The time an absorbed opioid drug takes to enter the brain is affected by:
A) the formulation of the drug used.
B) whether or not the drug is synthetic or semisynthetic.
C) the affinity of the drug for opioid receptors.
D) passage through the blood-brain barrier.

Question

Quizplus · Accepted Answer

passage through the blood-brain barrier is the main factor that determines the time an opioid drug takes to enter the brain. The blood-brain barrier is a selectively permeable membrane that impedes the entry of most substances, including drugs, from the bloodstream into the brain. Opioids that have high lipid solubility, low molecular weight, and are uncharged or weakly charged can more easily cross the blood-brain barrier and reach their target receptors in the brain, resulting in faster onset of action.

The Time an Absorbed Opioid Drug Takes to Enter the Brain