instruction: how many patients whose drug code is paro10 and lab test category is chemistry?
response: SELECT COUNT(DISTINCT demographic.subject_id) FROM demographic INNER JOIN prescriptions ON demographic.hadm_id = prescriptions.hadm_id INNER JOIN lab ON demographic.hadm_id = lab.hadm_id WHERE prescriptions.formulary_drug_cd = "PARO10" AND lab."CATEGORY" = "Chemistry"