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Enteral absorption and haemodynamic response of clonidine in infants post-cardiac surgery.

British journal of anaesthesia (2014-08-01)
S Arenas-Lopez, H Mulla, S Manna, A Durward, I A Murdoch, S M Tibby
ABSTRACT

Clonidine is a useful analgesic-sedative agent; however, few data exist regarding its use in infants after congenital heart disease surgery. We thus aimed to assess the absorption and safety of enterally administered clonidine in this setting. Sixteen infants (median age 6.7 months) received a single nasogastric dose of 3 μg kg(-1) clonidine 2-6 h after surgery. Blood samples were obtained at seven time intervals (up to 480 min). Plasma concentration profiles were obtained, and then pooled with a previous study (137 samples, 30 infants) for estimation of population pharmacokinetic parameters (NONMEM version 7.2). Enteral absorption showed considerable inter-individual variability, with clonidine Cmax ranging from 0.15 to 1.55 ng ml(-1) (median 0.73), and Tmax from 12 to 478 min (median 190). Although therapeutic sedative plasma concentrations were achieved in 94% of patients, only half had attained this by 70 min post-dose. Patients who did not receive inotropes exhibited a positive association between cumulative morphine dose and Tmax (interaction effect P=0.03); this was not seen among those receiving inotropes. The haemodynamic profile was favourable; few patients required fluid boluses, and this bore no relationship to plasma clonidine concentration. Population pharmacokinetic parameter estimation yielded results similar to previous paediatric studies: clearance 13.7 litre h(-1) 70 kg(-1) and Vd 181 litre 70 kg(-1). Early postoperative enteral clonidine produces favourable haemodynamic profiles and therapeutic plasma concentrations in the majority of cardiac surgical infants; however, the time to achieve this can be erratic. Thus, parenteral administration may be preferable if rapid analgo-sedative effects are needed.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Formic acid, reagent grade, ≥95%
Sigma-Aldrich
Formic acid, puriss. p.a., ACS reagent, reag. Ph. Eur., ≥98%
Sigma-Aldrich
Formic acid, ACS reagent, ≥96%
Sigma-Aldrich
Formic acid, puriss., meets analytical specifications of DAC, FCC, 98.0-100%
Sigma-Aldrich
Formic acid, ACS reagent, ≥88%
Sigma-Aldrich
Formic acid, ≥95%, FCC, FG
Sigma-Aldrich
Formic acid solution, BioUltra, 1.0 M in H2O
Supelco
Morphine solution, 100 μg/mL in methanol, ampule of 1 mL, certified reference material, Cerilliant®
Supelco
Clonidine solution, 1.0 mg/mL in methanol, ampule of 1 mL, certified reference material, Cerilliant®