Ibuprofen is indicated and FDA-approved for use in the treatment of inflammatory diseases and rheumatoid disorders. The discovery of ibuprofen was spurred by finding an alternative non-corticosteroid treatment for rheumatoid arthritis. The disease was the initial impetus for the creation of what would eventually become known as ibuprofen; Dr. Stewart Adams OBE was the researcher whose work would lead to the discovery of the drug. Initially patented as 2-(4-isobutylphenyl) propionic acid in 1961 by Dr. Adams and John Nicholson, ibuprofen became and remains one of the most widely used NSAIDs worldwide.[1] Today, ibuprofen remains a monotherapy for managing of pain in rheumatoid disorders and inflammatory diseases, with a portion of research centered around the creation of novel treatments or drugs. One such study involves the creation of NSAID and carbonic anhydrase inhibitor hybrid drugs for the management of pain in rheumatoid arthritis.[2]

Ibuprofen is also FDA-approved for use in mild to moderate pain. It is also available as an over-the-counter medication for pain, usually mild. Some common over-the-counter uses for ibuprofen are muscle sprains or strains, joint aches, pain from migraine, sore throat, and pain from cold or cases of flu. Some of the current research into the use of ibuprofen as a treatment for various sources of pain typically focuses on comparing treatment efficacy with other NSAIDs, with an emphasis on COX-2 inhibitors, or with novel treatment methods. A study comparing COX-2 inhibitors with ibuprofen after third molar removal showed no statistically significant differences in pain relief after 6, 8, and 12 hours, but a significant increase in rescue analgesia use in the ibuprofen group after 24 hours. Researchers also noted a greater instance of nausea and vomiting in the ibuprofen group.[3] Postoperative pain is an area where ibuprofen has had demonstrated efficacy: In a randomized, double-blind study comparing IV ibuprofen and IV acetaminophen use for postoperative pain treatment in patients who underwent laparoscopic cholecystectomies, IV ibuprofen was shown to have lower pain scores and reduced opioid use in the first 24 hours following procedure compared to acetaminophen.[4] Lastly, a trial focusing on ibuprofen administration along with adjunct medication (baclofen, tizanidine, or metaxalone) or placebo for acute low back pain in an emergency department setting showed no improvement of functioning or pain by one week for any of the adjunct medication groups as compared to placebo.[2] Though ibuprofen is already widely accepted as an effective treatment for pain, research is continually seeking to add more effectiveness to the clinical use of ibuprofen in pain treatment.

Ibuprofen is also an FDA-approved antipyretic, used for fever reduction in both adults and children. The use of NSAIDs in treating fever is much more commonplace in pediatric patients, and much contemporary research centers around creating more efficacy in the usage of ibuprofen in treating pediatric fever. A literature review in 2017 showed little evidence to suggest superior efficacy between either ibuprofen or paracetamol in the treatment of fever. Six studies evaluated in the review showed a marginal difference with ibuprofen, but data remained insufficient to state ibuprofen as producing better outcomes.[5] In a related study, refractory fevers responded more favorably to alternating acetaminophen and ibuprofen dosing compared with monotherapy of either, but only in those patients who respond positively after the first cycle.[6]

Dysmenorrhea is a medical condition involving pain during menstruation, which may vary in quality and timing. Dysmenorrhea may be either primary, which is usually mediated by prostaglandin production during ovulation, or secondary from another disease such as endometriosis or pelvic inflammatory disease.[7] NSAIDs are often a therapeutic choice, and FDA-approved to treat primary dysmenorrhea. A study exploring the use of cinnamon as an alternative treatment for primary dysmenorrhea study showed beneficial effects for pain reduction when compared with placebo, but a weaker effect than ibuprofen.[8] Transdermal drug delivery has been a topic of research in the context of ibuprofen and primary dysmenorrhea; a study investigated the use of essential oils as penetration enhancers for transdermal delivery of ibuprofen in patients with dysmenorrhea. This study was motivated by the known risk of GI bleeding and ulceration after oral NSAID usage and sought to investigate a potentially efficacious method of delivery that would decrease these risks. The study found that one of the essential oils, chuanxiong oil, did have positive effects on permeation and pain alleviation when administered with ibuprofen hydrogel.[9]

Ibuprofen and other NSAIDs are also FDA-approved to treat osteoarthritis, often after non-pharmacological measures such as weight loss and strengthening exercises are used. Adjunct medication usage has been explored, with a study showing promise with enhanced outcomes using acupuncture alongside topical ibuprofen compared with topical ibuprofen alone in patients with chronic knee pain due to osteoarthritis.[10] A comparative study between celecoxib and ibuprofen showed equal tolerance and efficacy between the two in the treatment of patients with knee osteoarthritis.[11]

The use of ibuprofen for treatment of gout attacks or flares has been long-researched, with Schweitz et al. in 1978 demonstrating the rapid improvement and symptom resolution in 10 patients with acute gouty arthritis after being treated with 2400 mg of ibuprofen.[12] NSAIDs are commonly used as monotherapy for mild flares, and with colchicine as dual therapy for moderate or severe flares. Treatment of acute gout flares is an off-label use for ibuprofen.

NSAIDs and colchicine are also often used in the treatment of pericarditis, owing to NSAID’s anti-inflammatory and analgesic properties. Ibuprofen is one of the more well-documented NSAIDs in the treatment of pericarditis, with research into its effectiveness in treating and preventing multiple recurrences of idiopathic pericarditis compared with aspirin done in the CORP and CORP-2 trials starting in 2011. Findings showed no significant difference between treatment or prevention of idiopathic pericarditis between the two drugs.[13] Colchicine was shown in a 2014 review to be effective in reducing instances of recurrent pericarditis when used as adjunctive therapy to NSAIDs such as ibuprofen, aspirin, or indomethacin, but with limitations in the number of trials and the statistical power of said trials.[14] Treatment of pericarditis with ibuprofen is an off-label use.

Intravenous ibuprofen has been FDA-approved for the closure of patent ductus arteriosus (PDA) in premature infants and has demonstrated to be as effective as indomethacin in treating PDA. Differences exist in the amount of systemic vasoconstriction and renal toxicity; likely due to less COX-1 selectivity, ibuprofen has been shown to have decreased rates of both outcomes.[15]

Since 2007, the USPSTF has recommended the use of aspirin and NSAIDs in preventing colorectal cancer in specific populations. In 2016, they updated this statement along with their 2009 statement for aspirin and NSAID use in preventing cardiovascular disease.[16] Although the recommendations are not for ibuprofen specifically, they still suggest a strong foundation of research that supports a potentially greater role of NSAIDs in the treatment and prevention of cancer. Burgeoning research on the efficacy of NSAIDs in the realm of cancer treatment, with some research specifically on the efficacy of ibuprofen, has shown promise. A review by Hil’ovska et al. showed potential uses for NSAIDs in reducing cancer cell growth, movement, and invasion; in the induction of cancer cell-death; and in facilitating a lower dose of cytotoxic drug usage.[17] The studies reviewed primarily focused on COX-2 inhibitors. For ibuprofen specifically, some studies have suggested a stronger anticancer effect than aspirin against breast and lung cancer,[18] as well as a reduction in the risk of breast cancer with ibuprofen or aspirin use.[19]

Similarly, Wawro et al. have shown a potential indication for NSAID use, particularly aspirin and ibuprofen, during cancer treatment in patients with colorectal cancer who are undergoing vincristine monotherapy. The purported role of NSAIDs is primarily in preventing chemoresistance by inhibiting the proliferation of cancer-associated fibroblast formation. Vincristine stimulates the growth of cancer-associated fibroblasts via the secretion of tumor growth factors beta and interleukin-6; the researchers saw an inhibitive effect on this process with aspirin and ibuprofen usage. Their research purports that the likely mechanism behind this involves NSAIDs affecting the rate of regulation of microtubule polymerization.[20]

The primary mechanism of Ibuprofen, an NSAID, is through the inhibition of prostaglandin precursors. After a physiological or pathological stimulus, membrane phospholipids release arachidonic acid due to the enzyme phospholipase A2. Arachidonic acid then undergoes passage into one of three different enzymatic pathways: cyclooxygenase (COX), lipoxygenase (LOX), and cytochrome P450 (CYP450). The cyclooxygenase pathway converts arachidonic acid to prostaglandins, prostacyclins, and thromboxanes. The lipoxygenase pathway yields hydroxyeicosatetranoic acids (HETEs), leukotrienes, and lipoxins from arachidonic acid metabolism. Lastly, arachidonic acid converts to HETEs and epoxyeicosatrienoic acids (EET) via the cytochrome P450 pathway.[17]

These metabolic pathways all create products referred to as eicosanoids, which are molecules that are involved in the intercellular and intracellular signaling processes of a variety of physiological processes: smooth muscle tone regulation, vascular permeability, transporter proteins, platelet aggregation, and cell proliferation. As in the case of cyclooxygenase pathway products, eicosanoids also have involvement in autoimmunity, angiogenesis, atopy, inflammation, and cancer.[21]

In terms of the current indicated uses of ibuprofen, the cyclooxygenase pathway plays a prominent role. There are three distinct isoforms in the COX pathway: COX-1 (PGH synthase), COX-2, and COX-3. COX-1 is a constitutionally expressed isoform, with levels relatively stable in reaction to most physiologic or pathologic stimuli. In contrast, COX-2 expression is highly inducible by mitogenic and inflammatory stimuli. Among these, the more well-known are transforming growth factor, fibroblast growth factor, vascular endothelial growth factor, and tumor necrosis factors. The function of COX-3 isoform is still largely unknown and remains a topic of contemporary research.[22][17] Inhibition of COX-1 and COX-2 pathways decreases the expression of prostaglandin precursors; this, in turn, lessens the degree of cellular response to pathologic or physiologic stimuli. It is by this mechanism that non-selective NSAIDs such as Ibuprofen derive their analgesic, antipyretic, and anti-inflammatory properties.[17] For ibuprofen specifically, COX-1 is inhibited approximately 2.5 times more potently than COX-2, which suggests implications into much research of the comparative efficacy of COX-2 selective inhibitors in treating diseases normally treated with ibuprofen.[13]

COX-2 aside from its well-known roles in inflammation has also been found to get constitutively expressed during early carcinogenesis.[8] Research has noted higher levels of COX-2 have demonstrated in several human tumors, including breast, colorectal, esophageal, lung, and pancreatic.[17] The current findings on COX-2 and its various effects on cells suggest that the anticancer effects of NSAIDs, such as Ibuprofen are due to COX-2 inhibition. Though the anticancer effects of COX-2 inhibition are well-documented, there is still some question as to the exact mechanism by which this occurs. Moreover, there is also evidence that other pathways may be involved in the anticancer and antitumor effects of NSAIDs, due to NSAID reducing cell survival in both COX-2 overexpressed as well as COX-2 deficient malignant cells.[23]

For the other two enzymatic pathways, a sizeable amount of research on their potential involvement in carcinogenesis has been conducted, but the information is still limited. LOX isoforms, particularly 5-LOX, 12-LOX, and 15-LOX, have been discussed as potential contributors to tumor development and growth. 5-LOX is normally expressed only in immune cells and has been implicated in the early stages of colon cancer, carcinogenesis in oral cavity tissue, and the expression of chronic myeloid leukemia.[24][25][26] 12-LOX has proangiogenic functions, as it controls G1/S-phase arrest via a dual process: regulation of Nf-kB, and inhibition of Akt and mitogen-activated protein kinases.[10] 15-LOX isoforms promote cell senescence and suppress cell cycle progression.[27]

Ibuprofen, an over-the-counter drug in most countries, is available in forms convenient for consumer consumption. Typical dosage formulations include oral capsule, oral suspension, oral tablet, chewable tablet, intravenous solution, topical gel, and combination kit. The recommendation with oral administration is usually to consume the drug with food or milk in both adults and children. IV administration is often an option in inpatient settings for convenience of delivery or when oral delivery is unavailable,[15][4] and infusion should be over at least 30 minutes for adults, and 10 minutes in pediatric patients. Ibuprofen with lysine is a commonly used IV formulation. Ibuprofen should not be administered simultaneously with total parenteral nutrition but may still use the same line, pausing total parenteral nutrition for 15 minutes before and after ibuprofen dosing. Burgeoning research is hoping to further explore the possibility of simultaneous delivery of ibuprofen with other IV medications or nutrition. A recent study exploring the chemical compatibility of continuous ibuprofen lysine infusion with total parenteral nutrition was conducted recently in 2018, which showed both physical and chemical compatibility of IV ibuprofen infusion with two different total parenteral nutrition formulations in neonates with PDA.[28] Topical application of ibuprofen is also currently under research as a more efficient means of treating diseases known to be susceptible to ibuprofen, such as osteoarthritis and dysmenorrhea.[9][29]

Gastrointestinal bleeding is a well-known adverse effect of ibuprofen usage and can lead to gastritis, ulceration, hemorrhage, or perforation. Inhibition of COX isoforms in ibuprofen usage leads to the reduction of prostaglandins, which play a role in the secretion of gastroprotective mucus.[30] This effect is more pronounced in non-selective NSAIDs, with COX-2 selective NSAIDs having a lower incidence of gastrointestinal complications, which is of particular concern in children, for which the use of ibuprofen is higher than other NSAIDs due to its comparative safety compared to other drugs in its class. Usage of ibuprofen over-the-counter without medical consultation also increases the risk of high dosage levels and short-term interval dosing that may precipitate gastrointestinal complications.[31]

Diminished renal function is also a concern with ibuprofen usage, with a recent surveillance study showing NSAIDs having nephrotoxic properties even in patients with no deficit in kidney function.[32] Dehydration is a common risk factor in ibuprofen-induced renal injury, and as such much research has taken place regarding NSAIDs and kidney function in populations more vulnerable to dehydration, such as children with renal comorbidities or endurance athletes. A double-blind placebo-controlled trial in a population of ultramarathon participants showed an increased rate of acute kidney injury in those who took ibuprofen, with a number needed to harm of 5.5.[33] Consideration of a patient’s renal function is necessary when weighing treatment with ibuprofen or other NSAIDs.

Rashes are also a known adverse effect of ibuprofen usage, usually due to drug hypersensitivity or skin irritation via topical administration. A rash may also be part of a more severe syndrome caused by ibuprofen use, such as anaphylaxis or drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome. A case in 2016 reported a rare instance of DRESS syndrome, which causes skin, liver, and hematologic abnormalities, with ibuprofen use in a pediatric patient. DRESS syndrome is known to result more commonly with anticonvulsants, sulfa derivatives, and antimicrobials, and the number of known cases related to ibuprofen is limited. The etiology of DRESS syndrome is also unknown, with theories focusing on hypersensitivity to toxic metabolites or pathology involving human herpesvirus-6 currently postulated.[34] Other cases have existed in the literature of similar severe drug reactions involving ibuprofen or other NSAIDs; another case report in 2014 detailed a patient who developed a drug-induced liver injury with multiform exudative erythema after ingestion of an over-the-counter medication containing ibuprofen for 20 days.[35]

The association between hypertension and NSAID use has undergone research previously. A cross-sectional study of an elderly population in 1993 showed NSAID usage to be an independent risk factor in the development of hypertension in this population.[36] Studies since then have pursued more knowledge on NSAIDs in the context of hypertension, such as investigating for comparative differences between NSAIDs. A retrospective cohort study in 2012 showed an association with a small increase in systolic blood pressure with NSAIDs compared to acetaminophen use, particularly ibuprofen. This effect was negligible, though, in patients prescribed diuretics or multiple antihypertensives.[37]

Intravenous ibuprofen in the treatment of patent ductus arteriosus (PDA) has shown an increased incidence of hyperbilirubinemia, as well as bilirubin-displacement due to the high protein binding of the medication.[38]

Ibuprofen use is contraindicated in patients with a known history of hypersensitivity or allergic reactions to the drug itself, other NSAIDs, or aspirin. Numerous case studies detail ibuprofen as a precipitant of disease after usage.[34][35] NSAIDs as a class are among the most frequently associated with hypersensitivity reactions for both adult and pediatric populations, with the most frequent diagnoses being urticaria/angioedema caused by cross-intolerance to other drug classes, namely quinolones and amoxicillin-clavulanic acid.[39] Research done on NSAID-induced hypersensitivity reactions in the pediatric population showed similar prevalence but differences in the clinical phenotypes. Oral provocation testing is still the gold standard for diagnosis of NSAID hypersensitivity, and safe alternatives for cross-intolerant children and adolescents exist, including tolmetin, etoricoxib, paracetamol, and nimesulide.[40]

In preterm neonates, ibuprofen lysine IV formulation is contraindicated in those with congenital heart diseases that require patency of the PDA, active bleeding, thrombocytopenia, renal impairment, coagulation defects, and proven or suspected necrotizing enterocolitis. Aside from this, ibuprofen use has been shown not to have any increased adverse effects when used in infants younger than six months and is still indicated for use in pediatric populations outside of these contraindications.[39]

In Canada, ibuprofen has contraindications listed on drug labels for additional conditions, including active GI or cerebrovascular bleeding, uncontrolled heart failure, lupus, renal impairment, and hepatic impairment or disease.