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PubMed1996

hP, the component of log P controlling structure-activity relationships amongst non-steroidal anti-inflammatory drugs.

A range of 25 drugs and other compounds selected from published sources by strict criteria, has been used to confirm that their ability to inhibit the production of prostaglandin by mouse peritoneal macrophage does not correlate with log P but with hP, the parameter composed of only the hydrophobic contributions (atoms and groups composed of carbon, hydrogen and halogens). Other heteroatoms and physical properties can usually be ignored. Anti-inflammatory activity does not depend upon pKa or partition phenomena unless extreme, nor does it depend primarily upon the structural types within the range phenols, salicylic acids, mefenamic acids, areneacetic and profenic acids.

Animals↗
PubMed1976

Endogenous prostaglandins, adenosine 3':5'-monophosphate and sodium transport across isolated frog skin.

1. Sodium transport across isolated frog skin, as measured by the short-circuit current, was decreased by acetylsalicylic acid, mefenamic acid, paracetamol and phenylbutazone. Indomethacin (6 X 10(-6) M) had a biphasic effect on the short-circuit current: a transient increase followed by a sustained decrease. 2. The release of prostaglandin-like material from the skin was reduced by acetylsalicylic acid and indomethacin. Paracetamol caused a significant reduction in the short-circuit current response of the skin to low doses of arachidonic acid, but the response to the highest dose tested was not significantly altered. 3. Indomethacin (6 X 10(-6) M) increased the sensitivity of the skin to applied prostaglandin E1. The other prostaglandin synthetase inhibitors did not have this effect. Indomethacin (6 X 10(-6) M) also enhanced the effect of antidiuretic hormone on the short-circuit current. 4. Indomethacin (30 X 10(-6) M) increased the short-circuit current and diminished the response to applied prostaglandin E1. 5. In sulphate Ringer, theophylline increased the short-circuit current and diminished the response to prostaglandin E1. 6. Prostaglandin E1 increased the levels of cyclic AMP in frog skin and these increases preceded the increases in short-circuit current. There was a seasonal variation in the level of cyclic AMP in the skin: the levels in winter exceeded those in summer. There was also a seasonal variation in the cyclic AMP response to prostaglandin E1: the winter response was greater than that in summer. 7. Indomethacin (6 X 10(-6) M) had a biphasic effect on cyclic AMP levels in the skin, an initial increase followed by a decrease. Indomethacin also potentiated prostaglandin E1 stimulated cyclic AMP accumulation. 8. Theophylline increased cyclic AMP levels in the skin and potentiated prostaglandin E1 stimulated cyclic AMP accumulation. 9. Pre-treatment of the skin with theophylline reversed the effects of cyclic AMP on the short-circuit current and open-circuit potential. 10. It is concluded that endogenous prostaglandins help to maintain sodium transport across isolated frog skin and that the effects of E-type prostaglandins on the short-circuit current are mediated by increased cyclic AMP levels. The transient increase in short-circuit current and the increased skin sensitivity caused by indomethacin (6 X 10(-6) M) are attributed to inhibition of phosphodiesterase activity. The failure of theophylline to potentiate the short-circuit current response of the skin to prostaglandin E1 is attributed to alteration of cyclic AMP action on the skin by theophylline.

Acetaminophen↗
PubMed2006

Influences of drugs on the oxygen uptake rate and biosorption of activated sludge.

To prevent pollution of the water environment by drugs, we evaluated factors affecting the elimination of drugs by inducing reactions between the pharmaceutical chemicals originating from the drugs and activated sludge (AS) in test tubes. Of 30 pharmaceutical chemicals examined, ibuprofen (IBP) as an anti-inflammatory drug most markedly inhibited the oxygen uptake rate (OUR) of AS, and its IC50 was 172 mg/l. The IBP elimination from the wastewater was due to the significant biosorption by AS and was based on the time-response and dose-response relationships. In the pharmaceutical chemical group (1) (diclofenac Na, ketoprofen, indomethacin, salicylic acid, mefenamic acid, phenylbutazone, chlorpromazine.HCl, furosemide, tolbutamide and warfarin K) showing a relatively significant OUR inhibition (IC50, 200-500 mg/l), protein binding (75-99.7%), and the biosorption by AS also tended to be significant. In group (2) (acetaminophen, kanamycin.H2SO4, antipyrine, ethenzamide, gentamicin.H2SO4, cyclophosphamide.HCl, aminophylline, procainamide.HCl and cimetidine) showing a negligible OUR inhibition (IC50 > or =2000 mg/l), the protein binding was slight (0-74%), and biosorption by AS was also negligible. For the IBP and group (1), AS was pretreated with a certain excessive amount of each pharmaceutical chemical, and the qualitative OUR curves of the AS-synthetic sewage-II after washing showed a significant OUR inhibition immediately after the start of the reaction. Group (2), as well as the control group showed no OUR inhibition. These results suggest that the degree of OUR inhibition of AS by pharmaceutical chemicals is affected by the protein binding and the degree of biosorption. This suggests that pharmaceutical chemicals with a significant protein binding possibility can be eliminated from the wastewater by binding to AS.

Absorption↗
PubMed1977

Relaxant effect of aspirin-like drugs on isolated guinea pig tracheal chain.

The interrelation of the inhibitory effect of aspirin-like drugs on the resting tonus of tracheal chain in guinea pigs, arachidonic acid-induced contraction in rat stomach fundus strips and bradykinin-induced bronchoconstriction in guinea pigs in vivo was investigated. All the drugs tested produced a dose-related inhibitory action on the resting tonus of the tracheal chain in comparatively low doses. Diclofenac was the most potent of all the drugs and was equal in activity to isoproterenol, followed in descending order by flufenamic acid, mefenamic acid, indomethacin, ibuprofen, phenylbutazone, oxyphenbutazone and aspirin. These aspirin-like drugs also inhibited arachidonic acid-induced contraction in rat stomach fundus strips. A highly significant correlation was observed between the potency of inhibition of the arachidonic acid-induced contraction and the relaxant effect on the tracheal chain. Moreover, the drugs antagonized bradykinin-induced bronchoconstriction in guinea pigs in vivo and the order of potency roughly paralleled that of the tracheal chain. These results suggest that the aspirin-like drugs produce a reduction in resting tonus of the isolated guinea pig tracheal chain by inhibition of intramural biosynthesis of prostaglandin endoperoxides.

Animals↗
PubMed1994

Enhancement of drug absorption by antacids. An unrecognised drug interaction.

Antacids are widely used for many disorders. The potential of antacids to interact with other concomitantly ingested drugs is well recognised. These interactions usually result in reduced or delayed absorption of the affected drug. However, this is not always the case. In contrast to aluminium hydroxide, magnesium hydroxide and sodium bicarbonate can enhance the absorption of some drugs. For example, magnesium hydroxide can increase the rate and sometimes even the extent of absorption of certain nonsteroidal anti-inflammatory drugs (e.g. tolfenamic acid, mefenamic acid and ibuprofen), sulphonylurea antidiabetic agents [e.g. glipizide, glibenclamide (glyburide) and tolbutamide] and the oral anticoagulant dicoumarol (bishydroxycoumarin). These weakly acidic drugs are nonionised at gastric pH, but are sparingly water soluble. Elevation of the gastric pH by administration of magnesium hydroxide or sodium bicarbonate increases the solubility and absorption of such sparingly water soluble agents. Chelate formation may be involved in the increased absorption of dicoumarol by magnesium hydroxide. In combination antacids containing both aluminium hydroxide and magnesium hydroxide, the absorption enhancing effect of magnesium hydroxide seems to be counterbalanced by the opposing effects of aluminium hydroxide. The clinical significance of increased drug absorption is not clear. However, accelerated and enhanced absorption of analgesic drugs may be beneficial when rapid pain relief is desired. In contrast, an unexpectedly increased hypoglycaemic or anticoagulant effect may be potentially dangerous. Therefore, a knowledge of the potential effect of antacids on the absorption of other drugs is clinically important.

Absorption↗
PubMed1981

Dysmenorrhoea and prostaglandins: pharmacological and therapeutic considerations.

Primary dysmenorrhoea is characterised by painful menstrual cramps which appear to have no macroscopically identifiable pelvic pathology. 50% of postpubescent females suffer from dysmenorrhoea, and 10% are incapacitated for 1 to 3 days each month. Many of these patients have an increased synthesis of prostaglandins in their endometrial tissue with increased prostaglandin release in the menstrual fluid. The increased amount of prostaglandins induces incoordinate hyperactivity of the uterine muscle resulting in uterine ischaemia and pain. Recent clinical and laboratory studies have shown that many of the non-steroidal anti-inflammatory drugs such as ibuprofen, naproxen, flufenamic acid, mefenamic acid and indomethacin are capable of relieving primary dysmenorrhoea. These drugs are inhibitors of the prostaglandin synthetase enzymes which are necessary for prostaglandin biosynthesis. Thus, with ibuprofen it has been shown that clinical relief of the dysmenorrhoeic symptoms accompanies the reduction of menstrual fluid prostaglandins. With the oral contraceptive pill there is good relief of primary dysmenorrhoea, significant decrease in menstrual fluid prostaglandins, but no reduction in menstrual fluid volume; this suggests that the reduction in prostaglandins is secondary to the inhibition of endometrial growth and development. In some forms of secondary dysmenorrhoea elevated prostaglandin levels have been implicated. However, the evidence is less conclusive for dysmenorrhoea secondary to endometriosis and uterine myomas than for dysmenorrhoea associated with intrauterine devices. With the intrauterine device, prostaglandin synthetase inhibitors such as flufenamic acid, ibuprofen and naproxen are able not only to relieve dysmenorrhoea but also to reduce menstrual blood loss to normal levels. Thus, the use of appropriately selected prostaglandin synthetase inhibitors can offer effective relief from the miseries of some types of dysmenorrhoea with subsequent restoration of normal daily activities.

Adolescent↗
PubMed1992

[The biotransformation of NSAIDs: a common elimination site and drug interactions].

Many NSAIDs are eliminated predominantly through hepatic biotransformation in man. We have studied, in human hepatic microsomes, the role of specific cytochrome P450 isozymes in the formation of the major metabolites of oxicam (piroxicam and tenoxicam), phenylacetic (diclofenac) and propionic acid (ibuprofen) derivatives. A common isozyme (P450TB, CYP2C subfamily) controls the major elimination pathway of these NSAIDs. We have also determined, in two in vitro models of P450TB, the affinity for this isozyme of NSAIDs from other chemical classes (acetylsalicylic acid, mefenamic acid and indomethacin). All NSAIDs tested displayed a high affinity (3-300 microM) for cytochrome P450TB. Cytochrome P450TB plays a major role in the elimination of several NSAIDs with different chemical structures. NSAIDs are substrates as well as potential inhibitors of cytochrome P450TB. Their elimination can therefore be reduced by concomitant administration of known inhibitors of P450TB (antifungals, antibacterial sulfonamides, calcium channel blockers).

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1989

[The fluorometric method for analysis of some acid drugs].

By using salicylate as a working drug, pyronine was chosen from 31 dyes to form drug-dye complex. In Na2HPO4 solution, salicylate reacts with pyronine to form a complex which is soluble in chloroform. Pyronine fluoresces strongly at lambda ex 542 nm and lambda cm 566 nm and the intensity of pyronine in complex is proportional to the amount of salicylate in the complex with detection limit of 5 ng/ml. By using this method, suberogorgin, flufenamic acid, mechlofenamic acid, mefenamic acid, sodium tauroglycocholate and trichloroacetic acid may be determined with the sensitivity of 10 approximately 50 ng/ml. Salicylate in blood was determined by this method with the sensitivity of 10 ng/ml blood. Good recovery and precision were obtained.

Fluorometry↗
PubMed1993

Indomethacin/ibuprofen-like anti-inflammatory agents selectively potentiate the gamma-aminobutyric acid-antagonistic effects of several norfloxacin-like quinolone antibacterial agents on [35S]t-butylbicyclophosphorothionate binding.

Four piperazinoquinolone antibacterial drugs (norfloxacin, ciprofloxacin, enoxacin, and pipemidic acid), known to be gamma-aminobutyric acid (GABA) antagonists, fully reversed the inhibitory effect of GABA on [35S]t-butylbicyclophosphorothionate ([35S] TBPS) binding to rat brain membranes in vitro. Twelve indomethacin/ibuprofen-like arylalkanoic acid (AAA) anti-inflammatory drugs alone had no effect on [35S]TBPS binding, or on its inhibition by GABA, but potentiated the GABA-antagonistic effects of the four quinolones. Felbinac (4-biphenylacetic acid) was most potent in this respect (EC50 = 110 nM, together with 5 microM norfloxacin), followed by flurbiprofen > anirolac > metiazinic acid > tolmetin = ketoprofen = fenbufen = indomethacin > fenoprofen > ibuprofen = (+)-naproxen = sulindac. Other anti-inflammatory analgesic drugs, including aspirin, diclofenac, diflunisal, meclofenamic acid, mefenamic acid, nambumetone, phenacetin, piroxicam, and phenylbutazone, failed to potentiate the GABA-antagonistic effect of norfloxacin. Felbinac (1 microM) increased the GABA-antagonistic potencies of norfloxacin and enoxacin about 26-fold, while increasing those of ciprofloxacin and pipemidic acid 7-fold and 2.3-fold, respectively. Using subsaturating concentrations of the four quinolones, concentration-response curves for felbinac yielded EC50 values ranging from 110 nM with 5 microM norfloxacin to 1.3 microM with 100 microM pipemidic acid. Three other piperazinoquinolone antibacterial agents (amifloxacin, difloxacin, and fleroxacin) and four nonpiperazinoquinolone anti-bacterial agents (oxolinic acid, cinoxacin, nalidixic acid, and piromidic acid) were much weaker GABA antagonists and were not significantly potentiated by felbinac. All other known GABAA receptor blockers tested, including R 5135, pitrazepin, bicuculline, SR 95531, strychnine, D-tubocurarine, thebaine, securinine, theophylline, and caffeine, were not potentiated by felbinac. Our results suggest that norfloxacin and related piperazinoquinolones, acting at GABAA receptors, may induce a high affinity binding site for indomethacin/ibuprofen-like anti-inflammatory agents (the AAA site) that, when occupied, reciprocally increases the affinities of the quinolones for GABAA receptors. The AAA binding site may be a new site in the GABAA receptor complex.

4-Quinolones↗
PubMed1998

Structural requirements for the hepatotoxicity of nonsteroidal anti-inflammatory drugs in isolated rat hepatocytes.

Hepatotoxicity is one of the common side effects of nonsteroidal anti-inflammatory drugs (NSAIDs). We investigated the cytotoxicity of 18 acidic NSAIDs (3 salicylic acids, 3 anthranilic acids, 6 arylacetic acids, 6 arylpropionic acids) to freshly isolated rat hepatocytes as assessed by the NSAID-induced leakage of lactate dehydrogenase (LDH) in order to determine structural requirements for the direct hepatotoxicity of the NSAIDs. Diflunisal (salicylic acids), flufenamic acid, mefenamic acid, tolfenamic acid (anthranilic acids), diclofenac, indomethacin, acemetacin (arylacetic acids) and flurbiprofen (arylpropionic acids) caused significant LDH leakage, indicating that substituent position of a carboxyl group does not relate to the hepatotoxicity of the NSAIDs. Because the cytotoxic NSAIDs were of two types as classified by their "skeleton," diphenyl and diphenylamine, we tested the cytotoxicity of the compounds. Diphenyl did not cause LDH leakage, but diflunisal, which has the diphenyl structure, was cytotoxic. On the other hand, diphenylamine induced LDH leakage to the same degree as diclofenac, which has the diphenylamine structure. Therefore, diphenylamine itself was suggested to be responsible for the cytotoxicity of diclofenac and anthranilic acids, whereas a substituted group(s) in addition to diphenyl structure seems to be important for diflunisal cytotoxicity. All of the cytotoxic NSAIDs and diphenylamine extensively decreased hepatocellular ATP content, whereas the noncytotoxic NSAID did not, indicating that the NSAID-induced decrease in ATP, probably by their uncoupling effects on mitochondrial oxidative phosphorylation, is involved in the hepatotoxicity of the NSAIDs.

Adenosine Triphosphate↗
PubMed1991

Caffeine potentiation of mefenamic acid-induced lesions in the rat renal medulla.

The effect of caffeine given in combination with mefenamic acid on the renal medulla was examined. Sprague-Dawley rats were divided into four groups and gavage fed either vehicle suspension (control), mefenamic acid, mefenamic acid+caffeine or caffeine only for 4 months. Renal tissue taken from the corticomedullary junction was processed for electron microscopy. Ultrathin sections were cut after identification of vasa rectae on survey sections. On subsequent morphometric analysis, percentage interstitial tissue was calculated from the total area of vasa recta less the non-interstitial tissue. The median percentage of interstitial tissue in the mefenamic acid and caffeine group was 41 (range 33-50; n = 15) compared with 34 (20-48; n = 20) in mefenamic acid (P less than 0.01), 29 (15-42; n = 15) in caffeine only (P less than 0.001) and 32 (20-46; n = 18) in vehicle-treated animals (P less than 0.001). There were no significant differences between mefenamic acid alone and vehicle or caffeine-only groups or between caffeine-only and vehicle-treated controls. This suggests that caffeine potentiates the effect of the non-steroidal anti-inflammatory drug, mefenamic acid, on the rat renal medulla, resulting in a quantitative increase in the interstitial tissue between adjacent afferent and efferent vasa recta.

Animals↗
PubMed2005

Occurrence of several acidic drugs in sewage treatment plants in Switzerland and risk assessment.

The occurrence and fate of five acidic drugs (Mefenamic acid, Ibuprofen, Ketoprofen, Diclofenac and Clofibric acid) were analysed in three sewage treatment plants (STP) over 4-7 consecutive days. The results point out that the five substances were persistent in wastewater effluents after municipal wastewater treatment. At the most, half of Mefenamic acid was eliminated. Ibuprofen was well removed (80%) by one sewage treatment plant. The removal of Ibuprofen is dependent on the residence time of wastewater in the STPs. A long raining period induce an important decrease of removal of Ibuprofen and Ketoprofen. Removal rates showed a great variability according to sewage treatment plants and types of treatments (e.g. biological, physico-chemical). The concentrations of Ibuprofen, Mefenamic acid and Diclofenac were relatively high in the effluents (150-2000 ng/l), showing a potential contamination of surface water. An environmental risk assessment is presented. Mefenamic acid seems to present a risk for the aquatic environment, with a ratio PEC/PNEC higher than one.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2002

Protective role of vitamin E on mefenamic acid-induced alterations in erythrocytes.

Erythrocyte osmotic fragility (O.F.), acetylcholinesterase (AChE) activity, and the level of malonyl dialdehyde (MDA) of control, mefenamic acid treated, and mefenamic acid with vitamin E treated rats were investigated. Administration of mefenamic acid to albino rats brought about a significant increase in the osmotic fragility of red cells and a significant (p < 0.01) decrease in the activity of AChE. We have also observed increased red cell level of MDA and decreased cholesterol (Chl), hemoglobin (Hb), and reduced glutathione (GSH) content. Supplementation of vitamin E to the mefenamic acid treated rats restored the O.F., AChE activity, level of MDA, and Chl, Hb, and GSH content almost to normal. These observations suggest that mefenamic acid causes functional impairment of red cell membrane, while vitamin E shows its protective role in maintaining normal red cell functions.

Administration, Oral↗
PubMed1986

Mefenamic acid-induced bullous pemphigoid.

A 52 year old man developed bullous pemphigoid, Coombs' positive haemolytic anaemia and diarrhoea related to the use of mefenamic acid. Clinical manifestation of the bullous pemphigoid, haemolytic anaemia and diarrhoea resolved following discontinuation of the mefenamic acid. Mefenamic acid should be added to the list of agents that are known to induce bullous pemphigoid.

Anemia, Hemolytic↗
PubMed2000

Management of menorrhagia in primary care-impact on referral and hysterectomy: data from the Somerset Morbidity Project.

OBJECTIVE: To investigate the management of menorrhagia in primary care and its impact on referral and hysterectomy rates. DESIGN: Prospective observational study. SETTING: 11 general practices from the Somerset Morbidity Project. SUBJECTS: 885 women consulting their general practitioner with menorrhagia over four years. MAIN OUTCOME MEASURES: Proportions of these women investigated and treated with drugs in primary care, referred to a gynaecologist and undergoing operative procedures. The relation between investigation and prescribing in primary care and referral to and surgery in secondary care. RESULTS: Less than half of women had a vaginal examination (42%, 95% CI 39% to 45%), or a full blood count (39%, 95% CI 36% to 43%). Almost a quarter of women, 23% (95% CI 20% to 26%), received no drugs and 37% (95% CI 34% to 40%) received norethisterone. Over a third, 38% (95% CI 34% to 40%), of women were referred, and once referred 43% (95% CI 38% to 48%) of women were operated on. Women referred to a gynaecologist were significantly more likely to have received tranexamic acid and/or mefenamic acid in primary care (chi(2)=16.4, df=1, p<0.001). There were substantial between practice variations in management, for example in prescribing of tranexamic acid and/or mefenamic acid (range 16% to 72%) and referral to gynaecology (range 24% to 52%). There was a significant association between high referral and high operative rates (Spearman's correlation coefficient=0.86, p=0.001). CONCLUSIONS: Substantial differences in management exist between practices when investigating and prescribing for menorrhagia in primary care. Rates of prescribing of effective medical treatment remain low. The decision to refer a woman impacts markedly on her chances of subsequently being operated on. Effective management in primary care may not reduce referral or hysterectomy rates.

Adult↗
PubMedDate not supplied

Pyrogenic fever and blood plasma glucocorticoids after nonsteroid anti-inflammatory drugs.

Rabbits were injected with the lipopolysaccharide from E. coli (LPS) and received orally nonsteroid anti-inflammatory drugs (NSAIDs): acetylsalicylic acid, indomethacin, mefenamic acid, ibuprofen, aminophenazone, metamizole sodium, and phenylbutazone. These NSAIDs exerted antipyretic action without inhibiting the increase in the level of plasma glucocorticoids induced by LPS. This finding indicates the lack of correlation between the pyrogenic action of bacterial pyrogen and pyrogenic increase in the plasma glucocorticoid level. The investigated NSAIDs when given alone to normothermic rabbits differently affected the plasma glucocorticoid level: acetylsalicylic acid, indomethacin and ibuprofen depressed the plasma level of these hormones, mefenamic acid and phenylbutazone elevated it, and aminophenazone and metamizole sodium did not alter it significantly.

Animals↗
PubMed1976

The in-vitro adsorption of some antirheumatics on antacids.

The adsorption of sodium salicylate, salicylamide, acetylsalicylic acid, paracetamol, mefenamic acid, flufenamic acid, phenylbutazone, oxyphenbutazone, phenazone, aminophenazone, indometacin and methiazinic acid on some antacids was studied. The antacids used were magnesium trisilicate, magnesium oxide, aluminium hydroxide, bismuth oxycarbonate, calcium carbonate and kaolin. Magnesium oxide, followed by aluminium hydroxide and bismuth oxycarbonate showed a fairly high adsorptive capacity for salicylates, mefenamic acid, flufenamic acid, methiazinic acid, indometacin and to a lesser extent for phenylbutazone and oxyphenbutazone. On the other hand, magnesium trisilicate exhibited a tendency to adsorb phenazone, aminophenazone, indometacin and methiazinic acid. Kaolin was found to be a good adsorbent for anthranilic acid derivatives, indometacin and methiazinic acid. Calcium carbonate showed a weak adsorptive capacity for all drugs tested. The adsorption of phenylbutazone and salicylates on magnesium oxide, aluminium hydroxide and/or bismuth oxycarbonate obeyed the Freundlich adsorption isotherm. Elution study showed that salicylates and anthranilic acid derivatives were tenaciously held by magnesium oxide while magnesium trisilicate showed an intermediate retention power for phenazone and aminophenazone. Sodium hydrogen carbonate solution gave, in general, a higher eluting power than hydrochloric acid solution. A marked reduction in the apparent partition coefficients of all drugs tested was observed in the presence of magnesium trisilicate or aluminium hydroxide. Careful in vitro and in vivo testing of drug availability is advisable prior to the concomitant administration of antirheumatics with antacids or other adsorbents.

Adsorption↗
PubMed1983

Antiinflammatory drugs: protection of a bacterial virus as an in vitro biological measure of free radical activity.

The effects of the hydroxyl free radical (OH), the superoxide free radical (O2-) and the trichloromethyl peroxy free radical (CC13O2) on the survival of bacteriophage T2 have been studied in the absence and presence of several non-steroidal anti-inflammatory drugs (NSAID). The trichloromethylperoxy radical derived from carbon tetrachloride is considerably more effective than the hydroxyl radical in inactivating the virus: the superoxide radical has only a minor inactivating effect. All the NSAID investigated (flurbiprofen, ibuprofen, sulindac, piroxicam, benoxaprofen, mefenamic acid, diflunisal, aspirin, D-penicillamine, indomethacin and metiazinic acid) inhibit inactivation by OH. This is in agreement with the high rate constants of reaction with this radical determined using the fast reaction technique of pulse radiolysis, i.e. (k greater than 10(9) M-1 S-1). The sulphur-containing drugs, metiazinic acid, piroxicam, penicillamine and sulindac as well as the indole derivative indomethacin, protect the virus from inactivation by the model peroxy radical CC13O2 (the dose modifying factor, DMF greater than 20). In contrast, acetylsalicylic acid related drugs, such as diflunisal, the anthranilic acid derivative, mefenamic acid, and some phenylpropionic acid derivatives, such as flurbiprofen, exhibit only a very small or no protective effect (DMF less than 2). As with OH, the ability of the drugs to protect the virus from inactivation by the peroxy radical is in agreement with their corresponding rate constants of reaction determined by pulse radiolysis.

Anti-Inflammatory Agents↗