Table 2.

Regimens and drug‐drug interactions of systemic antibiotics

Drug	Dose/Regimen	Drug‐Drug interaction (Gilbert 2018; Micromedex 2018)
Cefadroxil	Adult: 1 g orally daily in a single dose or in divided doses twice a day Pediatric: 30 mg/kg orally once daily or in equally divided doses every 12 hours	Concurrent use of cefadroxil and warfarin may result in increased risk of bleeding Concurrent use of cefadroxil and contraceptives (combination) may result in decreased contraceptive effectiveness
Ciprofloxacin	Adult: 500 mg orally every 12 hours for 7 to 14 days; 400 mg IV every 12 hours for 7 to 14 days	Concurrent use of ciprofloxacin and insulin and oral hypoglycaemics may result in increased or decreased blood sugar Concurrent use of ciprofloxacin and caffeine may result in increased caffeine plasma concentrations Concurrent use of ciprofloxacin and cimetidine may result in increased blood level of ciprofloxacin Concurrent use of ciprofloxacin and cyclosporine may result in an increased cyclosporine plasma concentration Concurrent use of ciprofloxacin and didanosine may result in a decreased ciprofloxacin plasma concentration Concurrent use of ciprofloxacin and cations (e.g. Al3+, Ca2+, Fe2+, Mg2+, Zn2+) (cireate/citric acid) may result in a decreased plasma concentration of ciprofloxacin Concurrent use of ciprofloxacin and methadone may result in an increased plasma concentration of methadone Concurrent use of ciprofloxacin and NSAIDs may result in increased risk CNS stimulation/seizure Concurrent use of ciprofloxacin and phenytoin may result in an increased or decreased plasma concentration of phenytoin Concurrent use of ciprofloxacin and probenecid may result in a decreased plasma concentration of ciprofloxacin Concurrent use of ciprofloxacin and rasagiline may result in an increased plasma concentration of rasagiline Concurrent use of ciprofloxacin and sucralfate may result in decreased absorption of ciprofloxacin Concurrent use of ciprofloxacin and theophylline may result in an increased plasma concentration of theophylline Concurrent use of ciprofloxacin and thyroid hormone may result in a decreased plasma concentration of thyroid hormone Concurrent use of ciprofloxacin and tizanidine may result in an increased plasma concentration of tizanidine Concurrent use of ciprofloxacin and warfarin may result in increased prothrombin time
Clindamycin	Adult: 150 to 300 mg orally every 6 hours, 600 to 1200 mg/d IV or IM divided every 6 to 12 hours Pediatric: 8 to 16 mg/kg/d ORALLY divided every 6 to 8 hours; 15 to 20 mg/kg/d IV or IM divided every 6 to 8 hours	Concurrent use of clindamycin and kaolin may result in decreased absorption of kaolin Concurrent use of clindamycin and muscle relaxants (e.g. atracurium, baclofen, diazepam) may result in increased frequency and duration of respiratory paralysis Concurrent use of clindamycin and St John’s wort may result in a decreased level of clindamycin
Tetracyclines	Adult: 500 mg orally twice daily or 250 mg orally 4 times per day Pediatric: (older than 8 years) 25 to 50 mg/kg orally in 4 equally divided doses	Concurrent use of tetracycline and atovaquone may result in decreased atovaquone levels Concurrent use of tetracycline and digoxin may result in increased toxicity of digoxin Concurrent use of tetracycline and methoxyflurane may result in increased toxicity, polyuria, and renal failure Concurrent use of tetracycline and sucralfate may result in decreased absorption of tetracycline Concurrent use of tetracycline and aluminium, bismuth, iron, or Mg2+ may result in decreased absorption of tetracycline Concurrent use of tetracycline and barbiturates or hydantoins may result in a decreased serum half‐life of tetracycline Concurrent use of tetracycline and carbamazepine may result in a decreased serum half‐life of tetracycline Concurrent use of tetracycline and digoxin may result in an increased serum level of digoxin Concurrent use of tetracycline and warfarin may result in increased activity of warfarin
Trimethoprim‐sulphamethoxazole	Adult: sulfamethoxazole 800 mg/trimethoprim 160 mg to sulfamethoxazole 1600 mg/trimethoprim 320 mg orally twice daily Pediatric: (older than 1 month) based on trimethoprim component: 8 to 12 mg/kg/d orally in 2 divided doses	Concurrent use of trimethoprim‐sulphamethoxazole and angiotensin‐converting enzyme inhibitors may result in an increased serum potassium concentration Concurrent use of trimethoprim‐sulphamethoxazole and amantadine may result in increased serum levels and toxicity of tetracycline Concurrent use of trimethoprim‐sulphamethoxazole and azathioprine may lead to side effects of leukopaenia Concurrent use of trimethoprim‐sulphamethoxazole and barbiturates or hydantoins may result in a decreased serum half‐life of tetracycline Concurrent use of trimethoprim‐sulphamethoxazole and loperamide may result in an increased serum level of loperamide Concurrent use of trimethoprim‐sulphamethoxazole and methotrexate may result in enhanced marrow suppression Concurrent use of trimethoprim‐sulphamethoxazole and oral contraceptives, pimozide, and 6‐mercaptopurine may result in decreased effects of oral contraceptives, pimozide, and 6‐mercaptopurine Concurrent use of trimethoprim‐sulphamethoxazole and phenytoin may result in an increased serum level of phenytoin Concurrent use of trimethoprim‐sulphamethoxazole and rifampin may result in an increased serum level of phenytoin Concurrent use of trimethoprim‐sulphamethoxazole and spironolactone or sulfonylureas may result in an increased serum potassium level Concurrent use of trimethoprim‐sulphamethoxazole and warfarin may result in increased activity of warfarin
Linezolid	Adult: 400 to 600 mg ORALLY every 12 hours for 10 to 14 days Pediatric: (birth through 11 years) 10 mg/kg IV or ORALLY every 12 hours	Concurrent use of linezolid and adrenergic agents may result in increased risk of hypertension Concurrent use of linezolid and clarithromycin may result in an increased blood concentration of linezolid Concurrent use of linezolid and meperidine may result in increased risk of serotonin syndrome Concurrent use of linezolid and rasagiline may result in increased risk of serotonin syndrome Concurrent use of linezolid and rifampin may result in a decreased serum level of linezolid Concurrent use of linezolid and serotonergic drugs may result in increased risk of serotonin syndrome
Glycopeptide (as vancomycin)	Adult: 30 mg/kg/d IV in 2 divided doses or 40 mg/kg/d IV in 4 divided doses	Concurrent use of vancomycin and aminoglycosides may result in increased frequency of nephrotoxicity

Al: aluminium; Ca: calcium; CNS: central nervous system; Fe: iron; Mg: magnesium; NSAIDs: non‐steroidal anti‐inflammatory drugs; Zn: zinc.