October 2020

New Products

• Gemtuzumab ozogamicin (Mylotarg) is an antibody-drug conjugate (ADC) composed of the CD33‑directed monoclonal antibody (hP67.6; recombinant humanised IgG4κ) that is covalently linked to the cytotoxic agent, N-acetyl gamma calicheamicin. The antibody portion (hP67.6) binds specifically to the CD33 antigen, a sialic acid-dependent adhesion protein found on the surface of myeloid leukaemic blasts and immature normal cells of myelomonocytic lineage, but not on normal haematopoietic stem cells. The anticancer activity of gemtuzumab ozogamicin may be due to the binding of the ADC to CD33-expressing tumour cells, followed by internalisation of the ADC‑CD33 complex, and the intracellular release of N-acetyl gamma calicheamicin dimethyl hydrazide via hydrolytic cleavage of the linker. Activation of N-acetyl gamma calicheamicin dimethyl hydrazide induces double-stranded DNA breaks, subsequently inducing cell cycle arrest and apoptotic cell death. Mylotarg, in combination with standard anthracycline and cytarabine, is indicated for the treatment of patients ≥ 15 years with previously untreated, de novo CD33‑positive acute myeloid leukaemia, except acute promyelocytic leukaemia. Mylotarg powder for injection contains gemtuzumab ozogamicin 5 mg per vial and is available in pack size of 1.
   
• Midodrine hydrochloride (Vasodrine) is the rapidly absorbed prodrug of desglymidodrine. Desglymidodrine is a sympathomimetic agent with a direct and selective effect on peripheral α₁‑adrenergic receptors. This α₁‑stimulative effect induces vasoconstriction of the venous system (causing a reduction in venous pooling) and increases the peripheral arterial resistance, resulting in an increase in arterial blood pressure. Nonclinical experiments showed that midodrine had a selective effect on blood flow in various vascular beds, with the most effect observed in the femoral artery, and least in the mesenteric artery. Vasodrine is indicated for the treatment of adults with severe symptomatic orthostatic hypotension due to autonomic dysfunction when exacerbating factors have been addressed and other forms of treatment remain inadequate. Vasodrine is contraindicated in patients with severe organic heart disease (e.g. bradycardia, heart attack, congestive heart failure, cardiac conduction disturbances or aortic aneurysm); hypertension; serious obliterative blood vessel disease; cerebrovascular occlusions and vessel spasms; acute kidney disease; severe renal impairment (ClCr < 30 mL/min); serious prostate disorder; urinary retention; proliferative diabetic retinopathy; phaeochromocytoma; hyperthyroidism or thyrotoxicosis; and narrow angle glaucoma. Vasodrine tablets contain midodrine hydrochloride 2.5 mg or 5 mg and are available in a pack size of 90.

New Contraindications

• Colchicine (Colgout) is now contraindicated in patients with renal or hepatic impairment who are taking a P-glycoprotein inhibitor or strong CYP3A4 inhibitor.
   
• Dapoxetine (Priligy) is now contraindicated in patients with a history of syncope, mania or severe depression.
   
• Lercanidipine HCl (Zanidip) is now contraindicated in patients with left ventricular outflow tract obstruction; untreated congestive cardiac failure; unstable angina pectoris or recent myocardial infarction (within 1 month); severe renal impairment (GFR < 30 mL/min) including patients undergoing dialysis; and coadministration with strong CYP3A4 inhibitors, grapefruit or grapefruit juice.
   
• Linagliptin/metformin HCl (Trajentamet) is now contraindicated in patients with severe renal failure (ClCr < 30 mL/min), which may also result from conditions such as cardiovascular collapse (shock), acute myocardial infarction, and septicaemia.
   
• Telmisartan/hydrochlorothiazide (Micardis Plus) is now contraindicated in patients with coma hepaticum, hepatic precoma; acute glomerulonephritis; therapy-refractory hyponatraemia; hypovolaemia; and symptomatic hyperuricaemia or gout.
   
• Terlipressin (acetate) (Glypressin) is now contraindicated in patients with current or recent ischaemic cardiovascular disease.

This list is a summary of only some of the changes that have occurred over the last month.
Before prescribing, always refer to the full product information.

Revised opioids PBS listings from 1 October 2020

Commencing 1 October 2020, opioid listings on the Pharmaceutical Benefits Scheme (PBS) will be revised to ensure unimpeded access to opioid medication to palliative care patients, and to reduce additional administrative burden.

For more information, see https://www.pbs.gov.au/info/news/2020/09/revised-opioids-pbs-listings-from-1-october-2020.