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Changes in pupil diameter after oral administration of codeine
J E Peacock1, P D Henderson, W S Nimmo
1University Department of Anaesthesia, University of Sheffield Medical School.
British Journal of Anaesthesia
|November 1, 1988
Summary
Opioid medications like codeine cause pupil constriction, which can indicate their effect. This study found that codeine significantly reduced pupil size in healthy volunteers, correlating with drug levels in their blood.
Area of Science:
- Pharmacology
- Ophthalmology
- Clinical Pharmacology
Background:
- Opioids are known to cause pupillary constriction.
- Pupil size changes can serve as a potential biomarker for opioid activity.
Purpose of the Study:
- To investigate the relationship between oral codeine administration, plasma codeine concentrations, and pupillary diameter.
- To assess the utility of pupillary constriction as a marker of opioid effect.
Main Methods:
- A randomized, placebo-controlled study involving 16 healthy volunteers.
- Measurement of plasma codeine concentrations and pupil diameters following oral administration of placebo or codeine.
Main Results:
- Codeine administration resulted in a significant decrease in pupil diameter compared to placebo.
- A statistically significant correlation was observed between plasma codeine concentrations and pupil size reduction (P < 0.05).
Conclusions:
- Pupillary constriction is a measurable and significant effect of oral codeine.
- Pupil size serves as a reliable indicator of opioid activity and plasma concentrations.