In general, the incidence of adverse reactions correlates with the dose and duration of metoclopramide administration. The following reactions have been reported, although in most instances, data do not permit an estimate of frequency.
Restlessness, drowsiness, fatigue and lassitude may occur in patients receiving the recommended prescribed dosage of metoclopramide injection. Insomnia, headache, confusion, dizziness, or mental depression with suicidal ideation also may occur (see WARNINGS). In cancer chemotherapy patients being treated with 1 to 2 mg/kg per dose, incidence of drowsiness is about 70%. There are isolated reports of convulsive seizures without a clear-cut relationship to metoclopramide. Rarely, hallucinations have been reported.
Extrapyramidal Reactions (EPS)
Acute dystonic reactions, the most common type of EPS associated with metoclopramide, occur in approximately 0.2% of patients (1 in 500) treated with 30 to 40 mg of metoclopramide per day. In cancer chemotherapy patients receiving 1 to 2 mg/kg per dose, the incidence is 2% in patients over the ages of 30 to 35, and 25% or higher in pediatric patients and adult patients less than 30 years of age who have not had prophylactic administration of diphenhydramine. Symptoms include involuntary movements of limbs, facial grimacing, torticollis, oculogyric crisis, rhythmic protrusion of tongue, bulbar type of speech, trismus, opisthotonus (tetanus-like reactions) and rarely, stridor and dyspnea, possibly due to laryngospasm; ordinarily these symptoms are readily reversed by diphenhydramine (see WARNINGS).
Parkinsonian-like symptoms may include bradykinesia, tremor, cogwheel rigidity, mask-like facies (see WARNINGS).
Tardive dyskinesia most frequently is characterized by involuntary movements of the tongue, face, mouth or jaw, and sometimes by involuntary movements of the trunk and/or extremities; movements may be choreoathetotic in appearance (see WARNINGS).
Motor restlessness (akathisia) may consist of feelings of anxiety, agitation, jitteriness, and insomnia, as well as inability to sit still, pacing, and foot tapping. These symptoms may disappear spontaneously or respond to a reduction in dosage.
Neuroleptic Malignant Syndrome
Rare occurrences of neuroleptic malignant syndrome (NMS) have been reported. This potentially fatal syndrome is comprised of the symptom complex of hyperthermia, muscular rigidity, altered consciousness, and autonomic instability (see WARNINGS).
Hypotension, hypertension, supraventricular tachycardia, bradycardia, fluid retention, acute congestive heart failure, and possible atrioventricular (AV) block (see CONTRAINDICATIONS and PRECAUTIONS).
Nausea and bowel disturbances, primarily diarrhea.
Rarely, cases of hepatotoxicity, characterized by such findings as jaundice and altered liver function tests, when metoclopramide was administered with other drugs with known hepatotoxic potential.
Urinary frequency and incontinence.
A few cases of neutropenia, leukopenia, or agranulocytosis, generally without a clear-cut relationship to metoclopramide. Methemoglobinemia, in adults and especially with overdosage in neonates (see OVERDOSAGE). Sulfhemoglobinemia in adults.
A few cases of rash, urticaria, or bronchospasm, especially in patients with a history of asthma. Rarely, angioneurotic edema, including glossal or laryngeal edema.
Visual disturbances, Porphyria.
Transient flushing of the face and upper body, without alterations in vital signs, following high doses intravenously.