Effect of effervescent paracetamol on blood pressure: a crossover randomized clinical trial

To evaluate the effect of effervescent paracetamol on office and ambulatory blood pressure (BP) compared with noneffervescent paracetamol in hypertensive patients.

This was a multicenter open crossover randomized clinical trial.

Primary care centers in Catalonia and the Basque Country.

Inclusion criteria were office BP 150/95 mmHg or less and daytime ambulatory BP 140/90 mmHg or less, stable pharmacologic or nonpharmacologic antihypertensive treatment, and concomitant chronic osteoarticular pain.

Baseline randomized assignment to 3-week periods of effervescent paracetamol (1 g three times a day) first and noneffervescent paracetamol later, or inversely, during a 7-week study period. At the start and end of each treatment period, 24-h ambulatory BP monitoring was performed.

Differences in 24-h SBP between baseline and end of both treatment periods. The main analyses were performed according to the intention-to-treat principle.

In intention-to-treat analysis, 46 patients were analyzed, 21 were treated with paracetamol effervescent and noneffervescent later, and 25 followed the opposite sequence. The difference in 24-h SBP between the two treatments was 3.99 mmHg (95% confidence interval 1.35-6.63; P = 0.004), higher in the effervescent paracetamol treatment period. Similarly, the per-protocol analysis showed a difference in 24-h SBP between the two groups of 5.04 mmHg (95% confidence interval 1.80-8.28; P = 0.004), higher in the effervescent paracetamol treatment period. Self-reported pain levels did not differ between groups and did not vary by treatment period. No serious adverse events were reported in either study arm.

Effervescent paracetamol tablets are responsible for a significant daytime and overall increase in ambulatory 24-h SBP.

NCT: 02514538 EudraCT: 2010-023485-53.