Final answer:
A patient with glaucoma should not take oxybutynin because this muscarinic antagonist can cause serious adverse reactions by increasing intraocular pressure, worsening the condition. Oxybutynin opposes the effects needed to manage glaucoma and is thus contraindicated.
Step-by-step explanation:
A patient with glaucoma should not take oxybutynin, a muscarinic antagonist, due to the potential for serious adverse reactions. Oxybutynin can cause an increase in intraocular pressure, worsening glaucoma.
Direct answer in 2 lines:
- Patients should not take a drug that is contraindicated because of its potential for serious adverse reactions.
Step-by-step explanation:
Oxybutynin acts as a muscarinic antagonist, meaning it blocks the action of acetylcholine at muscarinic receptors. These receptors are found throughout the body, including in the eye where they help control the outflow of the aqueous humor, the fluid in the eye that maintains eye pressure. When these receptors are blocked, the outflow can be reduced, leading to an increase in intraocular pressure, which is dangerous for individuals with glaucoma.
In the case of atropine poisoning, the antidote is a muscarinic agonist, such as pilocarpine, not a muscarinic antagonist like oxybutynin. Pilocarpine works by activating the muscarinic receptors, counteracting the effects of atropine.