Ziprasidone Side Effects
Ziprasidone is generally well-tolerated with notably low risk of weight gain and metabolic disturbances, but requires monitoring for QTc prolongation (5-22 ms increase), somnolence, and extrapyramidal symptoms.
Cardiac Effects
QTc Prolongation is the most clinically significant concern with ziprasidone. The drug causes moderate QTc prolongation of 5-22 milliseconds, which is more than most other atypicals (olanzapine 2 ms, risperidone 0-5 ms, quetiapine 6 ms) but substantially less than thioridazine (25-30 ms) 1. Despite this ECG change, there is no convincing evidence that ziprasidone causes severe cardiac events or torsades de pointes at therapeutic doses 1.
Contraindications and Monitoring:
- Absolute contraindications: Recent MI, severe heart failure, congenital long QT syndrome, concurrent use of other QT-prolonging drugs (dofetilide, sotalol, quinidine, thioridazine, droperidol) 2
- Baseline ECG required before initiation, with repeat ECG after reaching target dose 3
- Check electrolytes (potassium, magnesium) before starting and if patient develops diarrhea/vomiting 2
- Avoid IV administration; use intramuscular route when parenteral dosing needed 1
Neurological Side Effects
Extrapyramidal symptoms (EPS) occur in approximately 13% of patients but ziprasidone has a notably lower incidence of movement disorders compared to haloperidol 4, 5. The absence of dystonia, akathisia, and hypertonia with ziprasidone 20 mg IM is particularly noteworthy 4.
Somnolence is the most common adverse effect (21% vs 7% placebo), with a risk difference of 14% directly attributable to the drug 5. This can be managed by:
- Administering larger portion of daily dose at bedtime
- Temporary dose reduction if excessive
- Reassurance that tolerance often develops over 1-2 weeks
Acute dystonia can occur, particularly after first doses or dose increases. Characterized by involuntary muscle spasms of face, neck, extraocular muscles (oculogyric crisis). Laryngeal dystonia is rare but life-threatening - presents as choking sensation and difficulty breathing 1.
Metabolic Profile (Major Advantage)
Ziprasidone has the most favorable metabolic profile among atypical antipsychotics 6:
- No clinically significant weight gain (comparable to placebo in trials) 6, 5, 7
- Weight gain of only 0-4.4 kg in pediatric studies, compared to 3.8-16.2 kg with olanzapine 6
- No adverse effects on cholesterol, triglycerides, or glucose 7, 8
- May actually improve lipid profile when switching from other antipsychotics 6, 7
- Increases resting energy expenditure, which may explain weight neutrality 9
Common Side Effects (by frequency)
From meta-analysis of 4,132 patients 5:
- Somnolence: 21% (risk difference +14%)
- Extrapyramidal symptoms: 13% (risk difference +6%)
- Headache: 13% (risk difference 0% - not drug-related)
- Insomnia: 11%
- Respiratory disorders: 10%
- Asthenia/fatigue: Risk difference +5%
- Dizziness: Risk difference +4%
- Dyspepsia: Risk difference +4%
Rare but Serious Reactions
Neuroleptic Malignant Syndrome (NMS): Rare but potentially fatal. Signs include very high fever, rigid muscles, confusion, sweating, increased heart rate/blood pressure 2.
Serotonin Syndrome: Can occur when combined with other serotonergic agents. Signs include agitation, hallucinations, racing heartbeat, coordination problems, muscle twitching, nausea, sweating, fever 2.
DRESS (Drug Reaction with Eosinophilia and Systemic Symptoms): Delayed-onset reaction with rash, fever, swollen lymph nodes. Can be fatal 2.
Stevens-Johnson Syndrome: Severe cutaneous reaction with blistering rash, mouth ulcers, skin shedding, fever. Can be fatal 2.
Endocrine Effects
Prolactin elevation is minimal and transient with ziprasidone, unlike risperidone or conventional antipsychotics 3, 8. This reduces risk of:
- Galactorrhea
- Gynecomastia
- Sexual dysfunction
- Menstrual irregularities
- Reduced fertility (though D2 antagonism may still cause reversible fertility reduction) 2
Other Notable Effects
Orthostatic hypotension: Can occur, especially at initiation or dose increases. Advise patients to rise slowly from sitting/lying 2, 8.
Anticholinergic effects: Ziprasidone has no anticholinergic activity, unlike olanzapine, clozapine, or quetiapine 10, 8. This means:
- No constipation
- No urinary retention
- No cognitive impairment from anticholinergic burden
- Safe in anticholinergic toxicity/delirium 4
Critical Prescribing Considerations
Food requirement: Ziprasidone absorption is substantially reduced without food. Must be taken with 500 kcal meal to achieve therapeutic levels 7, 11. Without food, absorption drops by approximately 50%, and this cannot be compensated by increasing dose 7.
Optimal dosing: Target dose of 120-160 mg/day (divided twice daily) is associated with optimal symptom control 7, 11. Doses of 40 mg/day may suffice for maintenance 8. Rapid titration to therapeutic dose is more effective than slow titration 7, 11.
Special Populations
Pregnancy: Limited data; no clear association with major birth defects. Registry available (1-866-961-2388) 2.
Breastfeeding: Present in breast milk; monitor infant for sedation, irritability, poor feeding, extrapyramidal symptoms 2.
Elderly: Consider lower starting dose, slower titration, careful monitoring for orthostasis 2.
Renal impairment: No dose adjustment needed for oral ziprasidone. Use IM formulation with caution due to cyclodextrin excipient 2.
Hepatic impairment: AUC increases 13-34% in cirrhosis; half-life increases to 7.1 hours. Consider dose reduction 2.