Complex sentence: Phenoxybenzamine (marketed under the trade name Dibenzyline) is a non-specific, irreversible alpha blocker used in the treatment of hypertension, and specifically that caused by pheochromocytoma.
Split into simpler sentences: Phenoxybenzamine (marketed under the trade name Dibenzyline) is a non-specific, irreversible alpha blocker. It has used in the treatment of hypertension, and specifically that caused by pheochromocytoma.