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

The correct choice is based on the unique properties of the drugs selected and their ability to effectively penetrate the blood-brain barrier (BBB). Physostigmine is a reversible inhibitor of acetylcholinesterase, which allows it to cross the BBB due to its lipophilic nature. This characteristic facilitates the drug’s use in treating anticholinergic toxicity, as it can influence central nervous system activity directly.

Atropine, while primarily acting on peripheral muscarinic receptors to block the effects of acetylcholine, can also have central effects when it crosses the BBB. It is commonly used to increase heart rate and reduce salivation during surgeries, but it can also lead to CNS effects such as sedation and hallucinations, reinforcing that it has the capacity to enter the central nervous system.

In contrast, the other combinations do not include agents known for their ability to effectively cross the BBB. Glycopyrrolate and neostigmine, for example, are typically more polar and do not penetrate the barrier well, limiting their effects to the peripheral nervous system. Similarly, pyridostigmine is a quaternary ammonium compound with limited central nervous system activity.

Thus, the presence of both physostigmine and atropine in