Orr 1981.

Study characteristics
Methods	Randomised double‐blind 2‐period cross‐over
Participants	79 people (28 men/51 women) aged 22‐71 years, mean = 46 years Tumour type: variety of neoplasms Chemotherapy regimen: doxorubicin, cyclophosphamide, 5‐fluorouracil (with methotrexate), nitrogen mustard, imidazole carboxamide, nitrosaurea and cytosine arabinoside. No information on doses reported Chemotherapy emetogenicity: high (5‐fluorouracil + methotrexate low risk but only 3/55 people)
Interventions	Dronabinol 7 mg/m2 every 4 hours x 4 doses orally, n = 79 Prochlorperazine 7 mg every 4 hours x 4 doses orally, n = 79
Outcomes	Nausea 24 hours post treatment and adverse events
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not reported
Allocation concealment (selection bias)	Unclear risk	Not reported
Incomplete outcome data (attrition bias) All outcomes	High risk	55/79 (69%) participants in both groups analysed
Selective reporting (reporting bias)	Low risk	Data reported for primary outcome
Other bias	Unclear risk	Assumed washout period sufficient. Unclear if paired analysis was performed. Unclear if groups were balanced at baseline
Blinding of participants and personnel (performance bias) All outcomes	Low risk	"Identical capsule used"
Blinding of outcome assessment (detection bias) All outcomes	Low risk	States "double‐blind"