Huang 1983.

Methods	Double‐blind RCT. Parallel design. Duration: 2 weeks. Single centre. Country: USA.
Participants	29 participants with CF experiencing a protocol‐defined exacerbation with sputum bacteria that were sensitive to both azlocillin and carbenicillin. Intervention 1: 12 participants; median (range) age 12.25 (6.5 ‐ 24.5) years; 4 males, 8 females. Intervention 2: 14 participants; median (range) age 12.5 (5.75 ‐ 21) years; 7 males, 7 females.
Interventions	Intervention 1: IV azlocillin 250 mg/kg/day in 5 doses. Intervention 2: IV carbenicillin 500 mg/kg/day in 5 doses.
Outcomes	Lung function (unstated), microbiology, adverse effects and a scoring system.
Notes	3 participants were withdrawn from the study (2 had rashes and 1 developed cholecystitis) and did not contribute data to the analysis. The results are presented in terms of the clinical score and so we shall seek to contact the authors for IPD to contribute to a meta‐analysis.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomisation code developed by statistician and kept in pharmacy.
Allocation concealment (selection bias)	Unclear risk	No detail other than "kept in pharmacy".
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Described as 'double‐blind' but no detail given.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Described as 'double‐blind' but no detail given.
Incomplete outcome data (attrition bias) All outcomes	High risk	Withdrawn participants did not contribute to analysis.
Selective reporting (reporting bias)	Unclear risk	Insufficient information.
Other bias	Low risk	No further biases identified.