Nitrogen mustard class cytostatic alkylating agent, used as a first line drug in the treatment of multiple myeloma.
2.4% (intravenous route).
Uncommon when administered orally (0.3%).
No deaths reported.
IgA multiple myeloma (55% of cases).
Clinical manifestations (at least 2 prior doses, up to 28 previous doses).
General: anaphylactic shock.
Cutaneous: urticaria, angioedema, rash, pruritus.
Respiratory: interstitial pneumonitis.
Leukocyte migration inhibition test: one positive test in a case of interstitial pneumonitis.
Alkylation reaction may occur in vivo, and altered proteins may serve as new antigens capable of stimulating antibodies to the hapten-protein complex.
Avoidance of the intravenous route. Some reactive patients may be switched to oral melphalan with no further reaction.
Cross reactivity with other alkylating agents is exceptional (cyclophosphamide).