DIMETHYL

What it is

DIMETHYL is a medicine containing dimethyl fumarate, available in delayed release capsules in two strengths: 120 mg and 240 mg.

Approved indications

— Relapsing multiple sclerosis, to reduce the frequency of relapses and to delay the progression of disability.

Dosing overview

The starting dose is 120 mg twice a day orally. After 7 days, the dose is increased to the recommended dose of 240 mg twice a day orally. Temporary dose reduction to 120 mg twice a day may reduce the occurrence of flushing and gastrointestinal side effects, and the recommended dose of 240 mg twice a day should be resumed within 1 month. The capsule or its contents should not be crushed, divided or dissolved as the enteric coating of the microtablets prevents irritant effects on the gut.

Key safety warnings

Due to the risk of serious, possibly fatal infection associated with lymphopenia, patients who develop lymphopenia require close monitoring and should be instructed to report symptoms of infection to their physician. Mean lymphocyte counts decreased by approximately 30% during the first year of treatment and then remained stable, with WBC counts less than 3.0 x 10⁹/L and lymphocyte counts less than 0.5 x 10⁹/L reported in 6 to 7% of subjects. A recent complete blood count including lymphocytes is recommended prior to initiating treatment, after 6 months of treatment, and every 6 to 12 months thereafter. Progressive multifocal leukoencephalopathy has occurred in the setting of lymphopenia in patients treated with DIMETHYL, predominantly in the setting of prolonged moderate to severe lymphopenia. Progressive multifocal leukoencephalopathy is an opportunistic viral infection of the brain that may lead to death or severe disability, with symptoms that may be similar to a multiple sclerosis relapse and include progressive weakness, disturbance of vision, and changes in thinking, memory, and orientation. Cases of anaphylaxis have been reported following DIMETHYL administration, generally occurring after the first dose but potentially at any time during treatment, and may be serious and life threatening. Serious cases of herpes zoster have occurred with DIMETHYL, including disseminated herpes zoster, herpes zoster ophthalmicus, herpes zoster meningoencephalitis and herpes zoster meningomyelitis, which may occur at any time during treatment. Serious gastrointestinal reactions, including perforation, ulceration, haemorrhage, and obstruction, some with fatal outcomes, have been reported in the post-marketing setting with fumaric acid esters including dimethyl fumarate, with the majority of these events occurring within 6 months of treatment initiation.

Contraindications

DIMETHYL is contraindicated in patients with known hypersensitivity to dimethyl fumarate or any excipients in this product.

Regulatory history

DIMETHYL was first listed on the ARTG on 17 November 2021 in two strengths: 120 mg and 240 mg modified release capsules.