- A Cochrane review finds moderate-quality evidence that add-on oral olanzapine (Zyprexa) doubles the prophylactic value of standard antiemetic therapy for chemotherapy-induced nausea and vomiting (CINV).
Why this matters
- Olanzapine is an antipsychotic not currently indicated for CINV prophylaxis.
- Cochrane meta-analysis of 14 randomized controlled trials (n=1917) of oral olanzapine in 24 different cancers; most (12) involved highly or moderately emetogenic chemotherapy (HEC/MEC).
- Funding: National Institute for Health Research.
- 3 studies (n=561) with HEC/MEC in solid tumors, moderate-quality evidence:
- Add-on olanzapine doubles likelihood of CINV absence vs placebo/standard therapy (50% vs 25%; risk ratio [RR]=1.98; 95% CI, 1.59-2.47).
- Number needed to treat: 5 (95% CI, 3.3-6.6).
- 7 studies (n=889; low-quality evidence): uncertain elevated risk for serious adverse events (absolute difference, +0.7% [95% CI, 0.2%-5.2%]; RR=2.46 [95% CI, 0.48-12.55]).
- 5 studies (n=464; moderate-quality evidence): olanzapine likely increases somnolence and fatigue vs no treatment/placebo (anticipated absolute risk, +8.2% [95% CI, 1.9%-18.8%]; RR=2.33 [95% CI, 1.30-4.18]).
- Olanzapine likely reduces delayed nausea (3 studies [n=585]: RR=1.71; 95% CI, 1.40-2.09) and vomiting (5 studies [n=702]: RR=1.28; 95% CI, 1.14-1.42).
- Unclear whether 5-mg is similarly effective to 10-mg dose, but may lower odds of somnolence/fatigue.
- Single studies suggest benefit over metoclopramide, 5-HT3 antagonists, and dexamethasone.
- Oral administration only.
- Some studies await classification.