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Acetaminophen (paracetamol) levels in human tears.
M Lifshitz1, O Weinstein, V Gavrilov
1Toxicology Unit, Soroka University Medical Center, Beer-Sheva, Israel.
Therapeutic Drug Monitoring
|October 16, 1999
Summary
This study found that measuring acetaminophen (paracetamol) in tears is a reliable, noninvasive method. Tear paracetamol levels strongly correlate with serum levels, suggesting tears can be used to monitor drug concentrations.
Area of Science:
- Pharmacokinetics
- Ophthalmology
- Analytical Chemistry
Background:
- Limited information exists regarding drug concentrations in tears.
- Acetaminophen (paracetamol) is a widely used analgesic and antipyretic.
- Noninvasive methods for monitoring drug levels are highly desirable.
Purpose of the Study:
- To measure acetaminophen (paracetamol) levels in human tears.
- To compare tear paracetamol levels with simultaneous serum levels.
- To evaluate the feasibility of using tears for noninvasive drug monitoring.
Main Methods:
- Collected paired tear and serum samples from 10 healthy volunteers at 1 and 2 hours post-ingestion of 1.5g acetaminophen.
- Utilized glass microcapillary tubes for tear collection via conjunctival stimulation.
- Analyzed samples using homogeneous enzyme immunoassay for paracetamol quantification.
Main Results:
- Strong and significant correlations were observed between tear and serum paracetamol levels at both 1 hour (r=0.8, p=0.005) and 2 hours (r=0.85, p=0.002) post-ingestion.
- The mean ratio of tear to serum paracetamol levels was approximately 0.77 at 1 hour and 0.81 at 2 hours.
- Changes in tear paracetamol levels significantly correlated with changes in serum levels (r=0.7, p=0.025).
Conclusions:
- Tear acetaminophen (paracetamol) levels closely mirror serum levels.
- Conjunctival fluid analysis offers a reliable, noninvasive method for monitoring acetaminophen pharmacokinetics.
- This study establishes a foundation for future research into tear drug level monitoring.