Because clinical studies are conducted under widely varying conditions, adverse reaction rates observed in the clinical studies of a drug cannot be directly compared to rates in the clinical studies of another drug and may not reflect the rates observed in practice.

Adults: Incidence in Controlled Clinical Trials: Adverse reactions to rizatriptan benzoate were assessed in controlled clinical trials that included over 3,700 adult patients who received single or multiple doses of rizatriptan benzoate tablets. The most common adverse reactions during treatment with rizatriptan benzoate (≥ 5% in either treatment group and greater than placebo) were asthenia/fatigue, somnolence, pain/pressure sensation and dizziness. These adverse reactions appeared to be dose related.

Table 1 lists the adverse reactions (incidence ≥ 2% and greater than placebo) after a single dose of rizatriptan benzoate in adults.

Table 1: Incidence ( ≥2% and Greater than Placebo) of Adverse Reactions After a Single Dose of Rizatriptan Benzoate Tablets or Placebo in Adults

The frequencies of adverse reactions in clinical trials did not increase when up to three doses were taken within 24 hours. Adverse reaction frequencies were also unchanged by concomitant use of drugs commonly taken for migraine prophylaxis (including propranolol), oral contraceptives, or analgesics. The incidences of adverse reactions were not affected by age or gender. There were insufficient data to assess the impact of race on the incidence of adverse reactions.

Other Events Observed in Association with the Administration of Rizatriptan Benzoate in Adults:

In the following section, the frequencies of less commonly reported adverse events are presented that were not reported in other sections of the labeling. Because the reports include events observed in open studies, the role of rizatriptan benzoate in their causation cannot be reliably determined. Furthermore, variability associated with adverse event reporting, the terminology used to describe adverse events, limit the value of the quantitative frequency estimates provided. Event frequencies are calculated as the number of patients who used rizatriptan benzoate and reported an event divided by the total number of patients exposed to rizatriptan benzoate (n = 3,716). All reported events occurred at an incidence ≥ 1%, or are believed to be reasonably associated with the use of the drug. Events are further classified within body system categories and enumerated in order of decreasing frequency using the following definitions: frequent adverse events are those defined as those occurring in at least (>) 1/100 patients; infrequent adverse experiences are those occurring in 1/100 to 1/1,000 patients; and rare adverse experiences are those occurring in fewer than 1/1,000 patients.

General:Infrequent was facial edema. Rare were syncope and edema/swelling.

Atypical Sensations:Frequent were warm sensations.

Cardiovascular:Frequent was palpitation. Infrequent were tachycardia, cold extremities, and bradycardia.

Digestive:Frequent were diarrhea and vomiting. Infrequent were dyspepsia, tongue edema and abdominal distention.

Musculoskeletal:Infrequent were muscle weakness, stiffness, myalgia and muscle cramp/spasm.

Neurological/Psychiatric:Frequent were hypoesthesia, euphoria and tremor. Infrequent were vertigo, insomnia, confusion/disorientation, gait abnormality, memory impairment, and agitation.

Respiratory:Frequent was dyspnea. Infrequent was pharyngeal edema.

Special Senses:Infrequent were blurred vision and tinnitus. Rare was eye swelling.

Skin and Skin Appendage:Frequent was flushing. Infrequent were sweating, pruritus, rash, and urticaria. Rare was erythema, hot flashes.

The adverse reaction profile seen with rizatriptan benzoate orally disintegrating tablets was similar to that seen with rizatriptan benzoate tablets.

Pediatric Patients 6 to 17 Years of Age: Information relating to adverse reactions to rizatriptan benzoate orally disintegrating tablets in a controlled clinical trial in pediatric patients (6 to 17 years old) is approved for Merck & Co., Inc.’s Rizatriptan Benzoate Orally Disintegrating Tablets. However, due to Merck & Co., Inc.’s marketing exclusivity rights, this drug product is not labeled with that information.