Isosorbide Mononitrate (Page 2 of 3)
INDICATIONS AND USAGE
Isosorbide mononitrate extended-release tablets, USP are indicated for the prevention of angina pectoris due to coronary artery disease. The onset of action of oral ISMN is not sufficiently rapid for this product to be useful in aborting an acute anginal episode.
Isosorbide mononitrate extended-release tablets are contraindicated in patients who have shown hypersensitivity or idiosyncratic reactions to other nitrates or nitrites.
Amplification of the vasodilatory effects of Isosorbide mononitrate extended-release tablets by sildenafil can result in severe hypotension. The time course and dose dependence of this interaction have not been studied. Appropriate supportive care has not been studied, but it seems reasonable to treat this as a nitrate overdose, with elevation of the extremities and with central volume expansion.
The benefits of ISMN in patients with acute myocardial infarction or congestive heart failure have not been established; because the effects of ISMN are difficult to terminate rapidly, this drug is not recommended in these settings. If ISMN is used in these conditions, careful clinical or hemodynamic monitoring must be used to avoid the hazards of hypotension and tachycardia.
Severe hypotension, particularly with upright posture, may occur with even small doses of ISMN. This drug should therefore be used with caution in patients who may be volume depleted or who, for whatever reason, are already hypotensive. Hypotension induced by ISMN may be accompanied by paradoxical bradycardia and increased angina pectoris.
Nitrate therapy may aggravate the angina caused by hypertrophic cardiomyopathy
In industrial workers who have had long term exposure to unknown (presumably high) doses of organic nitrates, tolerance clearly occurs. Chest pain, acute myocardial infarction, and even sudden death have occurred during temporary withdrawal of nitrates from these workers, demonstrating the existence of true physical dependence. The importance of these observations to the routine, clinical use of oral ISMN is not known.
Information for Patients
Patients should be told that the antianginal efficacy of Isosorbide mononitrate extended-release tablets can be maintained by carefully following the prescribed schedule of dosing. For most patients, this can be accomplished by taking the dose on arising.
As with other nitrates, daily headaches sometimes accompany treatment with ISMN. In patients who get these headaches, the headaches are a marker of the activity of the drug. Patients should resist the temptation to avoid headaches by altering the schedule of their treatment with ISMN, since loss of headache may be associated with simultaneous loss of antianginal efficacy. Aspirin or acetaminophen often successfully relieves ISMN induced headaches with no deleterious effect on ISMN’s antianginal efficacy. Treatment with ISMN may be associated with light-headedness on standing, especially just after rising from a recumbent or seated position. This effect may be more frequent in patients who have also consumed alcohol.
The vasodilating effects of ISMN 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.
DRUG / LABORATORY TEST INTERACTIONS
Nitrates and nitrites may interfere with the Zlatkis-Zak color reaction, causing falsely low readings in serum cholesterol determinations.
Carcinogenesis, Mutagenesis, Impairment of Fertility
No evidence of carcinogenicity was observed in rats exposed to Isosorbide Mononitrate (ISMN) in their diets at doses of up to 900 mg/kg/day for the first 6 months and 500 mg/kg/day for the remaining duration of a study in which males were dosed for up to 121 weeks and females were dosed for up to 137 weeks. No evidence of carcinogenicity was observed in mice exposed to isosorbide mononitrate in their diets for up to 104 weeks at doses of up to 900 mg/kg/day.
ISMN did not produce gene mutations (Ames test, mouse lymphoma test) or chromosome aberrations (human lymphocyte and mouse micronucleus tests) at biologically relevant concentrations. No effects on fertility were observed in a study in which male and female rats were administered doses of up to 750 mg/kg/day beginning, in males, 9 weeks prior to mating, and in females, 2 weeks prior to mating.
Pregnancy Category B
In studies designed to detect effects of ISMN on embryo-fetal development, doses of up to 240 or 248 mg/kg/day, administered to pregnant rats and rabbits, were unassociated with evidence of such effects. These animal doses are about 100 times the maximum recommended human dose (120 mg in a 50 kg woman) when comparison is based on body weight; when comparison is based on body surface area, the rat dose is about 17 times the human dose and the rabbit dose is about 38 times the human dose. There are, however, no adequate and well-controlled studies in pregnant women. Because animal reproduction studies are not always predictive of human response, Isosorbide mononitrate extended-release tablets should be used during pregnancy only if clearly needed.
Neonatal survival and development and incidence of stillbirths were adversely affected when pregnant rats were administered oral doses of 750 (but not 300) mg ISMN/kg/day during late gestation and lactation. This dose (about 312 times the human dose when comparison is based on body weight and 54 times the human dose when comparison is based on body surface area) was associated with decreases in maternal weight gain and motor activity and evidence of impaired lactation.
It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when ISMN is administered to a nursing mother.
The safety and effectiveness of ISMN in pediatric patients have not been established.
Clinical studies of Isosorbide Mononitrate Extended-release Tablets did not include sufficient information on patients age 65 and over to determine whether they respond differently from younger patients. Other reported clinical experience for Isosorbide Mononitrate Extended-release Tablets has not identified differences in response between elderly and younger patients. Clinical experience for organic nitrates reported in the literature identified a potential for severe hypotension and increased sensitivity to nitrates in the elderly. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.
Elderly patients may have reduced baroreceptor function and may develop severe orthostatic hypotension when vasodilators are used. Isosorbide Mononitrate Extended-release Tablets should therefore be used with caution in elderly patients who may be volume depleted, on multiple medications or who, for whatever reason, are already hypotensive. Hypotension induced by isosorbide mononitrate may be accompanied by paradoxical bradycardia and increased angina pectoris.
Elderly patients may be more susceptible to hypotension and may be at greater risk of falling at therapeutic doses of nitroglycerin.
Nitrate therapy may aggravate the angina caused by hypertrophic cardiomyopathy, particularly in the elderly.
The table below shows the frequencies of the adverse events that occurred in >5% of the subjects in three placebo-controlled North American studies, in which patients in the active treatment arm received 30 mg, 60 mg, 120 mg or 240 mg of ISMN as Isosorbide mononitrate extended-release tablets once daily. In parentheses, the same table shows the frequencies with which these adverse events were associated with the discontinuation of treatment. Overall, 8% of the patients who received 30 mg, 60 mg, 120 mg or 240 mg of ISMN in the three placebo-controlled North American studies discontinued treatment because of adverse events. Most of these discontinued because of headache. Dizziness was rarely associated with withdrawal from these studies. Since headache appears to be a dose-related adverse effect and tends to disappear with continued treatment, it is recommended that Isosorbide mononitrate extended-release tablets treatment be initiated at low doses for several days before being increased to desired levels.
|Three controlled North America Studies|
|Dose||Placebo||30 mg||60 mg||120 mg**||240 mg**|
|*Some individuals discontinued for multiple reasons|
|** Patients were started on 60 mg and titrated to their final dose|
In addition, the three North American trials were pooled with 11 controlled trials conducted in Europe. Among the 14 controlled trials, a total of 711 patients were randomized to Isosorbide mononitrate extended-release tablets. When the pooled data were reviewed, headache and dizziness were the only adverse events that were reported by >5% of patients. Other adverse events, each reported by ≤5% of exposed patients, and in many cases of uncertain relation to drug treatment, were:
Autonomic Nervous System Disorders: Dry mouth, hot flushes
Body as a Whole: Asthenia, back pain, chest pain, edema, fatigue, fever, flu-like symptoms, malaise, rigors.
Cardiovascular Disorders, General: Cardiac failure, hypertension, hypotension.
Central and Peripheral Nervous System Disorders: Dizziness, headache, hypoesthesia, migraine, neuritis, paresis, paresthesia, ptosis, tremor, vertigo.
Gastrointestinal System Disorders: Abdominal pain, constipation, diarrhea, dyspepsia, flatulence, gastric ulcer, gastritis, glossitis, hemorrhagic gastric ulcer, hemorrhoids, loose stools, melena, nausea, vomiting.
Hearing and Vestibular Disorders: Earache, tinnitus, tympanic membrane perforation.
Heart Rate and Rhythm Disorders: Arrhythmia, arrhythmia atrial, atrial fibrillation, bradycardia, bundle branch block, extrasystole, palpitation, tachycardia, ventricular tachycardia.
Liver and Biliary System Disorders: SGOT increase, SGPT increase.
Metabolic and Nutritional Disorders: Hyperuricemia, hypokalemia.
Musculoskeletal System Disorders: Arthralgia, frozen shoulder, muscle weakness, musculoskeletal pain, myalgia, myositis,tendon disorder, torticollis.
Myo-, Endo-, Pericardial and Valve Disorders: Angina pectoris aggravated, heart murmur, heart sound abnormal, myocardial infarction, Q-Wave abnormality.
Platelet, Bleeding and Clotting Disorders: Purpura, thrombocytopenia.
Psychiatric Disorders: Anxiety, concentration impaired, confusion, decreased libido, depression, impotence, insomnia, nervousness, paroniria, somnolenc
Red Blood Cell Disorder: Hypochromic anemiae.
Reproductive Disorders, Female: Atrophic vaginitis, breast pain.
Resistance Mechanism Disorders: Bacterial infection, moniliasis, viral infection.
Respiratory System Disorders: Bronchitis, bronchospasm, coughing, dyspnea, increased sputum, nasal congestion, pharyngitis, pneumonia, pulmonary infiltration, rales, rhinitis, sinusitis.
Skin and Appendages Disorders: Acne, hair texture abnormal, increased sweating, pruritus, rash, skin nodule.
Urinary System Disorders: Polyuria, renal calculus, urinary tract infection.
Vascular (Extracardiac) Disorders: Flushing, intermittent claudication, leg ulcer, varicose vein.
Vision Disorders: Conjunctivitis, photophobia, vision abnormal.
In addition, the following spontaneous adverse event has been reported during the marketing of Isosorbide Mononitrate (ISMN): syncope.
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