What severe side effect is associated with the use of Busulfex (busulfan)?

Busulfan, marketed as Busulfex, is known to have several potential side effects, and one of the most concerning among them is pulmonary fibrosis. This condition involves the scarring and inflammation of lung tissue, which can lead to significant respiratory problems. The pathophysiology of pulmonary fibrosis related to busulfan is thought to involve direct toxicity to the lung parenchyma, compounded by its alkylating properties that can disrupt cellular function and promote fibrotic changes in the lung.

Patients receiving busulfan, especially as part of conditioning regimens prior to hematopoietic stem cell transplantation, should be monitored for respiratory symptoms and lung function. Recognizing the risk of developing pulmonary fibrosis is crucial, as it can significantly impact the patient's quality of life and overall treatment outcomes.

The other options presented do not typically indicate a severe side effect associated specifically with the use of Busulfex. Although hypotension, peripheral neuropathy, and hemorrhagic cystitis might occur in other contexts or with different chemotherapeutic agents, they are not commonly recognized as risks specifically linked to busulfan treatment.