Gut 1999;44:347–352 347 Ciprofloxacin decreases the rate of ethanol elimination in humans Gut: first published as 10.1136/gut.44.3.347 on 1 March 1999. Downloaded from J Tillonen, N Homann, M Rautio, H Jousimies-Somer, M Salaspuro Abstract Liver catalase can oxidise ethanol in vitro, but Background—Extrahepatic ethanol me- under physiological conditions catalase ap- tabolism is postulated to take place via pears to play only a minor role in ethanol microbial oxidation in the colon, mediated metabolism.2 by aerobic and facultative anaerobic bac- Extrahepatic elimination of ethanol does, teria. however, also occur. To a smaller extent, etha- Aims—To evaluate the role of microbial nol is oxidised to acetaldehyde in other tissues ethanol oxidation in the total elimination possessing ADH activity, such as the stomach, rate of ethanol in humans by reducing gut small intestine, colon, kidneys, and lungs.4 In flora with ciprofloxacin. rats, the extrahepatic gastrointestinal metabo- Methods—Ethanol was administered in- lism of circulating ethanol has been shown to travenously at the beginning and end of a be up to 30% of that in the liver.5 Furthermore, one week period to eight male volunteers. in patients with cirrhosis of the liver, extrahe- Between ethanol doses volunteers re- patic elimination has been estimated to consti- ceived 750 mg ciprofloxacin twice daily. tute about 40% of the total ethanol 6 Results—A highly significant (p=0.001) elimination. reduction in the ethanol elimination rate Due to its high water solubility, ethanol lev- (EER) was detected after ciprofloxacin els inside the terminal ileum7 and colon8 are medication. Mean (SEM) EER was 107.0 equal to those of the blood. We have recently (5.3) and 96.9 (4.8) mg/kg/h before and shown in experimental animals that ethanol after ciprofloxacin, respectively. Faecal can be oxidised via the aerobic and facultative 9 Enterobacteriaceae and Enterococcus sp. anaerobic bacteria in the large intestine. Most were totally absent after medication, and of the luminal bacteria are anaerobic, and faecal acetaldehyde production capacity without oxygen they are capable of producing 10 was significantly (p<0.05) decreased from energy through fermentation. In alcoholic 0.91 (0.15) to 0.39 (0.08) nmol/min/mg fermentation the end product is ethanol, which http://gut.bmj.com/ protein. Mean faecal alcohol dehydroge- is derived from acetaldehyde in a reductive 11 nase (ADH) activity was significantly reaction mediated by bacterial ADH. How- (p<0.05) decreased after medication, but ever, oxygen diVuses through the colonic ciprofloxacin did not inhibit human he- mucosa, and, accordingly, the human gut con- patic ADH activity in vitro. tains a mucosa associated microflora in which the number of aerobic and facultative anaero- Conclusions—Ciprofloxacin treatment 12 decreased the ethanol elimination rate by bic bacteria is almost comparable to that of on September 25, 2021 by guest. Protected copyright. 9.4%, with a concomitant decrease in anaerobic bacteria. Under these conditions and intestinal aerobic and facultative anaero- in the presence of exogenous ethanol, the ADH bic bacteria, faecal ADH activity, and mediated bacterial reaction can oxidise ethanol acetaldehyde production. As ciprofloxacin to acetaldehyde in a reaction in which nicotina- mide adenine dinucleotide (NAD) acts as an has no eVect on liver blood flow, hepatic 13 ADH activity, or cytochrome CYP2E1 electron acceptor. Microbial catalases, in the presence of H2O2, can also oxidise ethanol to activity, these eVects are probably caused 14 by the reduction in intestinal flora. acetaldehyde. Research Unit of (Gut 1999;44:347–352) Ciprofloxacin possesses excellent in vitro Alcohol Diseases, and in vivo antibacterial activities against most University of Helsinki, Keywords: ciprofloxacin; ethanol; colonic bacteria; aerobic and facultative anaerobic bacteria, Tukholmankatu 8 F, metabolism; alcohol dehydrogenase; acetaldehyde including Enterobacteriaceae.15 16 Further- 00290 Helsinki, Finland more, ciprofloxacin is partly eliminated J Tillonen 17 N Homann through the intestinal wall, and the concen- M Salaspuro The most important route of ethanol elimina- trations of ciprofloxacin in the faeces and tion is its metabolism in the liver, with small intestinal mucosa are higher than the corre- Anaerobe Reference amounts excreted in the breath (0.7%), urine sponding serum levels.18 This transintestinal Laboratory, National (0.3%), and sweat (0.1%).1 Three principal elimination pattern may explain the ability of Public Health hepatic enzyme systems are involved: alcohol this drug to modify the colonic flora. Institute, Helsinki, dehydrogenase (ADH), the microsomal etha- Treatment with ciprofloxacin was recently Finland 2 M Rautio nol oxidising system (MEOS), and catalase. It shown to reduce the rate of ethanol elimination H Jousimies-Somer is generally agreed that the major part of etha- by 9% in rats, and this was associated with a nol is metabolised by cytosolic ADH.2 The Correspondence to: contribution of the MEOS to ethanol elimina- Professor Salaspuro. Abbreviations used in this paper: ADH, alcohol tion is limited, and only a minor part (1–5%) of dehydrogenase; EER, ethanol elimination rate; GOX, Accepted for publication the total metabolism in vivo is carried out by glucose oxidase; MEOS, microsomal ethanol oxidising 23 September 1998 the cytochrome P450 dependent MEOS.3 system; NAD, nicotinamide adenine dinucleotide. 348 Tillonen, Homann, Rautio, et al reduction in faecal aerobic flora and faecal Faecal samples were collected before and after ADH activity.19 The aim of the present study medication, and samples were frozen to −80°C was to evaluate the role of microbial ethanol within six hours. oxidation in the total elimination of ethanol in Gut: first published as 10.1136/gut.44.3.347 on 1 March 1999. Downloaded from man by reducing human gut flora with BACTERIAL ANALYSIS ciprofloxacin. The second aim was to study The faecal samples were thawed, and1gof possible changes in faecal flora and faecal each specimen was suspended and serially enzyme activities participating in both ethanol diluted (10-fold) from 10−1 to 10−6 in peptone oxidation and acetaldehyde production before yeast extract broth. Undiluted sample and a 10 and after administration of ciprofloxacin for µl aliquot of the appropriate dilutions were one week. inoculated and spread on several selective and non-selective agar media for the enumeration Materials and methods and isolation of total counts and main groups SUBJECTS of aerobic and anaerobic bacteria and yeasts. After approval by the Ethical Committee at the The aerobic plates were incubated at 35°Cin University Central Hospital of Helsinki, eight an atmosphere containing 5% CO2 for up to healthy men, with an age range of 21–31 years five days; anaerobic plates were incubated in participated in the in vivo studies. Mean body anaerobic jars filled with the evacuation weight was 78 (3) kg, and body mass index replacement method with mixed gas (90% N2, 2 23.8 (0.4) kg/m . None of the subjects had 5% CO2,5%H2) for seven days for the first received any antibiotics for four weeks preced- inspection and up to 14 days for the final ing the study or was using any other drugs dur- inspection. The sensitivity of this method was ing the study days. One of the subjects was a 3000 colony forming units (cfu)/g faeces. The light smoker. All were moderate consumers of bacteria were enumerated and identified by alcohol, with a weekly average consumption of established methods.20 21 70 g or less of ethanol. All participants were told to refrain from ethanol for at least 36 hours FAECAL ACETALDEHYDE PRODUCTION before the study. To measure acetaldehyde production capacity, faecal samples were lyophilised for 24 hours STUDY DESIGN (Micromodulyo 1.5K Freeze Dryer, RV5 A paired design in which each subject served as Rotatory Vane Pump, Edwards High Vacuum his own control was used (open, non- Int., UK). Thereafter dried faecal samples were randomised, no placebo control). Two study dissolved in 0.1 M potassium phosphate days were separated by a one week interval. (KPO) buVer (pH 7.4) at a concentration of 20 The volunteers were admitted to the University mg/ml. To obtain supernatant, the solution was Central Hospital of Helsinki, and all studies first homogenised (10 × 5 seconds, 1200 min−1; http://gut.bmj.com/ started between 8 00 and 9 00 am. Two intra- Potter S Homogenizer, B. Braun Melsungen venous lines (Viggo, 1.22 mm/18GL32mm, AG, Germany) and then sonicated (8 × 20 sec- BOC Ohmeda AB, Helsingborg, Sweden) were onds, 20 kHz, Sonics & Materials, USA), placed into the antecubital veins at the surrounded by ice to avoid protein coagulation. beginning of each study day, one for the This was followed by centrifugation of the administration of ethanol and one for obtaining sonicate at 100 000 g at 5°C for 60 minutes, repeated blood samples. Ethanol (0.63 g/kg and supernatant was collected and used for body weight) was mixed in 5% glucose solution measurements. A 250 µl aliquot of supernatant on September 25, 2021 by guest. Protected copyright. at 7% concentration and was administered at a was incubated for 60 minutes in closed glass constant rate over a 30 minute period intrave- vials with 50 µl ethanol/buVer mixture (final nously. This application was chosen to avoid concentration 22 mM ethanol, 0.1 M KPO the influence of the first pass metabolism and buVer, pH 7.4) at 37°C after adding diVerent alterations in gastric motility on ethanol coenzymes. The coenzymes used were nicoti- pharmacokinetics. Eating and smoking were namide adenine dinucleotide (NAD; final con- prohibited during the study. Blood samples (3 centration in the reaction mixture 3 mM) to ml) were taken into vacutainer tubes contain- activate ADH, glucose oxidase (GOX; final ing 0.06 ml EDTA for measurement of blood concentration 0.03 µmol/min) and glucose alcohol levels by head space gas chromatogra- (final concentration 10 mM) to produce phy.