Ibuprofen

Additional information

Pharmacokinetics and dosing

The effect of patient's sex on the pharmacokinetics after a single dose 600 mg ibuprofen was evaluated in healthy volunteers (18 men, 19 women). Patient's sex did not influence peak plasma concentration or the extent of binding to plasma protein. However, half-life was shorter and oral clearance was higher in young men compared to elderly men and women of all studied ages [6]. No influence of oral contraceptives on ibuprofen pharmacokinetics has been shown [7]. No sex differentiation in dosing has been recommended by the pharmaceutical company [8].

Effects

A meta-analysis evaluated the effect of patient’s sex on ibuprofen 400 mg in men and non-pregnant women with moderate to severe dental pain (119 men, 195 women, 15-35 years of age). No sex differences in analgesic response to ibuprofen were found [9]. A small study investigated the analgesic efficacy of ibuprofen 600 mg on postoperative endodontic pain (8 men, 7 women). There were no differences in pain reduction between men or women in the ibuprofen and placebo group [10]. However, in a small randomized, double-blind, placebo-controlled trial examining the ability of ibuprofen to reduced experimental (voltage induced C-fiber nociceptive activation) pain in healthy young pain-free subjects (10 men, 10 women, 18-30 years of age), analgesic effect of ibuprofen 800 mg was found only in men [11].

A more recent study (10 men, 10 women) analysed sex differences in ibuprofen and placebo analgesia expectancy. In men, both placebo and ibuprofen analgesia were dependent upon expectancy; when they were told they were receiving ibuprofen, they had an analgesic response, even if receiving placebo. In women, ibuprofen was ineffective in producing analgesia regardless of their expectations [12].

Pain relief in children with migraine was examined in a randomized, double-blind, placebo-controlled study (49 boys, 35 girls, age 6-12 years). They were given ibuprofen 7.5 mg/kg or placebo. Boys taking ibuprofen responded effectively while girls did not. No analysis of pharmacokinetics variables was performed [13].

Adverse effects

The PAIN study (3611 men, 5009 women) was a large randomized double-blind trial of the tolerability of paracetamol, aspirin and ibuprofen. Analysis of potential risk factors for adverse events among patients in the PAIN study shows that female sex is one risk factor [14].A nested control study estimated the risk of upper gastrointestinal complications associated with selective cox 2-inhibitors and non-selective NSAIDs compared with non-use of NSAIDs. In all > 600 000 individuals contributed to >1 million person-years of observation and 726 upper gastrointestinal complications were identified. Male sex and high age carried a higher risk of complication and suggested a synergistic effect between these factors and NSAIDs on the risk of upper gastrointestinal complications. The risk for upper gastrointestinal complications differed between the various NSAIDs. Adjusted for male sex and age, the OR for diclofenac was 2.2 compared to 4.0 for naproxen, and 1.6 for ibuprofen [1].A retrospective cohort study (625 307 patients with 2 130 820 prescriptions, one third of these were to men) found that incidence rates of NSAID-induced acute liver injury were similar for men and women and for the young and the elderly [2]. However, a case-control study (136 men, 130 women) found an association between NSAID exposure and liver injury in women but not in men (OR 6.49 vs. 1.06). This may be due to differences in pharmacokinetics or circulating level hormones and/or greater use of multiple medications in women [3] or to a generally higher risk of drug-induced liver injury in women [4].A meta-analysis evaluated NSAID use and the risk of Parkinson’s disease. Pooled risk ratio of Parkinson’s disease were similar in men and women using NSAID (men 0.79 (95%CI 0.69, 0.92); women 0.72 (95%CI 0.45, 1.15)) [5].A cross-sectional study (19 756 men, 18 640 women) investigated the relationship between use of aspirin or ibuprofen and risk of colorectal polyp prevalence. A trend for dose-dependent risk reductions were seen in men using aspirin or ibuprofen > 2 times/day. A trend for protective effects in women were only found among those with BMI <25 and a regular use of aspirin or ibuprofen [15].

Reproductive health issues

Regarding teratogenic aspects, please consult Janusmed Drugs and Birth Defects (in Swedish, Janusmed fosterpåverkan).