Pharmacodynamics and toxicology of fenflumizole, a new non-steroidal anti-inflammatory imidazole derivative

Synthesis of deoxybenzoins from β-alkoxy styrenes and arylboronic acids via palladium-catalyzed regioselective Heck-arylation reactions

Palladium-catalyzed synthesis of deoxybenzoin derivatives from styryl ethers and arylboronic acids is reported. The reaction proceeds under mild conditions in the presence of TEMPO and provides the desired products in good to excellent yields. Simple operation, broad substrate scope, and functional group tolerance are the salient features of the developed methodology.

Synthesis and anti-phlogistic potency of some new non-proteinogenic amino acid conjugates of "Diclofenac"

In search for more potent, particularly less ulcerogenic gastritis that hopefully replace the universal NSAID "Diclofenac", (2-[(2,6-dichlorophenyl)amino]-phenylacetic acid, C.A.S. 15307-86-5), twelve new non-proteinogenic amino acid conjugates of the drug, namely that of sarcosine, beta-alanine, D-leucine and D-phenylalanine, were synthesized and biologically screened for their anti-inflammatory, analgesic and ulcerogenic activity in rats. "Diclofenac" amino acid esters (IIa-d), were synthesized via the corresponding HOSu or HOBt active esters. Alkaline hydrolysis (NaOH) followed by acidification (KHSO4) or thioamide formation (Lawsson's Reagent, C.A.S. 19172-47-5), afforded the corresponding free acids IIIa-d or the thioamides IVa-d respectively. Interestingly, in contrary to the parent "Diclofenac", the synthesized candidates (except IIId), were entirely nonulcerogenic in rats. Further, they considerably retained a generalized anti-phlogistic activity. The major "Diclofenac" irritating gastric side effect was thus eliminated. Particularly, the sarcosine conjugate IIa and its thiomimic IVa exhibit promising therapeutic perspectives.

Naproxen. A reappraisal of its pharmacology, and therapeutic use in rheumatic diseases and pain states

Naproxen is a nonsteroidal anti-inflammatory drug (NSAID) advocated for use in painful and inflammatory rheumatic and certain nonrheumatic conditions. It may be administered orally or rectally using a convenient once or twice daily regimen. Dosage adjustments are not usually required in the elderly or those with mild renal or hepatic impairment although it is probably prudent to start treatment at a low dosage and titrate upwards in such groups of patients. Numerous clinical trials have confirmed that the analgesic and anti-inflammatory efficacy of naproxen is equivalent to that of the many newer and established NSAIDs with which it has been compared. The drug is effective in many rheumatic diseases such as rheumatoid arthritis, osteoarthritis, ankylosing spondylitis and nonarticular rheumatism, in acute traumatic injury, and in the treatment of and prophylaxis against acute pain such as migraine, tension headache, postoperative pain, postpartum pain and pain associated with a variety of gynaecological procedures. Naproxen is also effective in treating the pain and associated symptoms of primary or secondary dysmenorrhoea, and decreases excessive blood loss in patients with menorrhagia. The adverse effect profile of naproxen is well established, particularly compared with that of many newer NSAIDs, and the drug is well tolerated. Thus, the efficacy and tolerability of naproxen have been clearly established over many years of clinical use, and it can therefore be considered as a first-line treatment for rheumatic diseases and various pain states.

Lack of correlation between fecal blood loss and drug-induced gastric mucosal lesions

Increased fecal blood loss was produced in healthy volunteers by the administration of two nonsteroidal anti-inflammatory drugs (NSAID), naproxen or fenflumizole. Basal as well as drug-induced gastrointestinal blood loss was measured using 51Cr erythrocyte labeling. Median rise in daily fecal blood loss was 432%. All subjects were endoscoped at the initiation and at the completion of the study. Endoscopic findings were assessed quantitatively by two observers in two different ways. All subjects but three had gastric mucosal lesions at follow-up endoscopy. There was a good correlation between the endoscopic assessments but no statistical correlation between the endoscopic assessment and the increase in fecal blood loss. The data suggest that factors other than gastric mucosal lesions have to be taken into account when investigating NSAID-induced gastrointestinal bleeding.

Antiplatelet effects of fenflumizole, a new anti-inflammatory drug, in dogs

Fenflumizole (2-(2,4-difluorophenyl)-4,5-bis(4-methoxyphenyl) imidazole) was given to dogs in a single oral dose of 3 or 10 mg/kg. The plasma concentrations of fenflumizole and the two metabolites (mono- and di-demethyl forms) attained to the peak level 1-2 hr after dosing of fenflumizole, returning to near the predose levels 8 hr after the dosing. Fenflumizole (10 mg/kg) given orally significantly inhibited collagen- and ADP-induced platelet aggregations ex vivo over 4 hr after the dosing. Fenflumizole effectively inhibited in vitro collagen-induced platelet aggregation, but failed to prevent ADP-induced aggregation. The mono-demethyl form of fenflumizole inhibited in vitro ADP- and collagen-induced aggregations, but the di-demethyl form was ineffective in inhibiting them.

Antithrombotic and ulcerogenic effects of fenflumizole, a new anti-inflammatory imidazole derivative, in rats

Fenflumizole (2-(2,4-difluorophenyl)-4,5-bis(4-methoxyphenyl) imidazole) was given to rats in a single oral dose of 30 mg/kg. The plasma concentration of fenflumizole reached a peak 2-3 hr after the dosing in non-fasted as well as fasted rats. Two metabolites (demethylation products) of fenflumizole were also detected in the plasma, but only in traces. Fenflumizole (30 and 100 mg/kg) and aspirin (100 mg/kg), given orally 2 hr prior to i.v. arachidonate (80 mg/kg), were effective in protecting the rats from death. Fenflumizole in single oral doses of 100 to 800 mg/kg dose-dependently developed erosions in the rat gastric mucosa, but was much less ulcerogenic than aspirin (3.12-200 mg/kg). Thus, fenflumizole seems to possess a potent antithrombotic activity and a relatively low gastro-ulcerogenicity in rats.

Changes in body temperature after administration of antipyretics, LSD, delta 9-THC and related agents: II

Antipyretics, in particular acetaminophen, aspirin and ibuprofen, constitute the single most important class of drugs used therapeutically for an effect on body temperature. Hallucinogens exert prominent actions on the central nervous system, and it is not surprising that, like so many other centrally-acting agents, they too often affect temperature. This compilation primarily covers the considerable amount of data published from 1981 through 1985 on the interactions of these drugs and thermoregulation, but data from many earlier papers not included in a previous compilation are also tabulated. The effects of agents not classically considered as antipyretics on temperatures of febrile subjects are also covered. The information listed includes the species used, the route of administration and dose of drug, the environmental temperature at which experiments were performed, the number of tests, the direction and magnitude of change in body temperature and remarks on special conditions, such as age or brain lesions. Also indicated is the influence of other drugs, such as antagonists, on the response to the primary agent.

High-performance liquid chromatographic assay of fenflumizole and its demethyl metabolites in biological samples

This paper describes sensitive, selective and precise methods for the assay of fenflumizole and its chromatographically verified demethyl and didemethyl metabolites in whole blood, isolated red blood cells, plasma, saliva, urine and tissue (skin and fat) from human subjects. Also conjugates of the two metabolites with glucuronic acid and sulphate were assayable. The compounds were quantitated by means of reversed-phase liquid chromatography after diethyl ether extraction, followed by fluorescence and/or electrochemical detection. The assay using fluorescence detection is quantitative down to ca. 150 pg/ml; with electrochemistry this limit was ca. 600 pg/ml and included the demethyl metabolites only. Proteinaceous materials show an extraction yield of 70-75%, whereas analytes in sample materials without proteins show yields of better than 95%. The precision at concentration levels of ca. 50 ng/ml for the parent compound and ca. 5 ng/ml for the metabolites is at most 6% (relative standard deviation) with both detection modes. The analytical procedures developed were applied after both single and repetitive administration of fenflumizole. The administration of 14C-labelled fenflumizole in the single-dose study revealed the presence in plasma and urine of as yet unknown metabolites. The in vivo retention time of 14C activity was substantially greater in the blood cells than in plasma. Measurements of 14C activity in excreta demonstrated that excretion via the faeces is the preferred route.

The influence of fenflumizole on platelet aggregation in patients with unstable angina pectoris

We have studied the antiaggregatory effect of fenflumizole, a new non-steroidal antiinflammatory imidazole derivative, in ten patients with unstable angina pectoris. We have measured the aggregation induced by arachidonic acid (AA), ADP, and collagen, and serum or plasma concentrations of beta-thromboglobulin (beta-TG), platelet factor 4 (PF-4), thromboxane B2 (TXB2), and fenflumizole before, during, and after treatment with fenflumizole in two different regimens either as 10 mg b.i.d. for four days followed by 10 mg daily for six days (Group I, n = 5), or as 20 mg b.i.d. for four days followed by 20 mg daily for six days (Group II, n = 5). The threshold concentration of AA-induced platelet aggregation increased in both groups by the first day of treatment, the mean increase being significantly higher in Group II than in Group I. There was close correlation between serum fenflumizole and the threshold concentration of AA-induced platelet aggregation (r = 0.95). A significant fall in TXB2 occurred in both groups. In group I TXB2 concentrations subsequently increased to initial values during treatment, whereas it remained significantly reduced in Group II. There were no significant changes in collagen and ADP aggregation, and beta-TG and PF-4 concentrations remained unchanged during and after the administration of fenflumizole.

Effects of a new anti-inflammatory imidazole derivative, fenflumizole, on platelet aggregation in the rabbit

The antiplatelet effect of fenflumizole, compared with aspirin or ticlopidine, was examined in in vitro, ex vivo and in vivo situations of the rabbit. Unlike ticlopidine, fenflumizole and aspirin effectively inhibited in vitro the platelet aggregation elicited by arachidonate and collagen. The activity of fenflumizole was 350 times more potent than that of aspirin. Fenflumizole (0.3-3 mg/kg) given p.o. was 4.2 and 8.1 times more potent than aspirin in inhibiting arachidonate- and collagen-induced platelet aggregations, respectively. Ticlopidine (300 mg/kg, p.o.) resulted in only weak effects on the aggregations. Fenflumizole (3 mg/kg) as well as aspirin (10 mg/kg) given p.o., unlike ticlopidine (300 mg/kg), effectively prevented the arachidonate-induced sudden death.

Pharmacokinetics of 14C-fenflumizole after intravenous administration to man

The disposition of 14C-labelled fenflumizole was studied in five healthy subjects who received 0.1 mg/kg of fenflumizole as single intravenous doses. Radioactivity was measured in whole blood, plasma, urine and feces from prior to until 168 hours after dose administration. Chemical determinations of fenflumizole and its two demethylated derivatives in plasma were made by HPLC followed by fluorescence detection. Concentrations of fenflumizole calculated from radioactivity in plasma were consistently higher than from chemical determinations, suggesting the presence of metabolites. Radioactivity in blood cells decreased more slowly than in plasma. Plasma concentrations versus time could be described by a four-compartment model, with a terminal half-life of 119 hours (median). About 50% of the dose was excreted with the faeces, and about 4% was recovered in the urine. Unchanged fenflumizole in the urine accounted for 0.0001% of the total dose. Renal clearance of radioactive material decreased at low concentrations of radioactive compound in plasma, which may indicate changes in unbound fraction of drug and metabolites, or a saturable tubular reabsorption process. The slow elimination of fenflumizole is consistent with slow release from tissues and/or enterohepatic recycling.

A double-blind placebo-controlled evaluation of fenflumizole in rheumatoid arthritis

Twenty-eight patients with active classical or definite rheumatoid arthritis were randomly allocated to treatment with fenflumizole 200 mg or 100 mg or placebo daily in a 2-week double-blind placebo-controlled study. Three patients dropped out and 25 patients completed the study. Ten patients received fenflumizole 100 mg daily, 7 patients received fenflumizole 200 mg daily and 8 patients received placebo. Clinical and laboratory assessments before and during the study revealed that in patients treated with fenflumizole, grip strength, morning stiffness and walking time improved significantly. No improvement could be seen in the placebo group. No side effects attributable to fenflumizole were observed during the study.

Changes in body temperature after administration of acetylcholine, histamine, morphine, prostaglandins and related agents: II

This survey continues a second series of compilations of data regarding changes in body temperature induced by drugs and related agents. The information listed includes the species used, the route of administration and dose of drug, the environmental temperature at which experiments were performed, the number of tests, the direction and magnitude of change in body temperature and remarks on the presence of special conditions, such as age or brain lesions. Also indicated is the influence of other drugs, such as antagonists, on the response to the primary agent. Most of the papers were published since 1979, but data from many earlier papers are also tabulated.

Single intravenous and oral doses of fenflumizole: pharmacokinetics and effects on prostanoid formation

Fenflumizole is a substituted triaryl-imidazole with anti-inflammatory activity. Its disposition in man was studied after single intravenous and oral doses to 8 healthy male volunteers. Formation of the prostanoids thromboxane B2 (TXB2) and 6-keto-prostaglandin F1 alpha (6-k-PGF1 alpha) in clotting blood was studied concomitantly. The pharmacokinetics after intravenous doses (0.1 mg/kg) could be fitted to a three compartment model and the half-lives (t 1/2) corresponding to the three phases were 2 min., 1 hour and 15 hours, respectively. The volume of distribution was 386 l and the plasma clearance 0.5 l per min. Oral doses (0.5 mg/kg) were rapidly absorbed (t 1/2 = 0.2 hr) and the following elimination from plasma had two phases with half-lives of 1 hour and 14 hours. Bioavailability was 50% due to a pronounced first-pass effect. The two metabolites mono- and didemethylfenflumizole were detected after both oral and intravenous doses and their maximum plasma concentrations occurred after 1-2 hours irrespective of the administration route. A concentration dependent depression of prostanoid formation was seen, the IC50 for TXB2 and 6-k-PGF1 alpha being 19 and 53 ng/ml respectively.

Gas--liquid chromatographic evaluation of lofemizole in biological samples for pharmacokinetic investigations. Comparison of two analytical methods

The present paper reports the analytical conditions allowing lofemizole, a new non-steroidal anti-inflammatory drug, to be evaluated in biological fluids for pharmacokinetic and bioavailability investigations. The first approach led to an N-methyl derivative of lofemizole which could be successfully analysed by gas--chromatography employing a flame-ionization detector, reaching a sensitivity of 2 micrograms/ml. The second approach led to the N-(2-chlorobenzoyl) derivative of lofemizole which was suitable for pharmacokinetic investigation using gas--liquid chromatography with electron-capture detection, and reaching a much higher sensitivity of 10 ng/ml of plasma. Recovery of the extraction, reproducibility and specificity were all satisfactory with both methods. Since the first method employing flame-ionization detection was suitable for pharmacokinetic investigations in animal species, this paper describes both methods on a comparative basis.

On the pharmacokinetics of fenflumizole, a novel antiinflammatory agent, after single oral administration to healthy subjects

The disposition of fenflumizole, a recently developed imidazole derivative which inhibits prostanoid formation, was studied after single oral administration to eight healthy subjects. Fenflumizole was given in the doses 0.1, 1 and 2 mg/kg as an aqueous suspension. Plasma concentrations within the first 24 hrs were amenable to a two-compartment open model and showed a rapid absorption with a half-life of about 0.5 hr and peak concentrations in plasma after about 1 hr. The elimination phase became dominating after about 10 hrs with a half-life of 14-15 hrs. Peak plasma levels and areas under the concentration-time curves prior to onset of the elimination phase indicated a small reduction of the bioavailability with dose on comparison of the highest and the lowest dose (P less than 0.05) but for the whole observation period of 24 hrs no dose-dependent bioavailability was revealed. The mean transit time in plasma ranged from 21 to 22 hrs. Two metabolites (demethylation products) were detected in both plasma and urine. Their plasma concentrations amounted to only about 5% of those of the parent compound, and they were rapidly eliminated. The total urinary recovery of the intact fenflumizole and the two metabolites was less than 0.1% of the given doses. The renal clearance of fenflumizole was estimated to about 0.02 ml/hr.

Effects of fenflumizole on aggregation ex vivo of human platelets and formation of thromboxane B2 and 6-keto-prostaglandin-F1 alpha

Fenflumizole (2-(2,4-difluorophenyl)-4,5-bis(4-methoxyphenyl)imidazole), a new non-steroidal anti-inflammatory drug, was given to healthy subjects in single oral doses of 0.1, 1 and 2 mg/kg. The effect of the drug was followed for up to 8 h by repeated tests of arachidonic acid-induced platelet aggregation and was related to its concomitant plasma concentration. Fenflumizole reversibly inhibited platelet aggregation and the degree of inhibition was found to be linearly correlated with the log plasma concentration. There was depression of the formation of thromboxane B2 and 6-keto-prostaglandin F1 alpha (the stable metabolites of thromboxane A2 and prostacyclin) in clotted whole blood measured by radioimmunoassay after fenflumizole 1 mg/kg. This effect was directly related to the concentration of the drug in plasma, the maximum effect being reached at fenflumizole concentrations greater than 200 ng/ml. EC50-values for inhibition of the formation of thromboxane B2 and 6-keto-prostaglandin F1 alpha were approximately 20 and 40 ng/ml, respectively. The results suggest that orally administered fenflumizole is a potent inhibitor of platelet aggregation and prostanoid formation.

Influence of fenflumizole on platelet aggregation in man

The anti-aggregatory effect of fenflumizole, a new non-steroidal anti-inflammatory imidazole derivative is described in a study in 6 healthy male volunteers, mean age 33 years. Arachidonic acid (AA), ADP, collagen aggregation, coagulation and fibrinolysis parameters were examined before, during and after treatment with oral fenflumizole first 50 mg b.i.d. for 4.5 d and then 200 mg/d for 5 days. During treatment the threshold concentration for collagen aggregation demonstrated hypo-aggregability in all subjects. No significant change was noted in ADP aggregation. AA-induced aggregation showed an increased threshold concentration during and for 7 days after fenflumizole administration. No significant change was seen in bleeding time, fibrinolysis or coagulation parameters. No side effects were observed during or after treatment. It is concluded that fenflumizole is a potent inhibitor of platelet aggregation ex vivo.

Fenflumizole: interactions with the arachidonic acid cascade

Fenflumizole (2-(2,4-difluorophenyl)-4,5-bis(4-methoxyphenyl)imidazole), a new non-steroidal anti-inflammatory agent, was investigated for interference with cyclo-oxygenase activity in vivo, ex vivo and in vitro in comparison with indomethacin (and aspirin). Fenflumizole was comparable to indomethacin ex vivo in inhibition of thromboxane (TX)A2 production in rabbit platelets and inhibition of prostaglandin (PG)I2 (approximately prostacyclin) generation in rabbit mesenteric arteries and in vivo as an inhibitor of PGE2 formation in inflammatory exudates in rats. Fenflumizole was 18 times less active than indomethacin in inhibition of PGE2 synthesis in vitro and 170 times weaker as an inhibitor of PGI2 generation in the rat stomach mucosa ex vivo. Fenflumizole was 20-50 times more potent than indomethacin in vivo in inhibition of arachidonic acid induced bronchoconstriction in guinea-pigs, in inhibition of platelet aggregation on tendons superfused with blood from rabbits and in vitro in inhibition of aggregation of human and rabbit platelets. Neither fenflumizole nor indomethacin inhibited TXA2-synthetase in vitro. Aspirin-when tested-was less potent than fenflumizole and indomethacin. It is concluded that fenflumizole is a potent cyclo-oxygenase inhibitor. The very potent activity of fenflumizole against platelet aggregation and bronchoconstriction suggests a selectivity in the mode of action. The weak inhibition of gastric PGI2 generation may account for the previously observed weak gastro-ulcerogenicity of fenflumizole.