Objective: To evaluate the effects of propofol and propofol containing diso
dium edetate (ethylenediaminetetraacetic acid [EDTA]) on the parathyroid-ca
lcium axis in normal subjects.
Design: Randomised, double-blind, age-stratified, crossover trial. Setting:
Single centre.
Patients: A total of 50 healthy subjects.
Interventions: Each subject was randomised to receive propofol or propofol
containing EDTA on day 1 and the alternate treatment between days 15 and 29
, with a 2-week washout period in between. On the day of treatment, subject
s received a bolus of trial medication (1 or 2 mg/kg) followed by a 60-minu
te observation period. At the end of 60 minutes, subjects received trial me
dication infused for 60 minutes at 1 of 4 randomised infusion rates (25, 50
, 100, or 200 mug/kg per min). Subjects were monitored for an additional 60
minutes following the infusion.
Measurements and Results: Blood pressure, heart rate, respiratory rate, oxy
gen saturation, blood ionised calcium concentration, serum total magnesium
concentration, serum intact parathyroid hormone (PTH) level, and plasma EDT
A level were assessed at periodic intervals during and following the bolus
and continuous infusion of trial medication. Mean arterial pressure signifi
cantly decreased (p < 0.05) following the bolus injection of both trial med
ications and returned to baseline at 60 minutes; it significantly decreased
again during the continuous infusion and returned to baseline during recov
ery. Heart rate and respiratory rate fluctuated in both groups with signifi
cant increases and decreases throughout the study period following the bolu
s injection; both returned to baseline during the recovery period in each g
roup. Ionised calcium and total magnesium concentrations remained within no
rmal limits and were unchanged in response to both study medications. PTH l
evels significantly increased following the bolus injection of both study d
rugs. The increase in PTH levels was greater with higher doses of study med
ication during the infusion period. There was no difference in the response
of blood pressure, heart rate, respiratory rate, or PTH levels between pro
pofol and propofol with EDTA. EDTA levels increased significantly during th
e infusion of propofol with EDTA, reaching mean levels of 240 ng/mL.
Conclusions: The results of this study indicate that propofol increases PTH
levels in normal subjects; however, propofol with EDTA does not alter ioni
sed calcium or total magnesium concentrations.