Comprehensive Nursing Pharmacology Q 188
The half-life of morphine is:
A. 4 to 6 hours
B. 2 to 4 hours
C. 6 to 8 hours
D. 30 minutes to 1 hour
Correct Answer: B. 2 to 4 hours
The half-life of morphine is 2 to 4 hours. Other choices are incorrect because they are either longer or shorter than the true half-life of morphine. Oral formulations are available in both immediate and extended-release for the treatment of acute and chronic pain. Pain that is more severe and not well controlled may be manageable with single or continuous doses of IV, epidural, and intrathecal formulations.
Option A: Infusion dosing can vary significantly between patients and largely depends on how naive or tolerant they are to opiates. It is interesting to point out that IV morphine formulation is also commonly given intramuscularly (IM). Morphine is also available as a suppository.
Option C: Morphine is considered the classic opioid analgesic with which other painkillers are compared. Like other medications in this class, morphine has an affinity for delta, kappa, and mu-opioid receptors. This drug produces the majority of its analgesic effects by binding to the mu-opioid receptor within the central nervous system (CNS) and the peripheral nervous system.
Option D: The net effect of morphine is the activation of descending inhibitory pathways of the CNS as well as inhibition of the nociceptive afferent neurons of the PNS, which leads to an overall reduction of the nociceptive transmission.