Serious cardiac events, including some that have been fatal, have occurred following the use of 5-HT1 agonists. These events are extremely rare and most have been reported in patients with risk factors predictive of CAD. Events reported have included coronary artery vasospasm, transient myocardial ischemia, myocardial infarction, ventricular tachycardia, and ventricular fibrillation (see Contraindications; Cardiovascular under Precautions).
Clinical Trial Adverse Drug Reactions: Because clinical trials are conducted under very specific conditions the adverse reaction rates observed in the clinical trials may not reflect the rates observed in practice and should not be compared to the rates in the clinical trials of another drug. Adverse drug reaction information from clinical trials is useful for identifying drug-related adverse events and for approximating rates.
Experience in Controlled Clinical Trials with sumatriptan succinate: Typical 5-HT1 Agonist Adverse Reactions: As with other 5-HT1 agonists, sumatriptan succinate has been associated with sensations of heaviness, pressure, tightness or pain, which may be intense. These may occur in any part of the body including the chest, throat, neck, jaw and upper limb.
Acute Safety: In placebo-controlled migraine trials, 3095 patients received at least one dose of oral sumatriptan succinate. Table 7 lists adverse events occurring at an incidence of 1% or more in any of the sumatriptan succinate dose groups and that occurred at a higher incidence than in the placebo groups. (See Table 7.)
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Sumatriptan succinate is generally well tolerated. Most of the events were transient in nature and resolved within 2 hours of oral administration.
Other Events Observed During Clinical Trials: Minor disturbances of liver function tests have occasionally been observed with sumatriptan treatment. There is no evidence that clinically significant abnormalities occurred more frequently with sumatriptan than with placebo.
Dyspnea has commonly been observed following sumatriptan treatment.
Post-Market Adverse Drug Reactions: The following enumerates potentially important adverse events that have occurred in clinical practice and that have been reported spontaneously to various surveillance systems. The events enumerated represent reports arising from both domestic and nondomestic use of sumatriptan. These events do not include those already listed previously. Because the reports cite events reported spontaneously from worldwide postmarketing experience, the frequency of such events and the role of sumatriptan in their causation cannot be reliably determined.
Cardiac Disorders: Bradycardia, tachycardia, palpitations, cardiac arrhythmias, transient ischaemic ECG changes, coronary artery vasospasm, angina, myocardial infarction (see Contraindications; Cardiovascular under Precautions).
Ophthalmologic Disorders: Patients treated with sumatriptan succinate rarely exhibit visual disorders like flickering and diplopia. Additionally, cases of reduced vision have been observed. Very rarely, both transient and permanent loss of vision have occurred. These occurrences have included reports of retinal vascular occlusion, ocular venous thrombosis, vasospasm of the eye and ischemic optic neuropathy. Visual disorders may also occur during a migraine attack itself.
Gastrointestinal Disorders: Colonic ischemia (see Cardiovascular: Other Vasospasm-Related Events under Precautions).
Immune System Disorders: Hypersensitivity reactions ranging from cutaneous hypersensitivity to anaphylaxis (see Immune under Precautions).
Nervous System Disorders: Seizures, although some have occurred in patients with either a history of seizures or concurrent conditions predisposing to seizures there are also reports in patients where no such predisposing factors are apparent (see Neurologic: Seizures under Precautions).
There have been very rare reports of dystonia and related extrapyramidal disorders, such as choreoathetoid movement, akathisia, parkinsonism and akinesia following both subcutaneous and oral treatments of sumatriptan succinate. Patients with previous history of drug related dystonia and patients taking medications recognised to be associated with movement disorders such as SSRIs, may be at higher risk.
Vascular Disorders: Hypotension, Raynaud's phenomenon, peripheral vascular ischemia (see Contraindications; Cardiovascular: Other Vasospasm-Related Events and Increase in Blood Pressure under Precautions).