which substances are not able to cross the blood brain barrier under normal circumstances? ampicillin, insulin, ethanol, botulinum or all of these substances

which substances are not able to cross the blood brain barrier under normal circumstances? ampicillin, insulin, ethanol, botulinum or all of these substances

Answer

• botulinum

Explanation:

There is no barrier for ethanol in the brain, that's why ethanol crosses the blood-brain-barrier very easily because of polariy and lipophilic nature of ethanol mixing easily with fat. Insulin also crosses the blood brain barrier by the use of saturatable transporter. Ampicillin also crosses the BBB. Botulinum is a neurotoxin with a size of 150 kD which makes it hard for this toxin to penetrate the blood brain barrier whose cells are tightly packed