Differential effects of dopamine on pain-related electric activities in normal rats and morphinistic rats

Droperidol analgesia for opioid-tolerant patients

BACKGROUND

Patients with acute and chronic pain syndromes such as migraine headache, fibromyalgia, and sickle cell disease represent a significant portion of emergency department (ED) visits. Certain patients may have tolerance to opioid analgesics and often require large doses and prolonged time in the ED to achieve satisfactory pain mitigation. Droperidol is a unique drug that has been successfully used not only as an analgesic adjuvant for the past 30 years, but also for treatment of nausea/vomiting, psychosis, agitation, sedation, and vertigo.

OBJECTIVES

In this review, we examine the evidence supporting the use of droperidol for analgesia, adverse side effects, and controversial United States (US) Food and Drug Administration (FDA) black box warning.

DISCUSSION

Droperidol has myriad pharmacologic properties that may explain its efficacy as an analgesic, including: dopamine D2 antagonist, dose-dependent GABA agonist/antagonist, α2 adrenoreceptor agonist, serotonin antagonist, histamine antagonist, muscarinic and nicotinic cholinergic antagonist, anticholinesterase activity, sodium channel blockade similar to lidocaine, and μ opiate receptor potentiation.

CONCLUSION

Droperidol is an important adjuvant for patients who are tolerant to opioid analgesics. The FDA black box warning does not apply to doses below 2.5 mg.

Effect of morphine on brain uracil release in mouse striatum detected by microdialysis

Effect of acute treatment of morphine is associated with neurotransmitter and neuromodulator changes in the brain. A possible relationship between pyrimidines and morphine has also been discussed. Uracil, a common and naturally occurring pyrimidine derivative which found in RNA, has been suggested to modulate many neurotransmitters or neuromodulators, especially in the mature central nervous system. The present study was performed to determine the effect of acutely intraperitoneal morphine treatment on the release of uracil in mouse striatum. The results showed that morphine significantly decreased the release of uracil at the dose of 10 and 20mg/kg in a dose dependent manner. Naloxone could reverse the morphine-induced reduction of uracil levels in mouse striatum, at the dose of 4 mg/kg, without affecting basal uracil release. The results suggest that the extracellular level of uracil in mouse striatum could be specifically regulated by the centrally acting drugs, such as morphine. However, the pharmacological implications of such regulation should be further evaluated.

Endogenous opiates and behavior: 2007

This paper is the thirtieth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2007 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia; stress and social status; tolerance and dependence; learning and memory; eating and drinking; alcohol and drugs of abuse; sexual activity and hormones, pregnancy, development and endocrinology; mental illness and mood; seizures and neurologic disorders; electrical-related activity and neurophysiology; general activity and locomotion; gastrointestinal, renal and hepatic functions; cardiovascular responses; respiration and thermoregulation; and immunological responses.