[Experience with mefenamic acid in dentistry].
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cRNA encoding the human IsK protein was injected into Xenopus oocytes and the induced IsK channels were investigated using the two-microelectrode voltage-clamp method. Niflumic acid, mefenamic acid, flufenamic acid, and 4,4'-diisothiocyanatostilbene-2,2'- disulfonic acid, which are commonly used in Xenopus oocytes to suppress endogenous Ca(2+)-activated Cl- channels, were tested for their effects on IsK channels. At low concentrations (10 microM) all compounds increased IsK amplitude and decreased the rate of IsK deactivation. At 100 microM these compounds further decreased the rate of IsK deactivation, resulting in persistent activation of IsK, similar to what has been previously described for the action of organic cross-linkers on IsK. However, at 100 microM niflumic acid and flufenamic acid decreased the time-dependent outward current, whereas 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid and mefenamic acid caused an additional increase. When Cl- was completely substituted with gluconate, IsK had somewhat altered activation properties, but niflumic acid produced similar positive regulatory effects on IsK and shifted the voltage needed to evoke half-maximal IsK activation (V1/2) by about -20 mV. In summary, these compounds positively regulate IsK, presumably by stabilizing open IsK channels.
The synthesis of a series of mono- and disubstituted N-phenylanthranilic acids is described. Substituents on the phenyl ring include Cl, CN, OH, CF3, Br, I, CH3, OCH3, and OCF2CF2H. These compounds have been tested for their inhibitory effect on triiodothyronine (T3) uptake by H4 hepatocytes. The nonsteroidal antiinflammatory drugs flufenamic acid, mefenamic acid, and meclofenamic acid and the structurally related compounds 2,3-dimethyldiphenylamine and diclofenac were also tested. The most potent compounds were found to be, in order of decreasing activity, meclofenamic acid (2,6-Cl2,3-CH3), flufenamic acid (3-CF3), mefenamic acid (2,3-(CH3)2), and the compounds with 3,5-Cl2 and 3-OCF2CF2H substituents. The least potent compounds had 3-CN and 3-OH substituents. An analysis of quantitative structure-activity relationships (QSAR) for the series of phenylanthranilic acids showed that the inhibition of T3 uptake is highly dependent on the hydrophobicity of the compound. The relationship between uptake inhibition and the calculated octanol-water partition coefficient (clogP) was found to be parabolic, with optimum inhibitory activity found when the clogP of the phenylanthranilic acid was 5.7. It was also found that the 1-carboxylic acid group of the phenylanthranilic acids was not a prerequisite for uptake inhibition to occur, but its removal or alteration resulted in reduced inhibition.
Despite the widespread use of non-steroidal anti-inflammatory drugs (NSAIDs), the current number of reported cases of poisoning is small. However, with the introduction of 'over-the-counter' preparations of NSAIDs in some countries (e.g. ibuprofen in the UK and USA) an increased incidence of acute poisoning from this group of drugs can be expected. Conventionally, NSAIDs are divided into the following groups based on their chemical structure: arylpropionic acids, indole and indene acetic acids, heteroarylacetic acids, fenamates, phenylacetic acids, pyrazolones and oxicams. Unless NSAIDs are ingested in substantial overdose, acute poisoning with these agents does not usually result in significant morbidity or mortality. In most cases the clinical features are mild and confined to the gastrointestinal and central nervous systems, though acute renal failure, hepatic dysfunction, respiratory depression, coma, convulsions, cardiovascular collapse and cardiac arrest may complicate severe poisoning. Arylpropionic acid derivatives were thought initially to have a low order of toxicity in overdose but, in addition to anticipated gastrointestinal symptoms, headache, tinnitus, hyperventilation, sinus tachycardia, hypoprothrombinaemia, haematuria, proteinuria and acute renal failure have been described. In addition, drowsiness, coma, nystagmus, diplopia, hypothermia, hypotension, respiratory depression and cardiac arrest have been reported in severe cases of poisoning. Oxyphenbutazone and phenylbutazone are considerably more toxic in overdose. Complications of severe poisoning include coma, convulsions, hepatic dysfunction, acute renal failure, sodium and water retention, haematuria, cardiovascular collapse, respiratory alkalosis, metabolic acidosis, hypoprothrombinaemia and thrombocytopenia. In contrast, indomethacin appears to be much less toxic. In addition to gastrointestinal symptoms, indomethacin taken in overdose induces headache, tinnitus, dizziness, lethargy, drowsiness, confusion, disorientation and restlessness. Only 1 case of acute sulindac poisoning has been reported in the literature. A 16-year-old boy was admitted with hypokalaemia (2.2 mmol/L), transient granulocytosis and 'scanty' haematemesis after ingesting 12 g sulindac. No case of acute tolmetin poisoning have been reported. The fenamates (flufenamic acid, meclofenamic acid, mefenamic acid, tolfenamic acid) are, with the exception of mefenamic acid, not as widely prescribed as other groups of NSAIDs. In overdose, mefenamic acid may result in nausea, vomiting, diarrhoea, muscle twitching, convulsions and coma.(ABSTRACT TRUNCATED AT 400 WORDS)
The effect of non-steroidal anti-inflammatory drugs (NSAIDs) on the electrical properties of primary cultures of dog tracheal epithelium has been studied. The cells used were grown with an air interface in a serum-free medium on membranes coated with human placental collagen. When mounted in Ussing chambers at 37 degrees C, mean values for the baseline short circuit current (Isc) and the transepithelial resistance of 65 tissue specimens from 18 dogs were 24.0 +/- 3.2 microA/cm2 and 458 +/- 128 omega.cm2, respectively. These tissues had been pretreated with amiloride to abolish active Na+ absorption. Under these conditions, the Isc value serves as a measure of active Cl- secretion. The results of this study revealed that the Isc across a cultured monolayer of trachea was attenuated by the tested NSAIDs, indomethacin, fulfenamic acid, mefenamic acid, aspirin, and acetaminophen, with Ki's that ranged from 6.0 x 10(-5) to 2.51 x 10(-3) M. Salicylic acid had no effect on baseline Isc. The Isc sensitivity sequence to the Cl- channel inhibitors tested was: fulfenamic acid >> indomethacin > mefenamic acid >> aspirin > acetaminophen > salicylic acid. The NSAIDs also significantly inhibited both the transient, Ca(2+)-dependent and the sustained, cAMP-dependent increases in Isc elicited by isoproterenol. Thus, the tested NSAIDs appeared to have an effect on the electrical properties of the cells. A similar effect of NSAIDs on ion transport across the human airway epithelium may help to reduce airway fluid secretion.
PURPOSE: In this paper we seek to verify the differences in dissolution behavior between class I and class II drugs and to evaluate the suitability of two new physiologically based media, of Simulated Gastric Fluid (SGF) and of milk for their ability to forecast trends in the in vivo performance of class II compounds and their formulations. METHODS: Dissolution behavior of two class I drugs, i.e. acetaminophen and metoprolol, and of three class II drugs, i.e. danazol, mefenamic acid and ketoconazole, was studied with USP Apparatus 2 in water, SGF, milk, Simulated Intestinal Fluid without pancreatin (SIFsp) and in two media simulating the small intestinal contents in the fed (FeSSIF) and fasted (FaSSIF) states, respectively. RESULTS: Class I powders dissolved rapidly in all media tested. Acetaminophen dissolution in milk was slow from one tablet formulation, in all other cases dissolution was more than 85% complete in 15 minutes. The dissolution rate of metoprolol was shown to be dependent on formulation and manufacturing method, and one of the three tablet formulations did not meet compendial specifications (80%/30 minutes). Dissolution behavior of class II drugs was greatly affected by choice of medium. Dissolution from a capsule formulation of danazol proved to be dependent on the concentration of solubilizing agents, with a the 30-fold increase in percentage dissolved within 90 minutes upon changing from aqueous media without surfactants to FaSSIF. Use of FeSSIF or milk as the dissolution medium resulted in an even greater increase in percentage dissolved, 100 and 180-fold respectively. Dissolution of the weak acid mefenamic acid from a capsule formulation is dependent on both pH and bile salt concentration, which leads to an offset between increased bile salt concentration and lower pH in the fed state compared to the fasted state medium. The weak base ketoconazole showed complete dissolution from a tablet formulation in Simulated Gastric Fluid without pepsin (SGFsp) within 30 minutes, 70% dissolution in 2 hours under fed state simulated upper jejunal conditions but only 6% dissolution in 2 hours under fasted state conditions. CONCLUSIONS: As predicted, dissolution of class II drugs proved to be in general much more dependent on the medium than class I drugs. With the array of compendial and physiological media available, it should be possible to design a suitable set of tests to predict the in vivo dissolution of both class I and II drugs from immediate release formulations.
We investigated transport systems for tri-iodothyronine (T(3)) and thyroxine (T(4)) in the human choriocarcinoma cell line, JAR, using a range of structurally similar compounds to determine whether these thyroid hormones are transported by common or different mechanisms. Saturable T(3) but not saturable T(4) uptake was inhibited by a wide range of aromatic compounds (nitrendipine, nifedipine, verapamil, meclofenamic acid, mefenamic acid, diazepam, phenytoin). Nitrendipine and diazepam were the most effective inhibitors of saturable thyroid hormone uptake. Nitrendipine decreased the K(m) for T(4) uptake from a control value of around 500 nM to around 300 nM (n=6). In contrast, the K(m) for T(3) uptake was increased from a control value of around 300 nM to around 750 nM (n=4). Diazepam had similar effects. This divergent shift in affinity for the uptake of T(3) and T(4) suggested that separate uptake systems exist for these two thyroid hormones. This provides evidence for at least two transporters mediating uptake of T(3) and T(4) in JAR cells: a specific T(4) transporter that does not interact with T(3) or structurally similar compounds; and a shared iodothyronine transporter that interacts with T(3), T(4), nitrendipine and diazepam.
In the guinea-pig, N-(2,3-xylyl)anthranilic acid (mefenamic acid) and N-(alpha,alpha,alpha-trifluoro-m-tolyl)anthranilic acid (flufenamic acid), two new anti-inflammatory agents, antagonize bronchoconstriction, but not hypotension, produced by kinins. They do not reduce bronchoconstrictor responses to acetylcholine, histamine or 5-hydroxytryptamine. The antibradykinin potencies of mefenamic and flufenamic acids approximately equal that of acetylsalicylic acid when given intravenously and of phenylbutazone when given into the duodenum. After administration of mefenamic and flufenamic acids, the bronchoconstrictor response can be restored by higher doses of bradykinin. The quantitative relationship between the intravenous dose of sodium mefenamate or flufenamate and the dose of bradykinin needed to surmount either antagonist in bronchial muscle fulfils the requirements for competitive antagonism. Antagonism by calcium acetylsalicylate can also be surmounted with higher doses of bradykinin, but in this instance the relationship of antagonist to agonist fulfils requirements for competitive antagonism only at the lower part of the dose range.
Four cases of acute proctocolitis associated with non-steroidal anti-inflammatory drug therapy are presented. The drugs implicated were flufenamic acid, mefenamic acid, naproxen and ibuprofen. After resolution of symptoms and signs of proctocolitis three of the four patients were subsequently rechallenged with the implicated drug: in each there was a rapid relapse.
1. The inhibition of the human liver phenol sulphotransferase (HL-PST) and catechol sulphotransferase (HL-CST) by five fenamates has been studied and the activities of HL-PST and HL-CST were measured with 4-nitrophenol and dopamine as substrates, respectively. 2. The IC50 for inhibition of HL-PST were 0.02 microM (mefenamic acid); 0.12 microM (tolfenamic acid); 0.28 microM (niflumic acid); 0.87 microM (meclofenamic acid) and 1.50 microM (flufenamic acid). 3. HL-CST was less susceptible than HL-PST to the inhibition by fenamates and the IC50 for HL-CST were 36 microM (tolfenamic acid); 70 microM (flufenamic acid); 76 microM (mefenamic acid); 180 microM (niflumic acid) and 185 microM (meclofenamic acid). 4. The ratios of the IC50 for HL-CST:HL-PST were drug-dependent and ranged from 47 (flufenamic acid) to 3800 (mefenamic acid). Mefenamic acid is a relatively potent and selective inhibitor of HL-PST. 5. The IC50 for HL-PST obtained with mefenamic acid was three orders of magnitude lower than the peak plasma concentration of this drug after an oral dose of 0.5 g. Accordingly, mefenamic acid should impair sulphation in vivo.
When the steady-state concentrations of peroxide in prostaglandin H synthase assay systems was lowered by added glutathione peroxidase, several agents (meclofenamic acid, mefenamic acid, acetamidophenol and phenylbutazone) became more potent inhibitors of the prostaglandin-forming cyclooxygenase reaction. Paradoxically, these agents stimulated oxygen incorporation in the absence of added peroxidase. On the other hand, dithiothreitol, ibuprofen, flurbiprofen and indomethacin all inhibited the reaction in a dose-dependent manner, and their inhibitory potencies were unaffected by the action of glutathione peroxidase. Aspirin, dl-gamma-tocopherol and salicylic acid were not inhibitory (without preincubation) under the assay conditions employed in this study. The findings demonstrate that the potencies of some anti-inflammatory agents may be diminished by high local peroxide concentrations.
A method was developed for assessing non-steroidal anti-inflammatory compounds for their potency in blocking parturition, and prolonging gestation, in the rat. This consisted of injecting compounds into groups of 10 to 13 rat dams twice daily from Day 18 through Day 22 of pregnancy, and comparing the treated dams with appropriate controls on Day 23. The rate of blocked parturition appeared to be positively related to dose of non-steroidal anti-inflammatory agent and, therefore, this model and end-point appeared to be useful for assessing different non-steroidal anti-inflammatory compounds for potency. Among the twenty-seven non-steroidal anti-inflammatory agents evaluated by this method were: ibuprofen, phenylbutazone, tolmetin, flufenamic acid, 2(p-biphenyl) acetic acid, mefenamic acid, aspirin, fenoprofen calcium, flumazole, ketoprofen, naproxen, isoxicam, indomethacin, 2(p-biphenyl) propionic acid, 2(2'-fluoro-4-biphenyl) propionic acid, flurbiprofen, sudoxicam and piroxicam. Piroxicam, sudoxicam, flurbiprofen, 2(p-biphenyl) propionic acid and 2(2'-fluoro-4-biphenyl) propionic acid showed the greatest potency. The relationship between structure and activity and between the blocking of parturition and the inhibition of prostaglandin synthesis are discussed.
Using the standard patch clamp whole cell recording method, we assessed the pharmacological activity of four fenamate nonsteroidal anti-inflammatory drugs, meclofenamic acid, flufenamic acid, mefenamic acid and niflumic acid, on hKv2.1, a major human neuronal voltage-gated potassium channel stably expressed heterologously in Chinese hamster ovary cells. Meclofenamic acid inhibited hKv2.1 in a concentration-dependent manner whereas the other three fenamates had weaker or no effect on these channels at a concentration of 100 microM. The estimated IC50 of meclofenamic acid was 56.0 microM for hKv2.1 compared an IC50 of 155.9 microM for another human neuronal K channel (hKv1.1). Meclofenamic acid reached its maximum inhibition within 5 min of bath application and its effect was readily reversed upon wash. Kinetic analysis revealed that this drug did not alter the channel activation or deactivation time courses. Moreover, the effect of meclofenamic acid on hKv2.1 channels was not voltage-dependent. Indomethacin, another inhibitor of the cyclooxygenase that catalyses the synthesis of prostaglandin from arachidonic acid, had no effect on either hKv2.1 or hKv1.1. These results indicate that meclofenamic acid inhibits hKv2.1 more potently than hKv1.1 and it is likely that this compound acts directly on the channel proteins.
A series of novel omega-(N,N,N-trialkylammonium)alkyl ester and thioester derivatives [RCOM(CH2)nNR3+ X-, M = O or S. n = 2-6, X = I or Cl] of 11 nonsteroidal antiinflammatory carboxylic acid agents (naproxen, ketorolac, indomethacin, ibuprofen, sulindac, ketoprofen, flufenamic acid, mefenamic acid, zomepirac, etodolac, and tifurac) was prepared and evaluated for their antiinflammatory, analgesic, and gastrointestinal erosive properties. In general, each prodrug retained the antiinflammatory activity characteristic of the corresponding parent drug but exhibited moderately to greatly reduced gastrointestinal erosive properties and significantly reduced analgetic potencies. This profile is likely due to a combination of factors including the rate of hydrolysis of the esters in the stomach, gut, and plasma, changes in the locus of absorption of the prodrug or nonsteroidal antiinflammatory drug (NSAID), and altered metabolic disposition patterns resulting from these changes. The results obtained from the compounds of this series indicate that esters of this general class may offer a means to modulate both the aqueous/lipid solubility and the hydrolytic/enzymatic cleavage indices of NSAID prodrugs which potentially possess a more favorable therapeutic ratio of antiinflammatory to gastrointestinal erosive activities.
BACKGROUND: Drug eruptions are among the most common cutaneous disorders encountered by the dermatologist. Some drug eruptions, although trivial, may cause cosmetic embarrassment and fixed drug eruption (FDE) is one of them. The diagnostic hallmark is its recurrence at previously affected sites. OBJECTIVE: We evaluated 450 FDE patients to determine the causative drugs. RESULTS: The ratio of men to women was 1:1.1. The main presentation of FDE was circular hyperpigmented lesion. Less commonly FDE presented as: nonpigmenting erythema, urticaria, dermatitis, periorbital or generalized hypermelanosis. Occasionally FDE mimicked lichen planus, erythema multiforme, Stevens-Johnson syndrome, paronychia, cheilitis, psoriasis, housewife's dermatitis, melasma, lichen planus actinicus, discoid lupus erythematosus, erythema annulare centrifugum, pemphigus vulgaris, chilblains, pityriasis rosea and vulval or perianal hypermelanosis. Cotrimoxazole was the most common cause of FDE. Other drugs incriminated were tetracycline, metamizole, phenylbutazone, paracetamol, acetylsalicylic acid, mefenamic acid, metronidazole, tinidazole, chlormezanone, amoxycillin, ampicillin, erythromycin, belladonna, griseofulvin, phenobarbitone, diclofenac sodium, indomethacin, ibuprofen, diflunisal, pyrantel pamoate, clindamycin, allopurinol, orphenadrine, and albendazole. CONCLUSIONS: Cotrimoxazole was the most common cause of FDE, whereas FDE with diclofenac sodium, pyrantel pamoate, clindamycin, and albendazole were reported for the first time. FDE may have multiform presentations.
Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used as analgesic and anti-rheumatic drugs, and they are often misused. A gas chromatographic-mass spectrometric (GC-MS) screening procedure was developed for their detection in urine as part of a systematic toxicological analysis procedure for acidic drugs and poisons after extractive methylation. The compounds were separated by capillary GC and identified by computerized MS in the full-scan mode. Using mass chromatography with the ions m/z 119, 135, 139, 152, 165, 229, 244, 266, 272, and 326, the possible presence of NSAIDs and their metabolites could be indicated. The identity of positive signals in such mass chromatograms was confirmed by comparison of the peaks underlying full mass spectra with the reference spectra recorded during this study. This method allowed the detection of therapeutic concentrations of acemetacin, acetaminophen (paracetamol), acetylsalicylic acid, diclofenac, diflunisal, etodolac, fenbufen, fenoprofen, flufenamic acid, flurbiprofen, ibuprofen, indometacin, kebuzone, ketoprofen, lonazolac, meclofenamic acid, mefenamic acid, mofebutazone, naproxen, niflumic acid, phenylbutazone, suxibuzone, tiaprofenic acid, tolfenamic acid, and tolmetin in urine samples. The overall recoveries of the different NSAIDs ranged between 50 and 80% with coefficients of variation of less than 15% (n = 5), and the limits of detection of the different NSAIDs were between 10 and 50 ng/mL (S/N = 3) in the full-scan mode. Extractive methylation has proved to be a versatile method for STA of various acidic drugs, poisons, and their metabolites in urine. It has also successfully been used for plasma analysis.