EXPERIMENTAL STUDIES ЕКСПЕРИМЕНТАЛЬНІ ДОСЛІДЖЕННЯ Bardachivska K.I., Gurina N.M., Shalamay A.S., Nikolayev V.G. SORPTION ACTIVITY OF DETOXIFICATION DRUGS TOWARDS THE ESSENTIAL ANTITUBERCULOUS DRUGS (ПОГЛИНАЛЬНА АКТИВНІСТЬ ЗАСОБІВ ДЕТОКСИКАЦІЇ ВІДНОСНО ДЕЯКИХ ОСНОВНИХ ПРОТИТУБЕРКУЛЬОЗНИХ ПРЕПАРАТІВ) Institute of experimental pathology, oncology and radiobiology named after R.E., Ukraine Academy of Sciences © Bardachivska K.I., Gurina N.M., Shalamay A.S., Nikolayev V.G., 2009 Tuberculosis pharmacotherapy and prophylaxis requires active simultaneous application of the most effective and the safest therapies [1]. Modern tuberculosis therapy also provides complex use of specific antibacterial drugs and medications of various pharmacological groups. Combined chemotherapy principle allows to augment treatment efficiency as a whole. Nevertheless, it should be taken into consideration that activity of antituberculous drugs is accompanied by side effects whose manifestation can increase both in their combined use and in administration of concomitant drugs [2]. Acute and chronic hepatitis is one of the most widespread complications of antituberculous therapy in the patients [3, 4]. An excess of serum ALT level three and more times compared with the norm is a criterion of hepatotoxicity development. In patients receiving isoniazid and rifampicin without pyrazinamide experience hepatic disorders seldom enough. Including of pyrazinamide in the treatment schedule implied much higher risk of development of drug hepatitis [5, 6]. In its turn, use of isoniazid can cause neurologic disorders, and, which is more, isoniazid-associated psychosis [7] and neuropathy, especially with additional risk factors being present (HIV, alcoholism, diabetes, kidney insufficiency, undernutrition etc.). Thus, for prophylaxis and treatment of neuropathies caused by isoniazid intake, a necessity occurs to use its antidote, pyridoxine [8, 9]. Despite the essential progress in tuberculosis treatment, detoxification problem in long-term andministration of antituberculous drugs remains relevant. To reduce toxicity of antituberculous drugs as well as to eliminate complications, sorption methods are used [10–13]. In patients with hepatic function disorders that cannot be corrected with hepatotropic therapy, hemosorption on carbon sorbents allows to normalize blood biochemical values (bilirubin, AST, ALT) and improve tolerability of antituberculous drugs in patients with toxicoallergic reactions to antituberculous drugs [10]. Experiments on rats have shown that enterosorbent chitosan demonstrates hepatoprotective activity against toxic action of isoniazid and rifampicin [11]. In oral administration of carbon-mineral enterosorbent SUMS (СУМС) 1 in patients with pulmonary tuberculosis with toxic hepatic disorder, liver metabolic activity has improved, drug intolerability has reduced as well as level of primary and secondary products of lipid peroxide oxidation. At the same time, no changes of total isoniazid clearance were observed in the area under curve on the background of enterosorption [12]. A positive tendency has been detected for phytosorbent influence (fumed silicone dioxide with propolis) on immunological values in patients with newly diagnosed pulmonary tuberculosis [13]. Objectives of this study included determination of total sorption activity of enterosorbents and dietary fibers towards the essential antituberculous drugs — isoniazid, pyrazinamide and rifampicin — in in vitro experiments. Study materials and methods Study objects included: carbon enterosorbent AUT (АУТ), organsilicone enterosorbent Enterosgel and dietary fibers — microcrystal cellulose (MCC). Due to study drugs having different chemical nature, for their comparison values of marker compounds were found – vitamin B12 (marker of medium molecular weight, 1355 Da) and creatinine (low-molecular marker, 133 Da). Sorption activity towards vitamin B12 for carbon sorbent AUT was 23.10 mg/g, for Enterosgel — 3.85 mg/g, for MCC — 1.54 mg/g, towards creatinine — 19.00 mg/g, 0.86 mg/g and 0.30 mg/g, respectively. To determine common sorption activity of the above said samples of enterosorbents and dietary fibers towards antituberculosis drugs, the following substances were studied: isoniazid, pyrazinamide and rifampicin. Adsorption level of the substances was determined by the difference of their concentration before and after the contact with enterosorbents and MCC in the static regimen. Contact time was two hours. Sorption was performed in the media corresponding to gastric (рН 1.6) and pacnreatic juice (рН 6.8). Drug substance concentration was measured by spectorfotometry at the following minute lengths: isoniazid — λ=260 nm, pyrazinamide — λ =268 nm, rifampicin — λ =334 nm, corresponding to sorption maximum of these substances. Statistical data processing was conducted using Microsoft Excel programs: mean average (М) and rootmean-square error (m) was calculated. Results and their discussion As a result of the studies conducted in vitro, total sorption activity of carbon enterosorbent AUT, organsilicone enterosorbent Enterosgel and MCC dietary fibers towards antituberculous drugs — isoniazid, pyrazinamide and rifampicin. In determination of activity of the substances studied towards the drugs, substance quantities were calculated that approximately corresponded with nominal concentration of the drugs after their single administration in the models of homogenous distribution within the GIT. Data on isoniazid sorption by sorbents and dietary fibers from the media corresponding to acidity of gastric (рН 1.6) and pancreatic (рН 6.8) juice are present in Table 1. Table 1. Total activity of enterosorbents and dietary fibers towards isoniazid No. Substances studied 1 2 AUT Enterosgel Sorption in рН 1.6 mg/g 9,11 ± 0,410 0,02 ± 0,006 Sorption in рН 6.8 mg/g 9,59 ± 0,46 0,09 ± 0,01 3 MCC 0,01 ± 0,002 0,06 ± 0,01 Table 2. Total activity of enterosorbents and dietary fibers towards pyrozinamide No. Substances studied 1 2 3 AUT Enterosgel MCC Sorption in рН 1.6 mg/g 9,91 ± 0,48 0,15 ± 0,02 0,11 ± 0,01 Sorption in рН 6.8 mg/g 9,88 ± 0,42 0,13 ± 0,01 0,09 ± 0,01 Table 3. Total activity of enterosorbents and dietary fibers towards rifampicin No. Substances studied 1 2 3 AUT Enterosgel MCC Sorption in рН 1.6 mg/g 19,73 ± 0,72 1,50 ± 0,18 0,32 ± 0,02 Sorption in рН 6.8 mg/g 19,91 ± 0,71 1,13 ± 0,13 0,31 ± 0,02 As can be seen from Table 1, carbon enterosorbent AUT actively adsorbed isoniazid both in the acid medium and the neutral one. Isoniazid sorption by Enterosgel and MCC in the acid medium was almost absent. The most active adsorption was detected in the neutral medium in all the cases. Pyrazinamide sorption by all the substances studied was the highest one for the acid medium. The highest total sorption activity towards pyrazinamide was detected in enterosorbent AUT, while its enterosorption by Enterosgel and MCC was only 1-1.5% (Table 2). Data on rifampicin sorption by sorbents and dietary fibers are present in Table 3. Similar with the previous cases, AUT has demonstrated high sorption activity towards rifampicin. In comparison with carbon enterosorbents, Enterosgel adsorbed rifampicin 13-17 times less, however, these values were significantly higher for the other studies of antituberculous drugs. Moreover, in the acid medium Enterosgel was 1.3 times more active than in the neutral one. Rifampicin sorption by dietary fibers was insignificant in both media. Conclusions Carbon enterosorbent AUT has demonstrated a significantly higher sorption activity towards antituberculous drugs – isoniazid, pyrazinamide and rifampicin – in comparison with organosilicone enterosorbent Enterosgel and MCC dietary fibers both in the medium corresponding to gastric acidity and in that corresponding to pancreatic acidity. 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