Warfarin, phenytoin, sulphonylureas and tolbutamide
Chloramphenicol prolongs the elimination, increasing the blood levels, of drugs including warfarin, phenytoin, sulphonylureas, tolbutamide.
Anticonvulsants and anticoagulants
Doses of anticonvulsants and anticoagulants may need to be adjusted if given concurrently.
Penicillins and rifampicin
Complex effects (including reduced / increased plasma levels) requiring monitoring of chloramphenicol plasma levels have been reported with co-administration of penicillins and rifampicin.
Paracetamol
Concurrent administration of paracetamol should be avoided as this prolongs chloramphenicol half-life.
Calcineurin Inhibitors (CNIs) Ciclosporin and Tacrolimus
Treatment with chloramphenicol possibly increases the plasma levels of the CNIs ciclosporin and tacrolimus.
Barbiturates
The metabolism of chloramphenicol is accelerated by barbiturates, such as phenobarbitone, leading to reduced plasma concentrations. There is a possible decrease in the metabolism of phenobarbitone with concomitant chloramphenicol administration.
Oestrogens
There is a small risk that chloramphenicol may reduce the contraceptive effect of oestrogens.
Hydroxocobalamin
Chloramphenicol reduces the response to hydroxocobalamin.
Drugs causing agranulocytosis
Chloramphenicol is contra-indicated in patients taking drugs liable to suppress bone marrow function (see section 4.3). These include:
- Carbamazapine
- Sulphonamides
- Phenylbutazone
- Penicillamine
- Cytotoxic agents
- Some antipsychotics, including clozapine and particularly depot antipsychotics
- Procainamide
- Nucleoside reverse transcriptase inhibitors
- Propylthiouracil