Pharmacodynamic interaction of naproxen with low-dose aspirin in healthy subjects
Marta L. Capone, PhD*, ,
Maria G. Sciulli, PhD*,,
Stefania Tacconelli, PhD*,,
Marilena Grana, MD*,,
Emanuela Ricciotti, PharmD*,,
Giulia Renda, MD*,,
Patrizia Di Gregorio, MD ,
Gabriele Merciaro and
Paola Patrignani, PhD*,,*
* Department of Medicine and Center of Excellence on Aging, School of Medicine, "G. d’Annunzio" University, Chieti, Italy
"G. d’Annunzio" University Foundation, Ce.S.I., Chieti, Italy
SS Annunziata Hospital, Chieti, Italy.
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Figure 1 Flow chart of study protocols. In the study with multiple daily doses, aspirin (100 mg daily and once at 8 AM) was administered for 6 consecutive days and then naproxen (500 mg twice daily, once at 10 AM and 10 PM) was co-administered 2 h after aspirin for further 6 days to 4 healthy subjects. After a washout period of at least 14 days, the volunteers reversed the treatment, i.e., low-dose aspirin (100 mg daily at 10 AM) was administered 2 h after naproxen (500 mg twice daily, once at 8 AM and once at 8 PM) for further 6 days. Blood samples were collected before and up to 26 h after dosing with the first study drug on the 6th, 12th, 27th, and 32nd study day to assess the inhibition of serum thromboxane (TX)B2 (a capacity index of platelet cyclooxygenase [COX]-1 activity) and lipopolysaccharide-induced prostaglandin E2 production (a capacity index of monocyte COX-2 activity). Three consecutive urinary samples (time of collection: 0 to 6 h, 6 to 12 h, and 12 to 24 h) were collected before treatment and on days 6, 12, 27, and 32 to evaluate the urinary excretion of 11-dehydro-TXB2 (a major enzymatic metabolite of TXB2 that is an index of TXA2 biosynthesis in vivo). In the study with single dose, aspirin (100 mg) and naproxen (500 mg) were co-administered to 5 healthy subjects, and peripheral blood samples were collected before and up to 14 days after dosing to assess the time-dependent inhibition and recovery of serum TXB2 production and platelet aggregation ex vivo.
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Figure 2 Concentration-response curves for the inhibition of plate let cyclooxygenase (COX)-1 activity by aspirin (A) and naproxen (B). One-milliliter aliquots of washed platelets (1.5 x 108 cells) were preincubated with increasing concentrations of aspirin (0.01 to 100 µmol/l) or naproxen (0.01 to 100 µmol/l) for 25 min, and then 0.5 or 10 µmol/l of arachidonic acid (AA) was added for an additional 30 min at 37°C. In panel C, the antagonism of aspirin inhibition of platelet COX-1 by naproxen is shown. Increasing concentrations of naproxen (0.01 to 10 µmol/l) were incubated with washed platelets (1.5 x 108 cells/ml) for 5 min before the addition of aspirin (10 or 100 µmol/l) and the incubation continued for additional 20 min at 37°C. After washing twice, platelets were resuspended in 500 µl of Hanks’ balanced salt solution supplemented with 25 mmol/l HEPES, challenged with 10 µmol/l of AA for 30 min at 37°C, and thromboxane (TX)B2 levels were determined by radioimmunoassay. The data represent the average of inhibition of platelet TXB2 production from five different donors. IC50 = concentrations required to inhibit 50% of enzyme activity.
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Figure 3 Mean inhibition of platelet cyclooxygenase-1 activity ex vivo, as assessed by the measurement of serum thromboxane (TX)B2 levels (A), arachidonic acid-induced platelet aggregation ex vivo (B), and TX biosynthesis in vivo, as assessed by the measurement of urinary 11-dehydro-TXB2 levels (C), in subjects taking low-dose aspirin alone (100 mg daily) for six days (hatched bars) and then readministered with naproxen (500 mg twice daily, with the first dose administered 2 h after aspirin) for further six days (open bars). The solid bars show the effects of the same medications administered in reversed order for further six days after a washout period of 14 days. Values are reported as mean ± SEM, n = 4. All times are hours after the administration of the first study drug. Open bars = aspirin before naproxen (twice daily); solid bars = naproxen (twice daily) before aspirin; hatched bars = aspirin.
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Figure 4 Mean inhibition of monocyte cyclooxygenase-2 activity ex vivo, as assessed by measurement of whole-blood lipopolysaccharide (LPS)-induced prostaglandin (PG)E2 levels in subjects taking low-dose aspirin alone (100 mg daily) for 6 days (hatched bars) and then readministered with naproxen (500 mg twice daily, with the first dose administered 2 h after aspirin) for a further 6 days (open bars). The solid bars show the effect of the same medications, administered in reversed order for further six days after a washout period of 14 days, on monocyte cyclooxygenase-2 activity. The values are reported as mean ± SEM of inhibition (%) of LPS-induced PGE2 levels caused by the different treatments, n = 4. *p < 0.05, **p < 0.01 versus pre-drug values. All times are hours after the administration of the first study drug. Open bars = aspirin before naproxen (twice daily); solid bars = naproxen (twice daily) before aspirin; hatched bars = aspirin.
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Figure 5 Mean inhibition of platelet cyclooxygenase-1 activity ex vivo (solid circles) (as assessed by measurement of serum TXB2) and arachidonic acid-induced platelet aggregation ex vivo (open circles) in subjects taking a single dose of aspirin (100 mg) and naproxen (500 mg). Values are reported as mean ± SEM, n = 5. Serum TXB2 and platelet aggregation were significantly inhibited versus pre-drug values at 3 h (p < 0.01 and 0.05, respectively), 12 h (p < 0.01), 24 h (p < 0.01), and 48 h (p < 0.01 and 0.05, respectively) after dosing. No significant differences were found at 1, 72, 144, 192, and 336 h after dosing versus pre-drug values. Open circles = platelet aggregation; solid circles = serum TXB2.
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