Mechanism-based inactivation of cytochrome P450 2C9 by tienilic acid and (+/-)-suprofen: a comparison of kinetics and probe substrate selection.

In vitro experiments were conducted to compare k(inact), K(I) and inactivation efficiency (k(inact)/K(I)) of cytochrome P450 (P450) 2C9 by tienilic acid and (+/-)-suprofen using (S)-flurbiprofen, diclofenac, and (S)-warfarin as reporter substrates. Although the inactivation of P450 2C9 by tienilic acid when (S)-flurbiprofen and diclofenac were used as substrates was similar (efficiency of approximately 9 ml/min/micromol), the inactivation kinetics were characterized by a sigmoidal profile. (+/-)-Suprofen inactivation of (S)-flurbiprofen and diclofenac hydroxylation was also described by a sigmoidal profile, although inactivation was markedly less efficient (approximately 1 ml/min/micromol). In contrast, inactivation of P450 2C9-mediated (S)-warfarin 7-hydroxylation by tienilic acid and (+/-)-suprofen was best fit to a hyperbolic equation, where inactivation efficiency was moderately higher (10 ml/min/micromol) and approximately 3-fold higher (3 ml/min/micromol), respectively, relative to that of the other probe substrates, which argues for careful consideration of reporter substrate when mechanism-based inactivation of P450 2C9 is assessed in vitro. Further investigations into the increased inactivation seen with tienilic acid relative to that with (+/-)-suprofen revealed that tienilic acid is a higher affinity substrate with a spectral binding affinity constant (K(s)) of 2 microM and an in vitro half-life of 5 min compared with a K(s) of 21 microM and a 50 min in vitro half-life for (+/-)-suprofen. Lastly, a close analog of tienilic acid with the carboxylate functionality replaced by an oxirane ring was devoid of inactivation properties, which suggests that an ionic binding interaction with a positively charged residue in the P450 2C9 active site is critical for recognition and mechanism-based inactivation by these close structural analogs.

Differential suppression of menstrual fluid prostaglandin F2a, prostaglandin E2, 6-keto prostaglandin F1a and thromboxane B2 by suprofen in women with primary dysmenorrhea.

Eleven women with primary dysmenorrhea completed a randomized, double-blind, placebo-controlled, three-way cross-over study comparing 200 and 400mg suprofen. Menstrual fluid volume did not change. Mean+/-S.E.M. menstrual fluid PGF2a was significantly suppressed from 18.9+/-1.9 microg (placebo) to 10.9+/-1.7 and 9.3+/-2.1 microg with 200 and 400 mg suprofen, respectively (p=<0.005). PGE2 dropped from 7.8+/-0.9 to 4.6+/-0.8 and 4.6+/-1.1 microg (p=<0.05) and TxB2 from 17.5+/-4.3 to 7.5+/-2.9 and 3.6+/-1.3 microg (p=<0.01), respectively. 6-Keto PGF1a was significantly suppressed (2.7+/-0.4 to 1.9+/-0.5 microg, p=<0.025) with only 400 mg suprofen. Six subjects rated placebo poor and five fair to very good. In contrast, nine rated suprofen excellent to fair while two rated poor. Thus, suprofen was clinically effective but the differential suppression of prostanoids favors 200mg which spares 6-keto PGF1a.

Bioavailability and corneal anti-inflammatory effect of topical suprofen.

The bioavailability in rabbit cornea and aqueous humor of an ophthalmic formulation of suprofen, a nonsteroidal anti-inflammatory drug, was evaluated following topical administration of a single dose to the eye. The drug penetrated rapidly into the uninflamed cornea with intact epithelium; highest levels occurred during the first 30 to 45 min after instillation and decreased thereafter. The bioavailability of suprofen in cornea and aqueous humor following administration of a 1.0% concentration was twice that produced by a 0.5% concentration of the drug. Topical application of multiple doses of suprofen failed to suppress polymorphonuclear leukocyte invasion of the cornea if treatment was started after the induction of inflammation. Suprofen therapy initiated prior to the induction of corneal inflammation and maintained into the post-inflammation period did produce a significant (P less than 0.01) decrease in the numbers of PMNs that invaded the inflamed cornea. There was no significant difference (P greater than 0.05) in the corneal anti-inflammatory effect achieved by the 0.5% and 1.0% concentrations of suprofen when administered according to this regimen.

Suprofen. A review of its pharmacodynamic and pharmacokinetic properties, and analgesic efficacy.

Suprofen (sutoprofen) is a non-steroidal anti-inflammatory analgesic, closely related structurally to drugs such as ibuprofen, ketoprofen and naproxen. In patients with acute pain, single oral doses of suprofen are at least as effective as: usual therapeutic doses of aspirin; codeine alone or combined with aspirin; dextropropoxyphene alone or in various combinations; oxycodone combined with aspirin; dipyrone; pentazocine; paracetamol (acetaminophen); diflunisal; ibuprofen; indomethacin; or mefenamic acid. In chronic pain due to osteoarthritis, suprofen is as effective as usual dosages of aspirin or dextropropoxyphene during long term therapy, and as effective as diclofenac, ibuprofen, indomethacin and naproxen during short term treatment. As with other non-steroidal anti-inflammatory drugs, gastrointestinal complaints are the most frequently reported side effects, although discontinuation due to gastrointestinal effects may be necessary less frequently with suprofen than with aspirin, dextropropoxyphene or combinations of the two. Suprofen appears to be a useful alternative to mild analgesics, analgesic combinations or the older more established non-steroidal anti-inflammatory drugs in the treatment of patients with acute or chronic pain. However, further definition of its efficacy and tolerability is required, especially in comparison with newer non-steroidal anti-inflammatory analgesics.

Reduction of pupillary constriction during cataract surgery using suprofen.

The efficacy of a new nonsteroidal anti-inflammatory agent, suprofen, for reducing pupillary constriction during cataract surgery was ascertained in a double-masked, multicenter, clinical study. Prior to surgery 1.0% suprofen or a placebo was instilled; the surgeon's normal regimen of mydriatics and cycloplegics was used. Suprofen (209 patients) was far more effective than the placebo (203 patients) in maintaining a dilated pupil prior to intraocular lens (IOL) implantation (or instillation of a miotic). The mean pupillary area prior to IOL implantation was 6.3 sq mm larger (20% larger) in patients treated with suprofen than in patients receiving the placebo. The investigators' subjective evaluations of the adequacy of pupil size for IOL implantation and of the difficulty of IOL implantation favored patients treated with suprofen over those receiving the placebo.

Effect of suprofen on corneal wound healing.

We studied the effect of suprofen, a new ophthalmic nonsteroidal anti-inflammatory agent, on corneal wound healing. Nine-millimeter, central, perforating corneal wounds were made in albino rabbits and sutured with 10-0 nylon. The animals were randomly treated with balanced salt solution, suprofen vehicle, 1% suprofen, or 0.1% dexamethasone sodium phosphate administered topically for six days. On the seventh postoperative day, the sutures were removed and, in situ, the intraocular pressure was increased in a controlled manner until the wound burst. Dexamethasone applied four times a day significantly inhibited corneal wound healing, whereas suprofen given as often as hourly did not. Pretreatment with hourly administered suprofen for two days prior to surgery, in addition to the same postoperative hourly therapy, also did not significantly decrease stromal wound strength.

In vitro effects of risperidone and 9-hydroxy-risperidone on human platelet function, plasma coagulation, and fibrinolysis.

BACKGROUND: Thrombotic events have been reported with the use of antipsychotic compounds, although the incidence, predisposing factors, and biological mechanisms associated with these events in psychiatric patients are subject to debate. OBJECTIVE: The in vitro actions of risperidone and its active metabolite 9-hydroxy-risperidone (9-OH-risperidone) on human platelet function, plasma coagulation, and fibrinolysis were examined to explore whether hematologic effects might be a mechanism for thrombotic events with these compounds. METHODS: Blood was donated by healthy white male subjects who were free of medications (particularly acetylsalicylic acid and nonsteroidal anti-inflammatory compounds). Platelet shape change and adhesion/aggregation reactions to risperidone and 9-OH-risperidone induced by adenosine diphosphate (ADP), collagen, epinephrine, and 5-hydroxytryptamine (5-HT) were tested in human platelet-rich plasma. Arachidonic acid metabolism was assessed in human platelets and rat aortic rings. Plasma coagulation was tested in human platelet-poor plasma. Fibrinolysis was measured in human whole blood. RESULTS: The 12 study subjects ranged in age from 20 to 40 years (median age 30 years). At concentrations of 1 x 10(-5) mol/L (approximately 4180 ng/mL), neither risperidone nor 9-OH-risperidone induced platelet shape change or aggregation, amplified reactions to ADP, or modified platelet adhesion/aggregation induced by collagen or ADP, but they did attenuate epinephrine-induced platelet aggregation (-50% in the case of 9-OH-risperidone; P < 0.05) and 5-HT-induced platelet aggregation (drug concentrations yielding 50% inhibition of 5-HT-induced platelet aggregation, 0.5 and 0.2 ng/mL, respectively). Cyclooxygenase, thromboxane A2 synthase, 12-lipoxygenase, prostacyclin synthase, plasma coagulation, and fibrinolysis were unaffected. CONCLUSIONS: Risperidone and 9-OH-risperidone reduced epinephrine- and 5-HT-induced human platelet aggregation but did not significantly alter other measures of platelet function, plasma coagulation, or fibrinolysis in vitro.

Differential contractile responsiveness of isolated rabbit arteries from different vascular beds to cyclooxygenase inhibitors and PGI2.

The actions of three, structurally unrelated cyclooxygenase inhibitors and PGI2 on the contractile responses to electrical stimulation and to noradrenaline of strips of rabbit coeliac, ear, pulmonary, carotid, femoral arteries and the aorta were studied. Indomethacin (3 mumol/l), suprofen (0.8 mumol/l) and meclofenamic acid (0.2 mumol/l) potentiated the adrenergically induced contractions of coeliac arteries by 126-165%. The contractile responses of ear arteries were increased by these three substances by 87-91%, and the responses of pulmonary arteries by 26-33%. All of these changes were statistically significant. Prostacyclin produced a dose-related inhibition of the stimulation-induced contractions of the coeliac, ear and pulmonary arteries; its IC50 values were 10.4, 212 and 433 nmol/l, respectively. In contrast to effects in the above arteries, the evoked contractions of aortic and carotid strips were not affected by any of the prostaglandin synthesis inhibitors used; the responses of femoral vessels were reduced by all of the inhibitors (by 13-23%; P less than 0.05). Low concentrations of PGI2 did not affect the evoked contractions of aortic, carotid and femoral strips whereas higher concentrations increased baseline tone and potentiated contractions. The results indicate that there are considerable difference in the sensitivities of the arteries from different vascular beds to inhibitors of cyclooxygenase and to prostacyclin.

Swellable microparticles containing Suprofen: evaluation of in vitro release and photochemical behaviour.

Suprofen, an anti-inflammatory drug was incorporated in polymer networks based on biocompatible macromolecules, such as alpha,beta-polyasparthydrazide (PAHy) and alpha,beta-poly(N-hydroxyethyl)-DL-aspartamide (PHEA) crosslinked by glutaraldehyde or gamma-rays, respectively. Swelling tests carried out in aqueous media showed that pH value affects the swelling degree of the prepared hydrogels. In vitro release tests were performed in simulated gastrointestinal fluids (pH 1/6.8) using the pH variation method and in phosphate-buffered saline, pH 7.4. Experimental data indicated that Suprofen was released in a sustained way both from PAHy and PHEA microparticles. Further, incorporation of Suprofen in PAHy and PHEA networks provided a significant reduction of the drug photosensitizing activity, as evidenced by in vitro hemolysis tests.

Platelet-mediated vascular contractions: inhibition of the serotonergic component by ketanserin.

In vitro stimulation of washed rat platelets (2.5 X 10(10)/1) with thrombin (0.002 U/1) as well as their activation on de-endothelialized vascular preparations, produced a strong contraction of isolated rat caudal arteries. Pharmacodissection and specific measurements of various mediators (5-hydroxytryptamine, thromboxane B2, ATP) showed the platelet-mediated contraction to be mainly mediated by 5-hydroxytryptamine, either by its direct effect or through amplification of prostaglandin-effects at the level of the vessel or the platelets. Platelet-mediated vasospastic episodes were effectively reduced by ketanserin, a selective 5-HT2 receptor antagonist.

Sequence specificity of alkali-labile DNA damage photosensitized by suprofen.

On irradiation at UVB wavelengths, in aerated neutral aqueous solution, the anti-inflammatory drug suprofen (SP) photosensitizes the production of alkali-labile cleavage sites in DNA much more efficiently than direct strand breaks. It is active at submillimolar concentrations despite having no significant binding affinity for DNA. Gel sequencing studies utilizing 32P-end-labeled oligonucleotides have revealed that piperidine-sensitive lesions are formed predominantly at the positions of guanine (G) bases, with the extent of modification being UV dose- and SP concentration-dependent. Quite distinct patterns of G-specific damage are observed in single-stranded and duplex DNA molecules. The uniform attack at all G residues in single-stranded DNA, which is enhanced in D2O, is compatible with a Type-II mechanism. SP is a known generator of singlet oxygen whose participation in the reaction is supported by the effects of quenchers and scavengers. In duplex DNA, piperidine-induced cleavage occurs with high selectivity at the 5'-G of GG and (less prominently) GA doublets. This behavior is characteristic of a Type-I process involving electron transfer from DNA to photoexcited SP molecules. The ability of SP to sensitize the formation of Type-I and Type-II photo-oxidation products from 2'-deoxyguanosine attests to the feasibility of competing mechanisms in DNA.

Molecular mechanism of drug photosensitization. 7. Photocleavage of DNA sensitized by suprofen.

Ultraviolet-A irradiation of a suprofen (2-[4-2(2-thenoyl) phenyl]propionic acid) (SPF) buffered solution (pH 7.4) in the presence of supercoiled pBR322 DNA leads to single strand breaks with the formation of an open circular form and subsequent linearization of the plasmid. On the basis of agarose gel electrophoresis data of samples irradiated in an air-saturated solution or in an oxygen-modified atmosphere, and the effects of sodium azide, D20, mannitol, copper(II), superoxide dismutase, 2-H-propanol, deferoxamine and surfactants, we suggest a photosensitization mechanism involving singlet oxygen and free radicals. The higher rate of photocleavage in nitrogen compared to that in an air-saturated solution and the results obtained from oxygen consumption measurements support the hypothesis that both the type I and type II photosensitization mechanisms are operative and that oxygen quenches the excited state of the irradiated drug. The photosensitization model applied was in agreement with that previously applied to cell membrane SPF photoinduced damage. Interaction of the drug with DNA, studied through circular dichroism and fluorescence anisotropy, probably occurs through a surface binding mode. The experimental techniques used for assessing the photodamaging activity of this drug may be useful for screening of phototoxic compounds in the environment and for determining the active species involved.

Photodynamic lipid peroxidation by the photosensitizing nonsteroidal antiinflammatory drugs suprofen and tiaprofenic acid.

The photochemistry of the photosensitizing nonsteroidal antiinflammatory drugs tiaprofenic acid and suprofen involves the intermediacy of short-lived species (i.e. radicals). The data obtained in the present work strongly suggest that such intermediates may be responsible for the phototoxicity of 2-arylpropionic acids by inducing photodynamic lipid peroxidation at drug concentrations likely to be reached in the skin. This has been investigated using linoleic acid as a model lipid and determining the amount of hydroperoxides by measuring the spectrophotometric absorption at 233 nm, associated with the formation of dienic hydroperoxides. The major photoproducts of tiaprofenic acid and suprofen are derivatives bearing an ethyl side chain. Photoproducts of this type, due to the lack of polar moieties, are highly lipophilic and likely to accumulate in the lipid bilayer of cell membranes. Taking into account their ability to induce photodynamic lipid peroxidation and their marked photostability, it is conceivable that such photoproducts can participate in many catalytic cycles, playing a significant role in the mechanism of photosensitization by tiaprofenic acid and suprofen.

Effects of topical suprofen and flurbiprofen on the miosis produced by anterior chamber irrigation with cholinergic agonists.

Pretreatment with topical nonsteroidal anti-inflammatory drugs is common practice to maintain maximal pupil dilation for cataract surgery. Most surgeons also inject a cholinergic agent intracamerally for miosis after intraocular lens insertion. We evaluated the effects of topical suprofen and flurbiprofen on the miosis induced by anterior chamber irrigation with either acetylcholine or carbachol. One eye of 30 pigmented rabbits was dilated with cyclopentolate HCl and phenylephrine HCl. Three groups, each composed of ten eyes, received flurbiprofen, suprofen, or a control. In each group, five eyes received acetylcholine by anterior chamber irrigation and five received carbachol. Pupil diameters were measured with calipers before and five minutes after irrigation by an observer unaware of the treatment regimen. Irides irrigated with carbachol constricted less than those irrigated with acetylcholine (P = .016). In anterior chambers irrigated with carbachol, suprofen was associated with less miosis than either tears (P = .005) or flurbiprofen (P = .009); however, if the infusion was performed with acetylcholine, no differences between the three groups were noted (P = .44).

Mechanisms of drug photobinding to proteins: photobinding of suprofen to human serum albumin.

Photobinding of drugs to biomolecules constitutes an important early event in the onset of photoallergy. In the present work, UV irradiation of human serum albumin in the presence of either suprofen (SUP) or its major photoproduct, decarboxylated suprofen (DSUP), has been studied as a model system for drug-photosensitised protein binding. Both dark binding and binding in the presence of light were investigated since this will affect the mode, site and mechanism of drug interaction with the protein. In order to determine the binding features of SUP to albumin, competitive binding experiments were carried out using fluorescent probes specific for site I and II. Suprofen was found to selectively dark bind to site II on HSA. Photobinding of DSUP to HSA was more efficient than SUP. Parallel to this, the intrinsic tryptophan fluorescence of HSA decreased when the protein was previously irradiated in the presence of the photoactive compounds, again being DSUP more efficient compared with SUP. As fluorescence quenching involves electron transfer from the excited Trp to the ground state DSUP, it follows that the photoactive compound binding to HSA must be on (or in close proximity to) site I Trp(214) residue. It appears that photobinding of SUP is largely preceded by its photodecomposition to DSUP which, in turn, associates and photobinds to HSA.

Arachidonic acid metabolism in inflamed gingiva and its inhibition by anti-inflammatory drugs.

Prostaglandin (PG) synthetase inhibitors are tissue-selective. Therefore, the action of four nonsteroidal anti-inflammatory drugs (NSAID) was tested against PG synthesis from 14C-arachidonic acid by gingival homogenate. Suprofen and tolmetin sodium did not significantly inhibit PGs at any of the three concentration levels used (10(-7), 10(-5), 10(-3) M), whereas flurbiprofen and zomepirac sodium did significantly inhibit PG formation at millimolar concentration. The results, coupled with our previous study on indomethacin, piroxicam and ibuprofen open the way for future tests of NSAIDs in treatment of gingival inflammation and periodontal disease.

Molecular mechanism of drug photosensitization. 5. Photohemolysis sensitized by Suprofen.

Red blood cell lysis photosensitized by Suprofen (SPF) and the photolysis of the drug were investigated. The photohemolysis process occurs at a higher rate in anaerobic than aerobic conditions. The effect of additives demonstrates the involvement of free radicals and, to a lesser extent, singlet oxygen and hydroxyl radicals in the process. Photolysis of the drug at 310-390 nm in deaerated buffered solutions (pH 7.4) leads to a decarboxylation process with the formation of p-ethylphenyl 2-thienyl ketone (I), whereas in aerated solutions formation of photoproduct I and of the photoproducts p-acetylphenyl 2-thienyl ketone (II) and p-(1-hydroxyethyl)phenyl-2-thienyl ketone (III) occurs. The photodegradation products, which were separated and characterized, show a moderate lytic and photolytic activity. The rate of SPF photodegradation decreases in the presence of oxygen and increases in the presence of hydrogen donors. The overall results lead us to propose a mechanism of SPF photodegradation and a hemolysis scheme in which cell damage is provoked principally by the direct attack of drug radicals and secondarily by singlet oxygen and hydroxyl radicals.

Inhibition of pilocarpine-induced aqueous humor flare, hypotony, and miosis by topical administration of anti-inflammatory and anesthetic drugs to dogs.

OBJECTIVE: To investigate the mechanism by which pilocarpine causes increased aqueous humor (AH) flare, hypotony, and miosis in dogs. ANIMALS: 6 dogs with normal eyes. PROCEDURE: Both eyes of each dog were treated topically with a 2% solution of pilocarpine, and 1 eye of each dog was additionally treated with commercially available ophthamic solutions. Breakdown of the blood-aqueous barrier (BAB) was quantitated in each eye, using laser flaremetry to measure AH flare. Intraocular pressure and pupil size were also measured. RESULTS: Pilocarpine caused increased flare from BAB breakdown that was inhibited by the drugs tested. Inhibition (most to least) of BAB breakdown was flurbiprofen more than diclofenac, proparacaine, or suprofen, which were more than 0.125 or 1.0% prednisolone. Inhibition appeared dose-dependent and caused consensual inhibition in the contralateral eye. Intraocular pressure was decreased only in proparacaine-treated eyes and increased in eyes treated with nonsteroidal anti-inflammatory drugs (NSAID). Flurbiprofen and proparacaine were the most effective at blocking miosis. CONCLUSIONS: Pilocarpine produced a predictable, reproducible BAB breakdown in dogs. Miosis and increased AH flare were inhibited equally by proparacaine or NSAID, suggesting that these signs were caused by neuropeptide release into the AH from antidromic stimulation, which subsequently triggers prostaglandin production. Hypotony was inhibited only by anti-inflammatory drugs. CLINICAL RELEVANCE: Proparacaine in combination with pilocarpine would be the best choice for treating dogs with acute glaucoma. Topical administration of NSAID should not be used to treat dogs with acute glaucoma, because they increase intraocular pressure and negate the effects of pilocarpine.

Comparative efficacy of topically applied flurbiprofen, diclofenac, tolmetin, and suprofen for the treatment of experimentally induced blood-aqueous barrier disruption in dogs.

OBJECTIVE: To compare the relative efficacies of 4 topical nonsteroidal anti-inflammatory drugs at preventing blood-aqueous barrier (BAB) disruption in dogs. DESIGN: 1 eye of each dog was treated with 1% suspensions of diclofenac, flurbiprofen, suprofen, or tolmetin, or with control solution. After 4 applications of eyedrops at 10-minute intervals, BAB disruption was induced in the treated eye by anterior chamber paracentesis. The severity of BAB disruption was measured by anterior chamber fluorophotometry. ANIMALS: 40 ocular-normal dogs. PROCEDURE: After pretreatment with eyedrops, rapid 100-microliters nonleaking anterior chamber paracentesis was performed in 1 eye of each dog to induce BAB disruption. 1 day after paracentesis, 1 ml of 10% fluorescein sodium was injected i.v.. The amount of fluorescein entering the anterior chamber of each eye was measured 30 to 60 minutes later by use of a computerized scanning fluorophotometer. The degree of BAB disruption was determined by comparing the amount of fluorescein entering the aqueous humor of the paracentesed eye with that of the nonparacentesed eye. RESULTS: At postparacentesis day 1, the order of statistically significant BAB-stabilizing efficacy among groups was: diclofenac > flurbiprofen > suprofen > tolmetin = control solution. CONCLUSIONS: Topically applied 1% suspensions of diclofenac, flurbiprofen, and suprofen are effective at preventing BAB disruption after paracentesis in dogs, indicating their potential usefulness for treatment of prostaglandin-mediated ocular disease. 1% tolmetin is no more effective than control solution.

Dextrans--potential polymeric drug carriers for suprofen.

Dextrans are clinically useful biodegradable polysaccharide macromolecules and have been utilized as carriers for suprofen. Conjugates of suprofen were synthesized by preparing their acylimidazol derivatives which were condensed in situ with dextrans of different molecular weights (40000, 60000, 110000 and 200000). The structures of the synthesized conjugates were confirmed by IR and NMR spectroscopy. The degrees of substitution obtained were between 7.5 and 9.0%. The molecular weight was determined by the Mark-Howin Sakurada viscosity equation. Hydrolysis was studied in different buffer solutions (pH 1.2, 7.4, 9.0) and 80% human plasma (pH 7.4) and followed first order kinetics. Much faster hydrolysis was observed at pH 9.0 compared to pH 7.4 buffer solution and 80% human plasma (pH 7.4). Biological evaluation for acute and chronic anti-inflammatory activity was performed and the results were found to be comparable with the parent drug. The ulcerogenic index of conjugates showed a remarkable reduction compared to the parent suprofen.