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Urinary Concentrations of Topically Administered Pain Medications
Michele A Glinn1, Andrew J Lickteig1, Luke Weber1
1Essential Testing LLC, 1616 Eastport Plaza Dr, Collinsville, IL 62234, USA.
Journal of Analytical Toxicology
|April 5, 2017
Summary
Topical analgesics show varied urine drug levels compared to oral forms. Gabapentin and amitriptyline are less detectable topically, while ketamine and cyclobenzaprine are more detectable, impacting compliance monitoring.
Area of Science:
- Pharmacology
- Toxicology
- Pain Management
Background:
- Long-term oral analgesic use risks morbidity, addiction, and misuse.
- Topical analgesic formulations may reduce abuse potential.
- Limited data exists on transdermal drug delivery efficiency and expected urine drug levels.
Purpose of the Study:
- To compare urine drug levels for orally and topically administered analgesics.
- To assess the detectability of gabapentin, ketamine, cyclobenzaprine, and amitriptyline in urine based on administration route.
- To provide data for urine drug testing compliance monitoring in patients using topical analgesics.
Main Methods:
- Analysis of over 29,000 urine specimens.
- Testing for gabapentin, ketamine, cyclobenzaprine, and amitriptyline.
- Comparison of drug concentrations between oral and topical administration groups.
Main Results:
- Gabapentin and amitriptyline urine concentrations were lower with topical use.
- Ketamine was more detectable in topical users, with levels 68-100% of oral users.
- Cyclobenzaprine detectability was similar for oral and topical routes, but mean levels were lower with topical use.
Conclusions:
- Urine drug testing interpretation requires consideration of the analgesic administration route (oral vs. topical).
- Variations in detectability correlate with known percutaneous absorption efficiencies.
- Findings support the need for route-specific reference ranges in urine drug monitoring.