A detailed discussion of the absorption, distribution, and elimination of opioids is beyond the scope of this chapter. However, when clinically relevant, details of absorption and elimination of specific opioids are given. Knowledge of duration of action and elimination half-life is useful and is provided in Table.161-1.

Most opioids are more effective when given parenterally than orally, owing to variable but significant first-pass effect. Opioids with good oral potency are codeine, oxycodone, levorphanol, and methadone.

The metabolism of codeine, morphine, propoxyphene, oxycodone, meperidine, and methadone is mostly hepatic. The hepatic metabolites may be pharmacologically active. Concurrent use of benzodiazepines, barbiturates, and alcohol is common in the opioid abuser either because of their additive effect or their capacity to inhibit hepatic metabolism, especially the metabolism of methadone. Cyclic antidepressants and propoxyphene also decrease methadone metabolism.

Was this article helpful?

0 0
Peripheral Neuropathy Natural Treatment Options

Peripheral Neuropathy Natural Treatment Options

This guide will help millions of people understand this condition so that they can take control of their lives and make informed decisions. The ebook covers information on a vast number of different types of neuropathy. In addition, it will be a useful resource for their families, caregivers, and health care providers.

Get My Free Ebook

Post a comment