The table below shows the frequencies of the adverse reactions observed in more than 1% of the subjects (a) in 6 placebo-controlled domestic studies in which patients in the active-treatment arm received 20 mg of isosorbide mononitrate twice daily, and (b) in all studies in which patients received isosorbide mononitrate in a variety of regimens. In parentheses, the same table shows the frequencies with which these adverse reactions led to discontinuation of treatment. Overall, 11% of the patients who received isosorbide mononitrate in the six controlled U.S. studies discontinued treatment because of adverse reactions. Most of these discontinued because of headache. "Dizziness" and nausea were also frequently associated with withdrawal from these studies.
| Frequency of Adverse Reactions (Discontinuations)*
|| 6 Controlled Studies
|| 92 Clinical Studies
|| 20 mg
|| 9% (0%)
|| 38% (9%)
|| 19% (4.3%)
|| 1% (0%)
|| 5% (1%)
|| 3% (0.2%)
| Nausea, Vomiting
|| < 1% (0%)
|| 4% (3%)
|| 2% (0.2%)
| *Some individuals discontinued for multiple reasons.
Other adverse reactions, each reported by fewer than 1% of exposed patients, and in many cases of uncertain relation to drug treatment, were::
Cardiovascular: angina pectoris, arrhythmias, atrial fibrillation, hypotension,
palpitations, postural hypotension, premature ventricular contractions, supraventricular
Dermatologic: pruritus, rash.
Gastrointestinal: abdominal pain, diarrhea, dyspepsia, tenesmus, tooth
Genitourinary: dysuria, impotence, urinary frequency.
Miscellaneous: asthenia, blurred vision, cold sweat, diplopia, edema,
malaise, neck stiffness, rigors.
Neurological: agitation, anxiey, confusion, dyscoordination, hypoesthesia,
hypokinesia, increased appetite, insomnia, nervousness, nightmares.
Respiratory: bronchitis, pneumonia, upper-respiratory tract infection.
Extremely rarely, ordinary doses of organic nitrates have caused methemoglobinemia
in normal-seeming patients; for futher discussion of its diagnosis and treatment
see under OVERDOSAGE.
The vasodilating effects of isosorbide mononitrate may be additive with those of other vasodilators. Alcohol, in particular, has been found to exhibit additive effects of this variety. Marked symptomatic orthostatic hypotension has been reported when calcium channel blockers and organic nitrates were used in combination. Dose adjustments of either class of agents may be necessary.