Which agents are known to cross the blood-brain barrier (BBB)?

Physostigmine and Atropine are known to cross the blood-brain barrier (BBB) effectively due to their chemical properties. Physostigmine, in particular, is a reversible inhibitor of acetylcholinesterase and is lipophilic enough to penetrate the BBB, which makes it useful in treating conditions like anticholinergic toxicity and certain types of glaucoma. It acts on the central nervous system (CNS), enhancing cholinergic transmission.

Atropine, although it is primarily known for its peripheral anticholinergic effects, can also affect the CNS. While its effects are more significant at peripheral sites, it does have central effects and can cross the BBB, which contributes to its use in treating bradycardia and in various other medical scenarios.

The other agents in the remaining choices lack the necessary properties to effectively cross the BBB. Glycopyrrolate, for instance, is less lipophilic and primarily acts peripherally on muscarinic receptors, making it unlikely to penetrate the BBB significantly. Neostigmine and Pyridostigmine, while they are both used for their cholinergic effects, do not readily cross into the CNS due to their quaternary ammonium structure, which limits their