproliferative and lymphoproliferative disorders: malignant lymphomas (stages III and IV), multiple myeloma, leukaemias, and mycosis fungoides (advanced disease) — Frequently responsive solid malignancies: neuroblastoma (patients with disseminated disease), adenocarcinoma of the ovary, and retinoblastoma — Infrequently responsive malignancies: carcinoma of the breast and malignant neoplasm of the lung — Autoimmune diseases and immunopathies such as Wegener's granulomatosis when these diseases have been resistant to conventional first and second line treatment, and for the prevention of transplant rejection

Dosing overview

For induction therapy with no haematological deficiency, the usual initial intravenous loading dose is 40–50 mg/kg, typically given in divided doses over a period of two to five days. If initial therapy is given orally, a dose of 1–5 mg/kg/day can be administered depending on tolerance by the patient. For maintenance therapy, a variety of schedules have been used: 1–5 mg/kg orally daily; 10–15 mg/kg intravenous every 7 to 10 days; or 3–5 mg/kg intravenous twice weekly. For immunosuppressive therapy, doses used have been in the order of 1–3 mg/kg orally depending upon response and toxicity.

Key safety warnings

Sterile haemorrhagic cystitis is a severe adverse reaction that has been reported with cyclophosphamide therapy. To prevent this toxic effect, patients should be instructed to increase their fluid intake for a period of 24 hours before, during and at least 24 hours after receiving cyclophosphamide therapy, and should void frequently for 24 hours after receiving the drug. Frequent voiding helps prevent the development of cystitis, but when it occurs, it is necessary to interrupt cyclophosphamide therapy. One of the major toxicities of cyclophosphamide is bone marrow suppression. Leucopoenia and neutropenia (granulocytopenia) are expected to occur following therapeutic doses of the drug and they may be severe. Leucopoenia may occur with or without fever and carries the risk of secondary and potentially life-threatening infections. Since cyclophosphamide therapy has immunosuppressive activity that can potentially lead to serious or fatal infections, the patient should be carefully monitored for any sign or symptom of infection. Interruption or modification of dosage should be considered for patients who develop bacterial, fungal, protozoal, helminthic or viral infections. This is especially true for patients receiving or who have recently received concomitant steroid therapy since infections appear to be particularly dangerous under these circumstances. Some patients receiving cyclophosphamide have developed secondary malignancies, most frequently urinary bladder, myeloproliferative and lymphoproliferative malignancies. Secondary malignancies have occurred mainly in patients who have been treated with cyclophosphamide for primary haematological malignancies or primary non-malignant diseases in which immune processes are believed to be involved. In some cases, the secondary malignancy was not detected until several years after discontinuing cyclophosphamide therapy.

Contraindications

Cyclophosphamide is contraindicated in patients who have demonstrated a previous hypersensitivity to it. The presence of active infections, which may lead to fatal complications as a result of immunosuppression induced by the cytotoxic treatment, is a contraindication. Patients with evidence of cystitis, acute systemic or urinary infection, urinary outflow obstruction, drug or radiation-induced haemorrhagic cystitis should not receive this drug. Patients with severely depressed bone marrow function, particularly those who have been pre-treated with cytotoxic agents and/or radiotherapy, are contraindicated. Cyclophosphamide is contraindicated in the first trimester of pregnancy. Cyclophosphamide therapy should not be commenced for 4 to 8 days after major surgery.

PBS listing

Cyclonex 50 mg tablets are listed on the PBS with one item code. The listing is restricted, with an ex-manufacturer price of A$131.65, current as of 1 May 2026.

Regulatory history

Cyclonex was first approved on 14 April 2003. The ARTG registration for Cyclonex cyclophosphamide 50 mg tablet blister pack (ARTG 297901) was first listed on 28 March 2018 under licence category RE.