Drug therapy in dental practice: nonopioid and opioid analgesics

Abstract

To prevent patient pain, the clinician may chose from opioid and nonopioid analgesics. It is rational for the practitioner to combine drugs from these classes when managing moderate to severe pain. To select combination regimens wisely, it is necessary to understand the significant pharmacological features of each category alone. Careful selection of an effective analgesic regimen based on the type and amount of pain the patient is expected to have can prevent the stress and anxiety associated with breakthrough pain. The clinician can and should develop a variety of effective, safe analgesic regimens, based on estimates of anticipated pain intensity that use sound pharmacological principles.

Figure 1

Nociceptive pathways. The drawing illustrates [A] incoming nociceptive impulses, [B] ascending nociceptive tracks, and [C] descending inhibitory tracts that act to blunt incoming pain signals. Abbreviations represent the myriad of neurotransmitters that contribute to pain transmission. They reflect potential targets for pharmacologic intervention to control pain.

Figure 2

Synthesis and functions of prostanoids.

Figure 3

Molecular structures of morphine, codeine, and derivatives. Codeine and its derivatives differ from their morphine-derived counterparts only in a methyl substitution (circled). This methyl group prevents adequate binding to the mu opioid receptor that mediates most opioid effects. However, these prodrugs are capable of producing nausea and constipation, which are problematic when high doses are administered to generate enough active metabolite for analgesia. (Asterisks indicate molecular alterations from morphine and codeine.)