A patient has a history of anaphylaxis to morphine, almost died from it. Are there some opioids you can give to them?
Yes. You simply need to choose one that is structurally different.
Opioids are classified into three groups:
- Group 1 – The Natural occurring agents derived from the opium plant. These are the opiates.
- Morphine, codeine, thebaine
- Group 2 – The Semi-synthetics
- Hydrocodone, oxycodone, hydromorphone, oxymorphone, buprenorphine (heroin is also in this group)
- Group 3 – The Synthetics
- Fentanyl (alfentanil, sufentanil, etc.), methadone, tramadol, propoxyphene, meperidine
Group 1 (the naturally occurring agents –opiates) and group 2 (the semi-synthetic) are structurally very similar to each other and should be avoided if there is a true allergy to any of the group 1 and 2 members. The natural and semi-synthetics have cross-reactivity. The structures of the group 3 compounds are sufficiently different that when given to a patient with a true allergy to group 1 or 2 compounds, cross-reactivity doesn’t happen. So you can give it without fear.
In the patient above, any of the synthetic opioids(group 3) above would work.