What similarity do nicotine, alcohol, cocaine, and barbiturates share that make them pass the blood brain barrier easily?

Nicotine, alcohol, cocaine, and barbiturates make them pass the blood brain barrier easily because it affects the functioning capable of neurotransmitter acetylcholine. This nerve cell is responsible for carrying information from brain to other parts of the body. This information is about movement, memory, respiration and heart beat etc. When a person inhaled these substances, then these substances slow down the function of these nerves cells.