What major concern is associated with administering anticholinergics to patients with prostate enlargement?

Administering anticholinergics to patients with prostate enlargement is primarily concerning because these medications may worsen urinary obstruction. Anticholinergics work by blocking the action of acetylcholine on muscarinic receptors, which can lead to relaxation of bladder detrusor muscle contractions. In patients with an already compromised urinary flow due to prostate enlargement, this effect can exacerbate urinary retention or obstruction, as the natural pressure necessary to void can be further diminished.

The increased muscle tone in the bladder required to overcome an obstructed outlet is antagonized by anticholinergic drugs, which can hinder the bladder's ability to contract effectively. This can lead to complications such as urinary retention, discomfort, and potential kidney damage from prolonged obstruction. Therefore, careful consideration and alternative therapies should be evaluated when treating patients with both prostate enlargement and conditions that might require anticholinergic medications.