Dimethyl Fumarate

Introduction Overview

Generic Name

dimethyl fumarate

Brand Name

Tecfidera

Dosage Form

delayed-release capsules (120 mg, 240 mg)

Drug Class

Selective immunosuppressants

Pharmacokinetics

Absorption:
Dimethyl fumarate (DMF), the active constituent of Tecfidera, is rapidly absorbed following oral administration of delayed-release capsules. After ingestion, DMF passes through the gastrointestinal tract, where it is rapidly hydrolyzed by esterases in the small intestine to its primary active metabolite, monomethyl fumarate (MMF). MMF reaches peak plasma concentrations approximately 2 to 2.5 hours post-dose under fasting conditions. Food intake can delay the time to peak concentration (Tmax) but does not significantly affect the overall extent of absorption (area under the curve, AUC). The delayed-release formulation protects DMF from premature degradation in the stomach, optimizing delivery to the small intestine and enhancing bioavailability.

Distribution:
After absorption and metabolism to MMF, distribution is characterized by its moderate plasma protein binding (approximately 27–40%), primarily to albumin. MMF is distributed systemically, including penetration into tissues such as the central nervous system (CNS), which is important for its effect in multiple sclerosis. The volume of distribution (Vd) indicates limited extensive tissue binding, consistent with its systemic immunomodulatory effects. MMF does not accumulate significantly in tissues with repeated dosing due to its relatively short half-life.

Metabolism:
DMF undergoes rapid and extensive presystemic hydrolysis primarily by esterases in the gut mucosa and blood, converting it almost completely to MMF, which is the active moiety. MMF itself is further metabolized via the tricarboxylic acid (TCA) cycle (Krebs cycle), eventually breaking down into carbon dioxide and water, which are excreted biologically. There is minimal involvement of cytochrome P450 enzymes, making significant drug-drug interactions via metabolic pathways unlikely. This metabolism pathway underscores a favorable pharmacokinetic profile.

Elimination:
Following systemic metabolism, MMF and its downstream metabolites are eliminated primarily via exhalation as carbon dioxide through the lungs. Less than 1% of the administered dose is excreted unchanged in the urine or feces. The elimination half-life of MMF is approximately 1 hour, which supports twice-daily dosing. The rapid clearance and metabolism of the drug reduce risks of accumulation and toxicity but necessitate adherence to dosing schedules to maintain therapeutic levels. Renal or hepatic impairment does not substantially affect elimination due to the non-renal and non-hepatic excretion routes.

Dosage Forms

Available Dosage Forms:
Tecfidera is supplied as delayed-release oral capsules designed to ensure targeted release in the small intestine, minimizing gastric irritation. The capsules are available in two strengths:
- 120 mg delayed-release capsule
- 240 mg delayed-release capsule

Each capsule contains dimethyl fumarate as the active ingredient, with inactive ingredients including microcrystalline cellulose, silicified microcrystalline cellulose, croscarmellose sodium, talc, silica colloidal silicon dioxide, magnesium stearate, triethyl citrate, methacrylic acid copolymers, simethicone emulsion, sodium lauryl sulphate, and polysorbate 80. The capsule shell contains gelatin, titanium dioxide, FD&C Blue 1, brilliant blue FCF, yellow and black iron oxides.

Dosages for Adults and Adolescents:
Tecfidera is FDA-approved for adult patients with relapsing forms of multiple sclerosis (MS). The recommended initial dosing regimen starts with 120 mg taken orally twice daily for the first 7 days to mitigate adverse effects. After this, the maintenance dose is increased to 240 mg orally twice daily. This dose is continued as long as the patient experiences clinical benefit without intolerable side effects. Tecfidera is not approved for use in patients under 18 years of age due to limited safety and efficacy data.

Specific Patient Populations:
- Renal and Hepatic Impairment: No dose adjustments are necessary as elimination is primarily metabolic and via exhalation.
- Pregnancy: There is insufficient human data; use only if clearly needed, after weighing risks against benefits.
- Elderly: Limited studies; no specific dose adjustments recommended, but cautious use is advised due to potential comorbidities.
- Pediatrics: Not approved.
- Patients with infections or low white blood cell counts should be closely monitored; therapy may require adjustment based on tolerability and blood test results.

Patient counseling should emphasize swallowing capsules whole without crushing, chewing, or opening to preserve delayed-release properties and minimize gastrointestinal irritation.

Mechanism Of Action

Tecfidera’s primary mechanism of action stems from its active metabolite, monomethyl fumarate (MMF). MMF modulates cellular pathways that affect inflammatory and oxidative stress responses, which are critical in the pathogenesis of multiple sclerosis (MS).

At the molecular level, MMF activates the nuclear factor (erythroid-derived 2)-like 2 (Nrf2) pathway. Nrf2 is a transcription factor that, when activated, translocates to the nucleus and induces the expression of various antioxidant response element (ARE)-driven genes. These genes encode for antioxidant proteins and detoxifying enzymes that enhance cellular defense against oxidative stress, a significant contributor to neural damage in MS lesions. Activation of Nrf2 leads to a reduction in reactive oxygen species (ROS) and mitigates inflammation-associated damage to myelin sheaths.

Additionally, MMF modulates immune responses through interaction with hydroxycarboxylic acid receptor 2 (HCAR2), a G-protein-coupled receptor expressed on various immune cells, including microglia and macrophages in the CNS. Activation of HCAR2 by MMF leads to anti-inflammatory effects by inhibiting NF-κB signaling pathways, reducing the release of pro-inflammatory cytokines, and promoting an anti-inflammatory microglial phenotype. This dual immunomodulatory and neuroprotective action is central to the clinical efficacy of Tecfidera.

Clinically, Tecfidera’s mechanisms reduce the frequency of MS relapses, delay progression of disability, and decrease the number of brain lesions detected by MRI. Compared with other MS drugs, such as interferon-beta or glatiramer acetate, which primarily modulate immune responses, Tecfidera provides additional antioxidant protection, which may confer enhanced neuroprotection. Recent clinical studies support the sustained activation of Nrf2 and downstream antioxidant pathways as a key factor in the drug’s therapeutic profile.

Overall, the combination of antioxidant and immune-modulating effects underpins Tecfidera's role as a selective immunosuppressant that attenuates the autoimmune attack on CNS myelin while protecting neurons from oxidative damage.

Pharmacological Actions

Selective immunosuppressant activity targeting inflammatory pathways involved in multiple sclerosis.
Activation of Nrf2 pathway leading to enhanced antioxidant defense and reduction of oxidative stress in neural tissues.
Modulation of immune cell function through HCAR2 receptor activation, promoting anti-inflammatory effects.
Inhibition of pro-inflammatory cytokine release via NF-κB pathway suppression.
Neuroprotective action by reducing demyelination and axonal damage.
Reduction in relapse rate and slowing progression of disability in relapsing forms of MS.
Improves MRI markers by decreasing new or enlarging brain lesions.
Minimal cytochrome P450 interaction potential, leading to a favorable drug interaction profile.
Oral administration facilitating patient compliance compared to injectable disease-modifying therapies.
Dose-dependent immunomodulation with initial titration to improve tolerability.
Delayed-release formulation to reduce gastrointestinal adverse effects.
Reduction of lymphocyte counts, contributing to immunosuppression but requiring monitoring.
Anti-inflammatory effects mediated through microglial modulation.
Impact on cellular metabolism through modulation of the tricarboxylic acid cycle intermediates.
Potential to reduce neurodegenerative progression by protecting CNS tissues from oxidative and immune-mediated damage.

Therapeutic Or Clinical Uses

Treatment of relapsing forms of multiple sclerosis (MS) in adults.
Reduction of relapse frequency in relapsing-remitting MS.
Delay of progression of physical disability associated with MS.
Reduction in the development of new or enlarging brain lesions detectable by MRI.
Management of clinically isolated syndrome suggestive of MS.
Treatment of active secondary progressive MS with relapses.
Alternative oral disease-modifying therapy for patients intolerant to injectables.
Adjunct therapy to reduce neurologic inflammation and demyelination processes.
Use in patients requiring long-term immunomodulation with manageable safety profiles.
Therapy option for patients seeking oral treatment with improved quality of life.
Employed to modulate immune response while minimizing broad immunosuppression.
Applicable in patients with inadequate response or contraindications to interferons.
Clinical utility supported by long-term studies demonstrating sustained efficacy.
FDA-approved indication based on pivotal clinical trial data confirming benefit-risk balance.
Treatment option balancing efficacy with generally manageable side effect profile.

Side Or Adverse Effects

Flushing: frequent side effect characterized by warmth, redness, itching, and burning sensations, affecting approximately 40% of patients.
Gastrointestinal disturbances including nausea, vomiting, diarrhea, abdominal pain, and dyspepsia, mostly occurring in the initial treatment period.
Rash, redness, and pruritus associated with mild hypersensitivity reactions.
Serious allergic reactions including anaphylaxis and angioedema, though rare.
Risk of infections including herpes zoster and other opportunistic viral or fungal infections due to immunosuppressive effects.
Progressive multifocal leukoencephalopathy (PML), a rare but serious brain infection potentially leading to disability or death.
Lymphopenia due to reductions in circulating lymphocytes, necessitating regular monitoring.
Hepatic dysfunction presenting as elevated liver enzymes, jaundice, or symptoms of liver injury.
Gastrointestinal bleeding, ulcers, or perforation have been rarely reported; require immediate medical attention.
Potential for flushing symptoms to cause patient discomfort and possible medication discontinuation.
Occasional reports of headache, fatigue, and upper respiratory tract infections.
Laboratory abnormalities including eosinophilia and increase in liver transaminases.
Very low incidence of severe hypersensitivity skin reactions.
Weight changes not consistently observed but anecdotal reports of gain or loss exist.
Injection site reactions are not applicable due to oral delivery but systemic reactions can occur.

Precautions

Monitor complete blood counts regularly to detect lymphopenia or low white blood cell counts.
Assess patients for active infections prior to and during therapy due to immunosuppressive properties.
Initiate therapy cautiously in patients with known immunodeficiency or history of recurrent infections.
Consider gradual dose titration to minimize flushing and gastrointestinal adverse effects.
Advise patients to take capsules with food to decrease flushing incidence and improve tolerability.
Avoid abrupt discontinuation without consulting healthcare provider due to risk of disease progression.
Pregnancy: use only if the potential benefit justifies potential risks; enroll pregnant patients in registries if possible.
Caution in breastfeeding women due to unknown excretion in breast milk.
Advise patients to avoid crushing, breaking, or opening capsules to prevent GI irritation.
Evaluate liver function tests during treatment and monitor for signs of hepatic injury.
Avoid use in pediatric patients as safety and efficacy have not been established.
Use cautiously in patients with pre-existing gastrointestinal disorders.
Regular neurological assessments to detect early signs of PML or other CNS adverse events.
Educate patients about symptoms of serious infections, liver problems, and GI complications.
Patients should inform their healthcare providers about all concomitant medications to avoid interactions.

Warnings

Serious risk of progressive multifocal leukoencephalopathy (PML), a potentially fatal viral brain infection.
Potential for serious allergic or hypersensitivity reactions including anaphylaxis.
Risk of lymphopenia leading to increased susceptibility to infections.
Severe gastrointestinal adverse events including bleeding, ulcers, and perforation have been reported.
Monitor for herpes virus infections and other opportunistic infections during treatment.
Discontinue or withhold therapy in patients developing significant infections or severe lymphopenia.
Increased liver enzymes and potential for hepatic injury necessitating periodic monitoring.
Not approved for use in pediatric patients under 18 years due to lack of safety data.
Risk of immune suppression requiring vigilance for emerging infections or malignancies.
Potential for worsening of MS symptoms if treatment is stopped abruptly without alternative therapy.
Avoid concomitant immunosuppressant therapies unless closely monitored.
Risk of severe flushing reactions leading to treatment discontinuation in some patients.
Pregnancy and lactation safety not established; use caution and counsel accordingly.
Possible increased risk of malignancies with long-term immunosuppression remains to be fully characterized.
Alcohol consumption should be limited to avoid compounding gastrointestinal irritation.

Contraindication

Known hypersensitivity to dimethyl fumarate, diroximel fumarate, or any inactive ingredients in Tecfidera.
History of severe allergic or anaphylactic reactions to fumarate compounds.
Use contraindicated in patients with active serious infections that compromise immune function.
Not approved for use in pediatric patients younger than 18 years old.
Concomitant use with other potent immunosuppressive therapies unless clinically justified.
Patients with pre-existing severe gastrointestinal disorders prone to bleeding or perforation.
Known or suspected hypersensitivity to gelatin or dye components of the capsule shell.
Contraindicated in patients with severe lymphopenia at baseline prior to initiation.
Avoid use in patients with progressive multifocal leukoencephalopathy or prior history of.
Contraindicated in patients with significant hepatic impairment without careful monitoring.
Cases of hypersensitivity to methacrylic acid copolymers or other excipients may preclude use.
Contraindications to aspirin pre-medication should be considered due to flushing management.
Should not be used if the patient has a history of intolerance to oral fumarates.
Contraindicated if patient has a hypersensitivity to excipients such as magnesium stearate or talc.
Avoid in individuals with contraindications to immunosuppressive medications generally.

Drug Interactions

Minimal cytochrome P450 mediated drug interactions due to predominant esterase metabolism.
Potential additive immunosuppression when used with other immunosuppressive or immunomodulatory agents.
Concomitant use with aspirin can reduce flushing symptoms by inhibiting prostaglandin synthesis.
No significant pharmacokinetic interactions observed with common MS therapies; however, caution advised.
Interactions with oral contraceptives or hormonal therapies have not been reported but monitoring suggested.
No known significant interactions with common over-the-counter medications or supplements.
Concomitant alcohol use may exacerbate gastrointestinal side effects and should be minimized.
Use with caution alongside other hepatotoxic drugs due to potential additive liver injury.
Potential interaction with herbal supplements that modulate immune function requires caution.
No significant interactions reported with vitamin supplements, though patient monitoring encouraged.
Drug interaction profiles suggest safety in combination with beta-interferons and glatiramer acetate.
Avoid concomitant use with agents known to cause lymphopenia or pancytopenia unless monitored.
No significant effect on renal transporter proteins or drug elimination mechanisms observed.
No known interaction with commonly used antibiotics or antivirals, yet clinical vigilance advised.
Incompatibility with drugs affecting prostaglandin pathways influencing flushing symptoms noted.

Preparations Of The Drug

Tecfidera is formulated as delayed-release capsules to protect the active ingredient and reduce gastric irritation.
Available strengths are 120 mg and 240 mg capsules, facilitating dose titration and maintenance therapy.
Capsule shell comprises gelatin, titanium dioxide, and colorants such as FD&C Blue 1 and iron oxides for identification.
Inactive ingredients include microcrystalline cellulose, silicified microcrystalline cellulose, croscarmellose sodium, talc, silica colloidal silicon dioxide, magnesium stearate, triethyl citrate, methacrylic acid copolymers, simethicone emulsion, sodium lauryl sulphate, and polysorbate 80, ensuring stability and bioavailability.
Designed for oral administration with delayed-release properties to optimize release in the small intestine.
Manufactured under strict quality control by Biogen Inc., Cambridge, MA, ensuring consistency and compliance with regulatory standards.
Stored at controlled room temperature (15°C to 30°C) in original moisture-protective containers to maintain drug integrity.
Packaging includes child-resistant bottles with desiccants to maintain capsule dryness and prevent degradation.
Contains no preservatives or lactose, reducing allergies related to excipients.
Manufactured to meet FDA-approved specifications and undergoes continual stability testing.
Prepared in single-entity capsule form without combination with other drugs.
Capsules are to be swallowed whole without crushing or chewing to preserve modified-release characteristics.
Stable under recommended storage conditions with shelf life consistent with label claims.
Not recommended for reformulation or compounding due to specialized delayed-release design.
Patient instructions accompany packaging to ensure proper administration and adherence.