6.1 Clinical Trials Experience
Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. The adverse reaction information from clinical trials does, however, provide a basis for identifying the adverse events that appear to be related to drug use and for approximating rates.
Myocardial Infarction
These adverse reactions were reported from treatment regimens where intravenous metoprolol tartrate was administered, when tolerated.
Central Nervous System: Tiredness has been reported in about 1 of 100 patients. Vertigo, sleep disturbances, hallucinations, headache, dizziness, visual disturbances, confusion, and reduced libido have also been reported, but a drug relationship is not clear.
Cardiovascular: In a randomized comparison of metoprolol tartrate and placebo, the following adverse reactions were reported:
| Metoprolol Tartrate | Placebo |
|---|
| Hypotension (systolic BP <90 mmHg) | 27.4% | 23.2% |
| Bradycardia (heart rate <40 beats/min) | 15.9% | 6.7% |
| Second- or third-degree heart block | 4.7% | 4.7% |
| First-degree heart block (P-R ≥0.26 sec) | 5.3% | 1.9% |
| Heart failure | 27.5% | 29.6% |
Respiratory: Dyspnea of pulmonary origin has been reported in fewer than 1 of 100 patients.
Gastrointestinal: Nausea and abdominal pain have been reported in fewer than 1 of 100 patients.
Miscellaneous: Unstable diabetes and claudication have been reported.
6.2 Post-Marketing Experience
The following adverse reactions have been identified during post-approval use of metoprolol. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.
Cardiovascular: Cold extremities, arterial insufficiency (usually of the Raynaud type), palpitations, peripheral edema, syncope, and hypotension.
Respiratory: Wheezing (bronchospasm), dyspnea.
Central Nervous System: Confusion, short-term memory loss, headache, nightmares, insomnia, nervousness, hallucinations.
Gastrointestinal: Nausea, dry mouth, constipation, flatulence, heartburn, hepatitis, vomiting.
Hypersensitive Reactions: Pruritus.
Miscellaneous: Musculoskeletal pain, arthritis, blurred vision, decreased libido, tinnitus, reversible alopecia, agranulocytosis, dry eyes, worsening of psoriasis, Peyronie's disease, photosensitivity.
