Luvox CR and Tizanidine

In the database of official manuals used in the service creation an interaction registered by statistical results of studies was found, which can either lead to negative consequences for the patient health or strengthen a mutual positive effect. A doctor should be consulted to address the issue of joint drug administration.

Using fluvoxaMINE and tiZANidine is not recommended. Taking these drugs together can cause symptoms of drowsiness, dizziness, low blood pressure, slurred speech, confusion, or severe weakness. Avoid driving until you know how the medications will affect you. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

CONTRAINDICATED: Coadministration with fluvoxamine may significantly increase the plasma concentrations and pharmacologic effects of tizanidine. The proposed mechanism is fluvoxamine inhibition of tizanidine metabolism via CYP450 1A2. In 10 healthy volunteers, pretreatment with fluvoxamine (100 mg orally once daily for 4 days) increased the peak plasma concentration (Cmax) and systemic exposure (AUC) of tizanidine (4 mg single oral dose) by an average of 12- and 33-fold, respectively, compared to placebo. The mean elimination half-life of tizanidine was prolonged from 1.5 to 4.3 hours by fluvoxamine. Pharmacologic effects of tizanidine as measured by changes in blood pressure, heart rate, performance testing, subjective drug effect, and drowsiness were also significantly greater with fluvoxamine. Particularly alarming was the decrease in systolic blood pressure to a level of 80 mmHg or lower in some cases. The interaction was also suspected in a case report of a 70-year-old hospitalized patient who developed low heart rate, low body temperature, dry mouth, and anuresis during tizanidine administration two weeks after initiating fluvoxamine. A retrospective review of patient medical records at the hospital revealed a significantly higher incidence of tizanidine-related adverse effects in patients treated concomitantly with fluvoxamine than that reported for tizanidine alone in the product labeling (26.1% vs. 5.3%), and those who experienced adverse effects were older and received higher dosages of both drugs than those who did not have adverse effects with the combination.

MANAGEMENT: Given the magnitude of the interaction, use of tizanidine with fluvoxamine is considered contraindicated. Other SSRIs such as citalopram, escitalopram, fluoxetine, paroxetine, or sertraline may be safer alternatives in tizanidine-treated patients, since they are generally believed to have little, if any, effect on CYP450 1A2.

Luvox CR

Generic Name: fluvoxamine

Brand name: Luvox CR, Luvox

Synonyms: n.a.

What is Luvox CR?

Tizanidine

Generic Name: tizanidine

Brand name: Zanaflex

Synonyms: TiZANidine

What is Tizanidine?