Question

A 65-year-old woman with breast cancer is receiving hospice care in her home. She is cur- rently receiving a long-acting opioid analgesic supplemented with a short-acting combination opioid and nonnarcotic medication for break- through pain. A. Explain the difference between the mecha- nisms and treatment of acute and chronic pain. B. Describe the action of opioid drugs in the treatment of pain. C. Define the terms tolerance and cross-tolerance as they refer to the use of opioids for treatment of pain.

Answer 1

1-Acute pain derives from combined effects of stimulated nociptors local inflammation ,systemic stress response mediters,and psychological factors.

2- Opioids attach to proteins called opid receptors on nerve cells in the brain,spinal cord,gut and other parts of the body.the opiods blocks pain messages sent from the body through the spinal cord to the brain.Opioids produce their effects by acting on specefic opioid receptors mu,kappa and delta.these receptors are present in the CNS and other tissues.Stimulation of opiod receptor finally results in a decreasse in the intracellular caicium which in turn decrease the release of neurotransmitters.

3-Toleracne is a phrmacological concept describing subjects reduced reaction to a drug following its repeated use.Increassing its dosage may re-amplyfy the effects of drugs.

Cross tolerance is a phenomena that occurs when tolerance to the effects of a certain drug produces tolerance to another drug.It often happens between two drugs with similar functions or effects.

Toleraance is defined as a requirement for increased doses of an opiod to acheive the same analgesic efefct.In clinical practice the development of either of these phenomena will lead to increased pain with the usual consequenss of escalating dose of opiod.Complete cross tolerance can develop as evidanced by the lack of anlgesic effect.