Can finger‐prick sampling replace venous sampling to determine the pharmacokinetic profile of oral paracetamol?

WHAT IS ALREADY KNOWN ABOUT THE SUBJECT

AIM

The aim of this study was to determine whether paracetamol demonstrates concentration differences between finger‐prick and venous blood samples.

METHODS

Paired finger‐prick and venous blood samples were taken at 0, 15, 30 and 60 min following 1 g oral paracetamol, from 12 male adult subjects. Paracetamol concentration was determined using HPLC and UV detection with a LLOQ of 2200 pg on column. Intra‐assay coefficient of variation for paracetamol at the LLOQ was 3%.

RESULTS

At 15, 30, and 60 min post dose the median finger‐prick paracetamol concentration was 349%, 72%, and 9.3% greater than the equivalent venous concentrations, respectively. Regression analysis confirmed a significant relationship between finger‐prick and venous paracetamol concentrations at 15 min (r² = 0.81, P = 0.006), at 30 min (r² = 0.82, P < 0.0001) and at 60 min (r² = 0.87, P < 0.0001) post dose. The regression equation for venous and finger‐prick blood concentrations at 15, 30 and 60 min post dose were Venous₁₅ = Finger₁₅ − 3.4, Venous₃₀ = Finger₃₀ − 3.4 and Venous₆₀ = 0.68Finger₆₀ + 3.06, respectively.

CONCLUSIONS

Paracetamol demonstrates an arteriovenous difference in concentration, and the use of finger‐prick samples may give rise to results which differ from those obtained with traditional venous sampling especially during the first 1 h following drug ingestion.

DOI: 10.1111/j.1365-2125.2010.03668.x

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