Brimonidine

On August 26, 2013, the U. S. Food and Drug Administration (FDA) approved brimonidine (Mirvaso®) topical gel, 0.33%* (Galderma Laboratories, Texas, USA) for the topical treatment of persistent facial erythema (redness) of rosacea in adults 18 years of age or older. It is not indicated for the treatment of inflammatory lesions (papules and pustules) of rosacea.

Although several medications are approved for the treatment of inflammatory rosacea, there is currently no approved medication directly targeting erythema of rosacea, making it a key unmet medical need.

Brimonidine is the first and only FDA-approved topical treatment specifically developed and indicated for facial erythema in rosacea.

Applied once daily, brimonidine works quickly to reduce the redness of rosacea and the beneficial effects last up to 12 hours.

Brimonidine is also available as eye drops to treat ocular hypertension or glaucoma.

How does brimonidine work?

• While the exact cause of erythema of rosacea is not known, it is hypothesized that erythema results from dysregulation in the cutaneous vasomotor responses, which leads to abnormal dilation of facial blood vessels upon various stimuli.
• Research studies suggest the involvement of adrenergic receptors in the neurovascular regulation pathway.
• Brimonidine is a relatively selective alpha-2 adrenergic agonist.
• Topical application of brimonidine gel may reduce erythema by constricting the dilated facial blood vessels to reduce the redness of rosacea.

Link to key clinical-trial evidence about brimonidine

Dosage and administration

• Brimonidine is supplied as a gel for topical administration.
• It is recommended that a pea-size amount of the drug is applied once daily to each of the five areas of the face: central forehead, chin, nose and each cheek.
• The gel should be applied smoothly and evenly as a thin layer across the entire face avoiding the eyes and lips.
• The gel should not be applied to irritated skin or open wounds.
• Hands need to be washed thoroughly after applying the topical gel.

What are the side effects of brimonidine?

In clinical trials, the most common adverse reactions (occurring at a frequency ≥1%) included:

• erythema
• flushing
• skin burning sensation
• contact dermatitis

In the long-term study, where patients used brimonidine topical gel for up to 12 months, the most common adverse events included flushing (10%), erythema (8%), rosacea (5%), nasopharyngitis (5%), skin burning sensation (4%), increased intraocular pressure (4%), and headache (4%).

Postmarketing reports suggest that rebound flare of redness and discomfort may be more common that was predicted by clinical trials.

Warnings and precautions

Worsening of vascular insufficiency

Brimonidine topical gel should be used with caution in patients with depression, cerebral or coronary insufficiency, Raynaud phenomenon, orthostatic hypotension, thrombangiitis obliterans, scleroderma/systemic sclerosis, or Sjögren syndrome.

Severe heart disease

Alpha-2 adrenergic agonists can lower blood pressure. Brimonidine topical gel should be used with caution in patients with severe or unstable or uncontrolled cardiovascular disease.

Serious adverse reactions after oral intake

Two young children experienced serious adverse reactions following accidental ingestion of brimonidine topical gel. Adverse reactions experienced included lethargy, respiratory distress with apnoeic episodes (requiring intubation), sinus bradycardia, confusion, psychomotor hyperactivity, and diaphoresis. Both children were hospitalized overnight and discharged the following day without sequelae.

Pregnancy

There are no adequate and well-controlled studies of the use of brimonidine topical gel in pregnant women. It is not known whether brimonidine is safe for breast feeding mothers. In animal studies, brimonidine tartrate has been shown to be excreted in breast milk.

Children

Safety and effectiveness in paediatric patients have not been studied.

The elderly

Clinical studies of brimonidine topical gel did not include sufficient numbers of subjects aged 65 years and over to determine whether they respond differently from younger subjects. One hundred and five subjects aged 65 years and older were included in clinical trials with brimonidine topical gel. No overall differences in safety or effectiveness were observed between subjects 65 years of age and younger adult subjects.

Drug interactions

Blood pressure and heart medication

Alpha-2 agonists, as a class, may reduce blood pressure. Patients on concomitant beta-blockers, anti-hypertensives and/or cardiac glycosides should be carefully monitored.

Central nervous system depressants

Although specific drug-drug interactions studies have not been conducted with brimonidine topical gel, the possibility of an additive or potentiating effect with CNS depressants (alcohol, barbiturates, opiates, sedatives, or anaesthetics) should be considered.

Monoamine oxidase inhibitors

Monoamine oxidase (MAO) inhibitors may theoretically interfere with the metabolism of brimonidine and potentially result in increased systemic side-effects such as hypotension.