Nabumetone and flufenamic acid pose a serious risk to aquatic plants: A study with Chlamydomonas reinhardtii as a model organism.

The aquatic environment is constantly under threat due to the release of numerous pollutants. Among them, pharmaceuticals constitute a huge and diverse group. Non-steroidal anti-inflammatory drugs (NSAIDs) are increasingly found in water bodies, but knowledge about their potential toxicity is still low. In particular, there is a lack of information about their influences on aquatic plants and algae. We estimated the susceptibility of the microalgae Chlamydomonas reinhardtii to nabumetone (NBT) and flufenamic acid (FFA), focusing on photosynthesis. Due to the differences in the structures of these compounds, it was assumed that these drugs would have different toxicities to the tested green algae. The hypothesis was confirmed by determining the effective concentration values, the intensity of photosynthesis, the intensity of dark respiration, the contents of photosynthetic pigments, the fluorescence of chlorophyll a in vivo (OJIP test), and cell ultrastructure analysis. Assessment of the toxicity of the NSAIDs was extended by the calculation of an integrated biomarker response index (IBR), which is a valuable tool in ecotoxicological studies. The obtained results indicate an over six times higher toxicity of NBT compared to FFA. After analysis of the chlorophyll a fluorescence in vivo, it was found that NBT inhibited electron transport beyond the PS II. FFA, unlike NBT, lowered the intensity of photosynthesis, probably transforming some reaction centers into "silent centers", which dissipate energy as heat. The IBR estimated based on photosynthetic parameters suggests that the toxic effect of FFA results mainly from photosynthesis disruption, whereas NBT significantly affects other cellular processes. No significant alteration in the ultrastructure of treated cells could be seen, except for changes in starch grain number and autophagic vacuoles that appeared in FFA-treated cells. To the best of our knowledge, this is the first work reporting the toxic effects of NBT and FFA on unicellular green algae.

Protective effects of neutral amino acids against amphipathic drug-induced hemolysis.

Some neutral amino acids were compared for their anti-hemolytic effects with sugars which are well-known colloid-osmotic protectants. The kinetic studies in isotonic suspensions of erythrocytes indicated that the hemolysis induced by the amphipathic drug chlorpromazine (CPZ) or flufenamic acid (FA) was retarded by addition of sugars, and the degree of the anti-hemolytic effect increased with increases in molecular size. Phenylalanine (Phe), the largest among the amino acids tested, showed the greatest inhibitory effect on CPZ-induced hemolysis, but not on FA-induced hemolysis. This demonstrated that the anti-hemolytic effects of amino acids were not the result of colloid-osmotic protection. Hemolytic actions of amino acids were also examined to determine their interaction with the erythrocyte membrane, and the mechanism of their inhibitory effects against amphipathic drug-induced hemolysis was discussed.

Synthesis and anti-inflammatory and analgesic activities of 3-methyl-N-phenyl-1H-pyrazol-5-ylcarboxamides.

The anti-inflammatory and analgesic activities of a series of 3-methyl-N-phenyl-1H-pyrazol-5-ylcarboxamides were investigated and compared with flufenamic acid. The compounds were synthesized by condensation of diketopiperazines 2 with the appropriate aniline. The pharmacological tests showed that some compounds have good anti-inflammatory activity in rat paw edema induced by carrageenin and low toxicity.

[Pharmacology and toxicology of etofenamate. 1st Communication (author's transl)]. / Pharmakologie und Toxikologie von Etofenamat. I. Mitteilung.

1. The reliable antiphlogistic action of 2-(2-hydroxyethoxy)-ethyl-N-(a,a,a-trifluoro-m-tolyl)-anthranilate (etofenamate active principle of Rheumon Gel) in various experimental inflammatory models in animals is demonstrated following oral and cutaneous administration. 2. The proven inhibition of inflammatory edema by chronic administration of Rheumon gel evidences the percutaneous absorption of the active principle through the intact skin. 3. The effect of Rheumon gel sets in independently of whether the gel is applied to normal or to pathologically inflamed tissue areas. 4. Gastrointestinal mucous tolerance is better for etofenamate than for flufenamic acid, phenylbutazone and other anti-inflammatory drugs.

[Pharmacology and toxicology of etofenamate. 2]. / Pharmakologie und Toxikologie von Etofenamat. 2. Mitteilung.

1. Since the anti-inflammatory effect of 2-(2-hydroxyethoxy)-ethyl-N-(a,a,a-trifluoro-m-tolyl)anthranilate (etofenamate, TVX 485, Rheumon Gel) is occasionally stronger than that of flufenamic acid and as its toxicity is in the same range as that of the latter, a wider therapeutic margin may be expected for etofenamate in therapeutic use of Rheumon gel. 2. In subchronic oral administration, rats tolerated 22 mg/kg and dogs 100 mg/kg without any signs of toxicity. Sub-chronic cutaneous administration of Rheumon gel in pigs (2 g/kg) likewise showed no signs of toxicity. Thus, an adequate safety factor would seem to exist, bearing in mind the comparative daily dose in man of approx. 0.3 g gel/kg body weight. In histological tests oedema of kidney papillas or degeneration of papillas, respectively, could not be seen. 3. In the dose range tested, etofenamate shows no signs of teratogenic or fetotoxic effects in either rats or rabbits. 4. The evidence of the cutaneous absorption of etofenamate from Rheumon gel could be demonstrated by the biological effect in animal experiments.