Psoriasis treatment: Unconventional and non-standard modalities in the era of biologics

Table 3 Methotrexate drug interactions of significance

Interacting drug	Mechanism/comments
Drugs that increase methotrexate drug levels and toxicity
Salicylates	Decrease renal excretion, displacement from plasma proteins
NSAIDs	Decrease renal excretion, displacement from plasma proteins
Sulfonamides	Decrease renal excretion, displacement from plasma proteins
Dipyridamole	Increased intracellular accumulation of methotrexate
Probenecid	Increased intracellular accumulation of methotrexate, decreased renal tubular function
Chloramphenicol	Displacement from plasma proteins
Phenothiazines	Displacement from plasma proteins
Phenytoin	Displacement from plasma proteins
Tetracyclines	Displacement from plasma proteins
Drugs that simultaneously inhibit folate metabolic pathway-increase hematologic toxicity
Trimethoprim	Inhibition of dihyrofolate reductase
Sulfonamides	Inhibition of dihydropteroate synthetase
Dapsone	Inhibition of dihydropteroate synthetase
Drugs that may synergistically increase hepatotoxicity-common target organ
Systemic retinoids	Common target organ for toxicity-liver
Alcohol	Common target organ for toxicity-liver

NSAID: Nonsteroidal anti-inflammatory drug.