IbuprofenPainAnti-Inflammatory Agents, Non-SteroidalChronic PainPain ManagementPain, PostoperativePain ThresholdPain MeasurementAnalgesics, Non-NarcoticLow Back PainBack PainAbdominal PainNeck PainPain, IntractableAcetaminophenPelvic PainPain PerceptionFacial PainAcute PainPain, ReferredCyclooxygenase InhibitorsNaproxenDiclofenacShoulder PainAntipyreticsMusculoskeletal PainAnalgesicsDuctus Arteriosus, PatentDouble-Blind MethodKetoprofenTherapeutic EquivalencyNociceptive PainNeuralgiaAnalgesics, OpioidCyclooxygenase 2 Inhibitors