🧬 Receptor activity
| Target | Action | Affinity | Source | |
|---|---|---|---|---|
| Solute carrier family 22 member 20 | — | Ki 1100 nM | CHEMBL | TargetSolute carrier family 22 member 20 Action— AffinityKi 1100 nM SourceCHEMBL |
| Solute carrier family 22 member 6 | — | Ki 3500 nM | CHEMBL | TargetSolute carrier family 22 member 6 Action— AffinityKi 3500 nM SourceCHEMBL |
| Prostaglandin G/H synthase 2 | — | Ki 9000 nM | CHEMBL | TargetProstaglandin G/H synthase 2 Action— AffinityKi 9000 nM SourceCHEMBL |
| Prostaglandin G/H synthase 1 | — | Ki 9000 nM | CHEMBL | TargetProstaglandin G/H synthase 1 Action— AffinityKi 9000 nM SourceCHEMBL |
| Fatty acid-binding protein, liver | — | Ki 47600 nM | CHEMBL | TargetFatty acid-binding protein, liver Action— AffinityKi 47600 nM SourceCHEMBL |
| Cytochrome P450 2C9 | — | Ki 50000 nM | CHEMBL | TargetCytochrome P450 2C9 Action— AffinityKi 50000 nM SourceCHEMBL |
| Solute carrier organic anion transporter family member 1A1 | — | Ki 126000 nM | CHEMBL | TargetSolute carrier organic anion transporter family member 1A1 Action— AffinityKi 126000 nM SourceCHEMBL |
| Dihydrofolate reductase | — | Ki 560000 nM | CHEMBL | TargetDihydrofolate reductase Action— AffinityKi 560000 nM SourceCHEMBL |
| Organic anion transporter 3 | — | Ki 1170000 nM | CHEMBL | TargetOrganic anion transporter 3 Action— AffinityKi 1170000 nM SourceCHEMBL |
| Solute carrier organic anion transporter family member 1A4 | — | Ki 2430000 nM | CHEMBL | TargetSolute carrier organic anion transporter family member 1A4 Action— AffinityKi 2430000 nM SourceCHEMBL |
| Albumin | — | Ki 165958690743755.62 nM | CHEMBL | TargetAlbumin Action— AffinityKi 165958690743755.62 nM SourceCHEMBL |
Mechanism of action
The exact mechanism of action of ibuprofen is unknown. However, ibuprofen is considered an NSAID and thus it is a non-selective inhibitor of cyclooxygenase, which is an enzyme involved in prostaglandin (mediators of pain and fever) and thromboxane (stimulators of blood clotting) synthesis via the arachidonic acid pathway. Ibuprofen is a non-selective COX inhibitor and hence, it inhibits the activity of both COX-1 and COX-2. The inhibition of COX-2 activity decreases the synthesis of prostaglandins involved in mediating inflammation, pain, fever, and swelling while the inhibition of COX-1 is thought to cause some of the side effects of ibuprofen including GI ulceration.
IBUPROFEN AT 25 MG/KG IV INCREASED THE PRIMARY AND TOTAL HEMOSTATIC PLUG FORMATION TIME IN RABBIT EAR CHAMBERS WITH LASER-INDUCED INJURY. THE SAME DOSE INCREASED THE NUMBER OF CUMULATIVE EMBOLI OVER A 10 MINUTE PERIOD AFTER A LASER INJURY TO ARTERIOLES. IN DOGS, DOSES OF 10, 25, AND 50 MG/KG DID NOT ENHANCE THE RELEASE OF (125)I-LABELED FIBRIN DEGRADATION PRODUCTS FROM THE THROMBI AFTER INCUBATION IN PLASMIN, BUT THE LARGEST DOSE SIGNIFICANTLY DECREASED THE THROMBUS WEIGHT 90 AND 180 MINUTES AFTER DRUG ADMINISTRATION. THUS, IBUPROFEN HAD AN INHIBITORY EFFECT ON PLATELET FUNCTION IN VIVO AND IN LARGE DOSES DIMINISHED THE THROMBUS WEIGHT.
L-Arginine (L-arg) exhibits multiple biological properties and plays an important role in the regulation of different functions in pathological conditions. Many of these effects could be achieved on this amino acid serving as a substrate for the enzyme nitric oxide synthase (NOS). At the gastrointestinal level, recent reports revealed its protective activities involving a hyperemic response increasing the gastric blood flow. The aim of this study was to characterize the relationship between NOS activity/expression and prostaglandin changes (PGs) in rats gastric mucosa, with L-arg associated resistance to the nonsteroidal anti-inflammatory drug (NSAID) ibuprofen (IBP). The protective effect of oral L-arg (100 mg/kg body wt), administerred together with IBP (100 mg/kg body wt, per os), was evident enough 90 min after drug administration, although a significant protection persisted for more than 6 hr. Pretreatment with N(G)-nitro-L-arginine (L-NNA) (40 mg/kg body wt, intraperitoneally), a competitive inhibitor of constitutive NOS, partly altered the protection afforded by the amino acid. In contrast, no changes could be observed after inducible NOS inhibition [aminoguanidine (AG) 50 mg/Kg body wt, intraperitoneally). L-arg, plus IBP, produced a significant increase of the cyclic GMP (cGMP) response in tissue samples from rat stomach, 90 min and 6 h after drug administration. iNOS activity and mRNA expression were higher in IBP-treated rats, and no differences were observed in inducible responses in the L-arg plus IBP group. No variations in the cNOS activity and expression were found among the different groups of animals assayed. The measurement of mucosal PGE2 content confirmed that biosynthesis of the eicosanoid is maintained by L-arg for over 90 min after IBP, while a total inhibition was observed 6 hr later. The mechanisms of the L-arg protective effect on the damaged induced by IBP could be explained by the different period after drug administration. The early phase is mediated by cyclooxygenase/prostaglandins pathway (COX/PGs) although NO liberated by cNOS and the guanylate cyclase/cGMP pathway could be also relevant. The later phase implicates inhibition of the iNOS/NO response.
We previously showed the non-steroidal anti-inflammatory drug (NSAID) ibuprofen suppresses inflammation and amyloid in the APPsw (Tg2576) Tg2576 transgenic mouse. The mechanism for these effects and the impact on behavior are unknown. We now show ibuprofen's effects were not mediated by alterations in amyloid precursor protein (APP) expression or oxidative damage (carbonyls). Six months ibuprofen treatment in Tg+ females caused a decrease in open field behavior (p < 0.05), restoring values similar to Tg- mice. Reduced caspase activation per plaque provided further evidence for a neuroprotective action of ibuprofen.The impact of a shorter 3 month duration ibuprofen trial, beginning at a later age (from 14 to 17 months), was also investigated. Repeated measures ANOVA of Abeta levels (soluble and insoluble) demonstrated a significant ibuprofen treatment effect (p < 0.05). Post-hoc analysis showed that ibuprofen-dependent reductions of both soluble Abeta and Abeta42 were most marked in entorhinal cortex (p < 0.05). Although interleukin-1beta and insoluble Abeta were more effectively reduced with longer treatment, the magnitude of the effect on soluble Abeta was not dependent on treatment duration.
Trying to decrease the production of Amyloid beta (Abeta) has been envisaged as a promising approach to prevent neurodegeneration in Alzheimer's disease (AD). A chronic inflammatory reaction with activated microglia cells and astrocytes is a constant feature of AD. The participation of the immune system in the disease process is further documented in several retrospective clinical studies showing an inverse relationship between the prevalence of AD and nonsteroidal anti-inflammatory drug (NSAID) therapy. Previously, we demonstrated that the combination of the proinflammatory cytokines TNFalpha with IFNgamma induces the production of Abeta-42 and Abeta-40 in human neuronal cells. In the present study, the neuronal cell line Sk-n-sh was incubated for 12 h with the cyclooxygenase inhibitor ibuprofen and subsequently stimulated with the cytokines TNFalpha and IFNgamma. Ibuprofen treatment decreased the secretion of total Abeta in the conditioned media of cytokine stimulated cells by 50% and prevented the accumulation of Abeta-42 and Abeta-40 in detergent soluble cell extracts. Viability of neuronal cells measured by detection of apoptosis was neither influenced by ibuprofen nor by cytokine treatment. The reduction in the production of Abeta by ibuprofen was presumably due to a decreased production of betaAPP, which in contrast to the control proteins M2 pyruvate kinase, beta-tubulin and the cytokine inducible ICAM-1 was detected at low concentration in ibuprofen treated cells. The data demonstrate a possible mechanism how ibuprofen may decrease the risk and delay the onset of AD.
Pharmacodynamics
Ibuprofen has multiple actions in different inflammatory pathways involved in acute and chronic inflammation. The main effects reported in ibuprofen are related to the control of pain, fever and acute inflammation by the inhibition of the synthesis of prostanoids by COX-1 and COX-2. Pain relief is attributed to peripheral affected regions and central nervous system effects in the pain transmission mediated by the dorsal horn and higher spinothalamic tract. Some reports have tried to link the pain regulation with a possible enhancement on the synthesis of endogenous cannabinoids and action on the NMDA receptors. The effect on pain has been shown to be related to the cortically evoked potentials. The antipyretic effect is reported to be linked to the effect on the prostanoid synthesis due to the fact that the prostanoids are the main signaling mediator of pyresis in the hypothalamic-preoptic region. The use of ibuprofen in dental procedures is attributed to the local inhibition of prostanoid production as well as to anti-oedemic activity and an increase of plasma beta-endorphins. Some reports have suggested a rapid local reduction of the expression of COX-2 in dental pulp derived by the administration of ibuprofen. The administration of ibuprofen in patients with rheumatic diseases has shown to control joint symptoms. Ibuprofen is largely used in OTC products such as an agent for the management of dysmenorrhea which has been proven to reduce the amount of menstrual prostanoids and to produce a reduction in the uterine hypercontractility. As well, it has been reported to reduce significantly the fever and the pain caused by migraines. This effect is thought to be related to the effect on platelet activation and thromboxane A2 production which produces local vascular effects in the affected regions. This effect is viable as ibuprofen can enter in the central nervous system. In the investigational uses of ibuprofen, it has been reported to reduce neurodegeneration when given in low doses over a long time. On the other hand, its use in Parkinson disease is related to the importance of inflammation and oxidative stress in the pathology of this condition. The use of ibuprofen for breast cancer is related to a study that shows a decrease of 50% in the rate of breast cancer.
Pharmacokinetics
Half-life
The serum half-life of ibuprofen is 1.2-2 hours. In patients with a compromised liver function, the half-life can be prolonged to 3.1-3.4 hours.
... After oral admin ... the half-life in plasma is about 2 hr.
Absorption
It is very well absorbed orally and the peak serum concentration can be attained in 1 to 2 hours after extravascular administration. When ibuprofen is administered immediately after a meal there is a slight reduction in the absorption rate but there is no change in the extent of the absorption. When orally administered, the absorption of ibuprofen in adults is very rapidly done in the upper GI tract. The average Cmax, Tmax and AUC ranges around 20 mcg/ml, 2 h and 70 mcg.h/ml. These parameters can vary depending on the enantiomer form, route, and dose of administration.
Ibuprofen is rapidly metabolized and eliminated in the urine thus, this via accounts for more than 90% of the administered dose. It is completely eliminated in 24 hours after the last dose and almost all the administered dose goes through metabolism, representing about 99% of the eliminated dose. The biliary excretion of unchanged drug and active phase II metabolites represents 1% of the administered dose. In summary, ibuprofen is excreted as metabolites or their conjugates. The elimination of ibuprofen is not impaired by old age or the presence of renal impairment.
The apparent volume of distribution of ibuprofen is of 0.1 L/kg.
The clearance rate ranges between 3-13 L/h depending on the route of administration, enantiomer type and dosage.
Ibuprofen is rapidly absorbed after oral admin, & peak concns in plasma are observed after 15-30 min. The half-life in plasma is about 2 hr. Ibuprofen is extensively (99%) bound to plasma proteins, but the drug occupies only a fraction of the total drug-binding sites at usual concns. Ibuprofen passes slowly into the synovial spaces & may remain there in higher concn as the concns in plasma decline. In experimental animals, ibuprofen & its metabolites pass easily across the placenta. The excretion of ibuprofen is rapid & complete. More than 90% of an ingested dose is excreted in the urine as metabolites or their conjugates.
ENTERO-HEPATIC CIRCULATION OF (14)C-IBUPROFEN & ITS METABOLITES MAY HAVE OCCURRED IN DOGS RECEIVING REPEATED ORAL DOSES ... SINCE LEVELS IN BILE ... WERE 40-FOLD THOSE IN PLASMA.
Metabolism
Ibuprofen is rapidly metabolized and biotransformed in the liver to the formation of major metabolites which are the hydroxylated and carboxylated derivatives. As soon as it is absorbed, the R-enantiomer undergoes extensive enantiomeric conversion (53-65%) to the more active S-enantiomer _in vivo_ by the activity of alpha-methylacyl-CoA racemase. Ibuprofen metabolism can be divided in phase I which is represented by the hydroxylation of the isobutyl chains for the formation of 2 or 3-hydroxy derivatives followed by oxidation to 2-carboxy-ibuprofen and p-carboxy-2-propionate. These oxidative reactions are performed by the activity of the cytochrome P450 isoforms CYP 2C9, CYP 2C19 and CYP 2C8. Therefore, these enzymes participate in the oxidation of the alkyl side chain to hydroxyl and carboxyl derivatives. From this enzymes, the major catalyst in the formation of oxidative metabolites is the isoform CYP 2C9. The metabolic phase I is followed by a phase II in which the oxidative metabolites may be conjugated to glucuronide prior to excretion. This activity forms phenolic and acyl glucuronides.
TWO MAJOR METABOLIC PATHWAYS IN MAN & IN ANIMALS PROCEED BY OXIDATIVE ATTACK OF ISOBUTYL SIDE CHAIN; THEY ARE HYDROXYLATION OF THE TERTIARY CARBON TO YIELD A STABLE TERTIARY ALCOHOL, & OXIDATION OF 1 OF THE 2 GEMINAL METHYL GROUPS TO YIELD THE ACID.
IBUPROFEN GIVES 2-(4-(2-CARBOXYPROPYL)PHENYL)PROPIONIC ACID & 2-(4-(2-HYDROXY-2-METHYLPROPYL)PHENYL)PROPIONIC ACID IN MAN. /FROM TABLE/
The pharmacokinetics of oral ibuprofen following a dose of 0.8 g given 3 times a day for 14 days were studied in 7 functionally anephric patients (aged 34-66 yr) undergoing hemodialysis. No accumulation of ibuprofen plasma concns & an absence of intact ibuprofen in dialysate indicated clearance through metabolic pathways. The metabolites did accumulate significantly with mean plasma levels of 249 mcg/ml for the carboxy derivatives & 57 mcg/ml for the hydroxy derivatives of ibuprofen. However, both were detected in the dialysate. Dialysis clearance calculated by arterial & venous difference was found to agree with actual recovery in dialysate for both metabolites. Side effects were not observed in any subject.
Protein binding
Ibuprofen dosage is more than 99% bound to plasma proteins and site II of purified albumin, binding appears to be saturable and becomes non-linear at concentrations exceeding 20 mcg/ml.
External links
Fact-sheets from PsychonautWiki. Harm-reduction reference only — not medical advice.