Clonidine is used for hypertension and narcotic withdrawal prophylaxis in adults and children. This study described plasma absorption of clonidine from whole and cut transdermal clonidine patches. This was a retrospective descriptive study in an 18 bed multidisciplinary pediatric intensive care unit, evaluating 15 critically ill children with a median age of 1.1 years (range 0.3-11 years) treated with transdermal clonidine for narcotic withdrawal prophylaxis, and who had plasma clonidine concentrations measured. An assessment of the relationship between clonidine dose and patch integrity (whole vs. cut) with plasma concentrations was performed, with further analysis by Spearman Correlation Coefficient. Clonidine doses averaged 7.5±4.2 μg/kg/day (range 2.3-20 μg/kg/day) for 9.8±4.3 days (range 4-20 days). There were 9 cut patches and 6 whole patches. The average prescribed dose delivered by cut patches was 6.4±3 μg/kg/day, resulting in a mean plasma concentration of 1±1.1 ng/ mL (range <0.05-3.3 ng/mL). The average prescribed dose delivered by whole patches was 7±1.7 μg/kg/day, resulting in a mean plasma concentration of 0.55±0.3 ng/mL (range 0.13-1.5 ng/mL). The Spearman Correlation Coefficient was calculated to evaluate the correlation between dose and concentration. For whole and cut patches the correlation coefficient was 0.94 (P=0.005) and 0.72 (P=0.002), respectively. Doses ranging from 1.7 to 20 μg/kg/day using whole patches resulted in no plasma concentrations >2 ng/mL. However, a plasma concentration >2 ng/mL was achieved with a dose of 8.8 μg/kg/day delivered by a cut patch. In addition, the 2 samples that resulted in undetectable concentrations were taken from patients who were treated with cut patches. The results from this pilot study suggest that critically ill children absorb clonidine from transdermal patches, but the rate and extent of absorption appears to be more predictable with the use of whole patches compared to patches that have been cut.
Keywords: clonidine; patch; transdermal.