Drugs implicated in causing ILD are recorded in the Pneumotox webset (www.pneumotox.com).
Common drugs associated with ILD:
(1) chemotherapeutic agents (bleomycin, gemcitabine, MTOR inhibitors, EGFR targeted, immune checkpoint inhibitors)
(2) antibiotics (nitrofurantoin, daptomycin)
(3) amiodarone
(4) rheumatology drugs (methotrexate, anti-TNF agents, leflunomide)
Risk factors for drug-induced ILD:
(1) older age
(2) smoking
(3) pre-existing lung disease
(4) combination of causative drugs
(5) variable dose dependency
(6) cytochrome P450 polymorphisms
(7) impaired renal function
(8) HLA allelic variants
The appearance on imaging studies and histopathology is similar to other causes of ILD.
Factors associated with a poor prognosis:
(1) presence of diffuse alveolar pattern
(2) acute onset
(3) severity of disease at presentation, especially need for mechanical ventilation
(4) continuing to administer the drug after symptom onset
In many cases discontinuing the causative drug can result in clinical improvement, but some patients have progressive disease despite drug discontinuation.
Differential diagnosis:
(1) radiation pneumonitis
(2) rheumatologic disease associated ILD
(3) infection
(4) other causes of ILD
