Pharmacokinetics of Sulfamethoxazole and Trimethoprim During Venovenous Extracorporeal Membrane Oxygenation: A Case Report

Extracorporeal membrane oxygenation (ECMO) therapy could affect drug concentrations via adsorption onto the oxygenator and/or associated circuit. We describe a case of a 33-year-old man with severe respiratory failure due to Pneumocystis jirovecii infection on a background of recently diagnosed human immunodeficiency virus infection. He required venovenous ECMO therapy for refractory respiratory failure. Intravenous sulfamethoxazole-trimethoprim (100 and 20 mg/kg/day) was administered in a dosing regimen every 6 hours. Pre-oxygenator, post-oxygenator, and arterial blood samples were collected after antibiotic administration and were analyzed for total sulfamethoxazole and trimethoprim concentrations. The peak sulfamethoxazole and trimethoprim concentrations were 122 mg/L and 5.3 mg/L, respectively. The volume of distribution for sulfamethoxazole was 0.37 and 2.30 L/kg for trimethoprim. The clearance for sulfamethoxazole was 0.35 ml/minute/kg and for trimethoprim was 1.64 ml/minute/kg. The pharmacokinetics of sulfamethoxazole and trimethoprim appear not to be affected by ECMO therapy, and dosing adjustment may not be required.     

Studies of the pharmacokinetics and bioavailability of a new trimethoprim/sulfamethoxazole preparation in healthy volunteers

The objective of this study was to determine both the pharmacokinetic parameters and the bioavailability of a newly developed trimethoprim/sulfamethoxazole preparation (cotrimoxazole, Kepinol forte, 160 mg of trimethoprim/800 mg of sulfamethoxazole) in comparison with a reference preparation customary in trade and registered according to the AMG 1976, after single oral administration. For this purpose the test and the reference preparation were examined in a randomized 2-way crossover design (Latin square) in 12 volunteers each. Both dosage forms led to maximum plasma levels of approx. 1250 ng/ml of trimethoprim and about 40 micrograms/ml of sulfamethoxazole 1.5-2 h after application; the plasma half-lives were about 9 h for trimethoprim and around 8.5 h for sulfamethoxazole. The statistical comparison (ANOVA, confidence intervals according to Westlake, Pratt-Wilcoxon test) of the pharmacokinetic parameters found in the study resulted in bioequivalence of the newly developed trimethoprim/sulfamethoxazole preparation and the reference preparation. Furthermore, after the administration of both preparations no marked side effects worth mentioning were observed, suggesting a good and comparable clinical tolerability of the two preparations.     

Enhanced stability of sulfamethoxazole and trimethoprim against oxidation using hydroxypropyl-beta-cyclodextrin

The effect of hydroxypropyl-beta-cyclodextrin (HPbetaCD) on the chemical stability of sulfamethoxazole and trimethoprim (co-trimoxazole) under oxidation stress at 50 +/- 2 degrees C was investigated. The concentrations of sulfamethoxazole and trimethoprim in aqueous solutions (pH 5.4) containing 0, 1%, 2%, 5%, 10% and 15% w/v hydroxypropyl-beta-cyclodextrin were measured by HPLC. Both sulfamethoxazole and trimethoprim degradation appeared to follow pseudo-first order kinetics in the presence and in the absence of hydroxypropyl-beta-cyclodextrin. The observed half-lives for sulfamethoxazole and trimethoprim in 15% w/v hydroxypropyl-beta-cyclodextrin were 910 h and 609 h respectively, 11.8 and 3.4 times greater than in solutions without hydroxypropyl-beta-cyclodextrin. Using a Lineweaver-Burk equation, the half-lives for sulfamethoxazole and trimethoprim outside the complex in a solution containing 15% w/v hydroxypropyl-beta-cyclodextrin were estimated at 77 h and 193 h respectively, whereas inside the complex the half-lives were estimated at 850 h and 821 h. In terms of relative increases in stability under oxidation stress the half-lives for sulfamethoxazole and trimethoprim inside the complex were 11.0 times and 4.2 times greater than their half-lives outside the complex. In conclusion, chemical stability of sulfamethoxazole and trimethoprim in co-trimoxazole aqueous solutions under oxidation stress at 50 +/- 2 degrees C can be increased using hydroxypropyl-beta-cyclodextrin as a molecular inclusion excipient.     

The ARESC study: an international survey on the antimicrobial resistance of pathogens involved in uncomplicated urinary tract infections

The ARESC (Antimicrobial Resistance Epidemiological Survey on Cystitis) study is an international survey to investigate the prevalence and susceptibility of pathogens causing cystitis. Female patients (n = 4264) aged 18–65 years with symptoms of uncomplicated cystitis were consecutively enrolled in nine European countries as well as Brazil during 2003–2006. Pathogens were identified and their susceptibility to nine antimicrobials was determined. Escherichia coli accounted for 76.7% of isolates. Among E. coli, 10.3% of the isolates were resistant to at last three different classes of antimicrobial agents. Resistance was most common to ampicillin (48.3%), trimethoprim/sulfamethoxazole (29.4%) and nalidixic acid (18.6%). Fosfomycin, mecillinam and nitrofurantoin were the most active drugs (98.1%, 95.8% and 95.2% susceptible strains, respectively) followed by ciprofloxacin, amoxicillin/clavulanic acid and cefuroxime (91.7%, 82.5% and 82.4%, respectively). Resistance to ciprofloxacin was >10% in Brazil, Spain, Italy and Russia. Overall, Proteus mirabilis were more susceptible to β-lactams and less susceptible to non-β-lactams than E. coli, whereas Klebsiella pneumoniae strains, which are intrinsically resistant to ampicillin, were less susceptible to mecillinam (88.8%), fosfomycin (87.9%), cefuroxime (78.6%) and nitrofurantoin (17.7%). Resistance was rare in Staphylococcus saprophyticus, with the exception of ampicillin (36.4%) and trimethoprim/sulfamethoxazole (10.2%). In Italy, Spain, Brazil and Russia, the countries most affected by antimicrobial resistance, extended-spectrum β-lactamase (ESBL) enzymes (mainly CTX-M type) were detected in 48 strains (39 E. coli, 6 K. pneumoniae and 3 P. mirabilis). Despite wide intercountry variability in bacterial susceptibility rates to the other antimicrobials tested, fosfomycin and mecillinam have preserved their in vitro activity in all countries investigated against the most common uropathogens.     

Blood and salivary concentrations of sulfamethoxazole and trimethoprim in man

Saliva/blood and saliva/plasma concentration ratios were determined for sulfamethoxazole and trimethoprim following oral administration of cotrimoxazole to healthy human subjects. The mean experimentally determined saliva/plasma concentration ratios for sulfamethoxazole and trimethoprim were 0.0157 and 1.13, respectively. These values were shown to be in reasonable agreement with theoretical predictions. It was demonstrated that partitioning of drugs from saliva into the buccal must be considered in making theoretical predictions.     

Pharmacokinetics of dapsone gel, 5% for the treatment of acne vulgaris

BACKGROUND: Oral dapsone has been available for over 60 years and has been used to treat severe acne vulgaris; however, the oral formulation is known to cause dose-dependent haematological reactions and is currently indicated only for diseases such as dermatitis herpetiformis and Hansen's disease. A gel formulation of dapsone was recently developed to treat acne vulgaris. As dapsone is administered topically, it was expected that systemic absorption would be considerably lower than that observed with oral dapsone therapy, thereby avoiding any adverse haematological effects. OBJECTIVE: To report the pharmacokinetic profile of topically applied dapsone gel, 5% in the treatment of acne vulgaris. STUDY PARTICIPANTS AND METHODS: Three prospective, open-label studies enrolled a total of 548 subjects with acne vulgaris: two phase I pharmacokinetic studies (crossover and drug interaction) and one phase III long-term safety study. In the crossover study (n = 18), topical dapsone gel applied twice daily for a total of 14 days to 22.5% of the body surface area was compared with a single dose of oral dapsone 100mg (the typical clinical dose). In the drug-interaction study (n = 24), oral trimethoprim/sulfamethoxazole monotherapy, topical dapsone gel monotherapy and the two in combination were used twice daily for 7, 21 and 7 days, respectively. In the long-term safety study (n = 506), topical dapsone gel was applied twice daily to acne-affected areas for up to 12 months. Blood samples were drawn at various timepoints in each study to assess drug and metabolite concentrations. Systemic concentrations of dapsone, N-acetyl dapsone, dapsone hydroxylamine, trimethoprim and sulfamethoxazole were determined, according to the study design. RESULTS: In the crossover study, the mean area under the plasma concentration-time curve (AUC) from 0 to 24 hours for dapsone was 417.5 ng x h/mL after 2 weeks of dapsone gel therapy (n = 10), compared with an AUC from time zero to infinity of 52,641 ng x h/mL after a single dose of oral dapsone; this represents a 126-fold lower systemic exposure for dapsone gel at typical therapeutic doses. In the drug-interaction study, the AUC from 0 to 12 hours for dapsone was 221.52 ng x h/mL after 3 weeks of dapsone gel monotherapy compared with 320.3 ng x h/mL after 1 week of coadministration with trimethoprim/sulfamethoxazole. In the long-term safety study, the mean plasma dapsone concentrations ranged from 7.5 to 11 ng/mL over 12 months. Overall, total systemic exposures to dapsone and its metabolites were approximately 100-fold less for dapsone gel than for oral dapsone, even in the presence of trimethoprim/sulfamethoxazole. There were no reports of any haematological adverse events. CONCLUSIONS: Topical application of dapsone gel in various settings ranging from 2 weeks to 12 months resulted in systemic exposures to dapsone and its metabolites that were approximately 100-fold less than those after oral dapsone at a therapeutic dose level. The concentrations of dapsone and its metabolites reached steady state and did not increase during prolonged treatment.     

Pharmacokinetics of cefradine, sulfamethoxazole and trimethoprim and their metabolites in a patient with peritonitis undergoing continuous ambulatory peritoneal dialysis

Cefradine and co-trimoxazole pharmacokinetics were studied in a patient with peritonitis that complicated continuous ambulatory peritoneal dialysis (CAPD). Concentrations in the plasma reached after oral administration of 500 mg cefradine four times daily and 400/80 mg co-trimoxazole four times daily were for cefradine 100g/ml, for trimethoprim 15g/ml, and for sulfamethoxazole 100/ml, respectively. In the dialysate concentrations were reached of 35–70/ml cefradine, 2–5/ml trimethoprim and 8–17g/ml sulfamethoxazole. The values for sulfamethoxazole are regarded too low to be clinically effective. Half-lives protein binding values and CAPD clearances are presented. Low CAPD clearances were obtained during the night and high values during the day. The dosage yielded too high plasma trimethoprim concentrations, while sulfamethoxazole dialysate concentrations were too low. It seems questionable therefore whether co-trimoxazole can be used orally for the treatment of CAPD peritonitis.     

Multiple-delayed release formulation approach for the treatment of methicillin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most frequent nosocomial pathogens in developed countries. Although several novel antibacterial agents possessing novel mode of action have been developed to date, the continuous effort to investigate an effective combination of front-line drugs is considered important in anti-MRSA drug development. The combination chemotherapy with front-line drugs is expected to provide effective, safe, and less expensive treatment. Oral trimethoprim/sulfamethoxazole combination therapy has been utilized for treatment of several nosocomical infections. Importantly, no antagonism has been reported for combinations of trimethoprim with many other front-line antibiotics. MiddleBrook Pharmaceuticals has developed the pulsatile delivery systems of three to four different antibacterial agents, including trimethoprim and sulfamethoxazole, for the treatment of MRSA infections. The liberation of individual drugs theoretically follows a programmable lag phase (no release) from the time of administration. Pulsatile drug delivery system provides optimal release profiles for a combination of drugs. The clinical data that would be obtained based on these claims are expected to be of significance in terms of developing combination chemotherapy for MRSA infections via a pulsatile drug release control system.     

20株阴沟肠杆菌耐药性及耐复方磺胺甲(口恶)唑相关基因研究

目的 探讨临床分离的阴沟肠杆菌耐药性和耐复方磺胺甲(口恶)唑(SMZ/TMP)相关基因存在状况.方法 采用ATB药敏试验板微量肉汤法测定临床分离的20株阴沟肠杆菌对20种抗菌药物的敏感性,采用PCR检测耐复方磺胺甲(口恶)唑相关基因sull、dfrA1和dfrA17.结果 20株菌对亚胺培南和美罗培南均敏感,对其他抗菌药物的不敏感率在25.0%～100%之间.sulⅠ、dfrA1和dfrA17基因阳性率为85.0%(17/20)、5.0%(1/21)、60.0%(12/20).结论 阴沟肠杆菌具明显的多重耐药特征.耐复方磺胺甲(口恶)唑相关基因携带率很高.     

A high performance liquid chromatography method for trimethoprim utilizing solid-phase column extraction

The antibiotic combination of sulfamethoxazole and trimethoprim was evaluated for treatment of peritonitis in patients in renal failure undergoing continuous ambulatory peritoneal dialysis. Although current methods of analysis were adequate for measurement of sulfamethoxazole, a review of the available methods of analysis for trimethoprim did not yield a satisfactory method. Therefore, a high performance liquid chromatography (HPLC) assay was developed to follow the pharmacokinetics of trimethoprim in serum and peritoneal dialysate fluid. In this assay, trimethoprim is extracted from plasma, serum, or dialysate fluid by solid-phase column chromatography that is efficient (82% recovery), quick, and simple to use. The HPLC method utilizes a common reverse-phase system with a 0.01 M sodium acetate and acetonitrile mobile phase and detection at 254 nm. The assay offers excellent between-run replication (p = 0.96), high sensitivity (0.05 microgram/mL), and linearity over a wide range (2-100 micrograms/ml; r = 0.99). The method offers freedom from interference by metabolites and a wide range of commonly administered drugs. It is suitable for other pharmacokinetic studies involving trimethoprim but not its metabolites, and also for clinical assay of trimethoprim in situations where high levels of the antibiotic are necessary to combat resistant organisms and in serious infections by opportunistic organisms such as Pneumocystis carinii.     

Effect of Streptococcus pneumoniae and Influenza A Virus on Middle Ear Antimicrobial Pharmacokinetics in Experimental Otitis Media

Antimicrobial treatment failures in children with acute otitis media and concomitant viral respiratory tract infection prompted us to study the effects of influenza A virus infection on middle ear antimicrobial drug penetration. Using a chinchilla model of Streptococcus pneumoniae we compared middle ear elimination rates in 4 groups of chinchillas: (1) control, (2) influenza A virus inoculation alone intranasally, (3) both influenza A and S. pneumoniae inoculation directly into the middle ear, and (4) S. pneumoniae inoculation alone into the middle ear. After infection was established, a solution containing amoxicillin, sulfamethoxazole, and trimethoprim was instilled into the middle ear and removed 4 hours later. The rate constant of elimination and half-life were calculated from measured drug concentrations initially and at 4 hours. S. pneumoniae infection alone significantly shortened the middle ear elimination half-life compared with the control group: amoxicillin, 2.65 ± 0.73 vs. 6.63 ± 2.55 hr; sulfamethoxazole, 1.75 ± 0.28 vs. 2.74 ± 0.6 hr; and trimethoprim, 1.06 ± 0.14 vs. 1.56 ± 0.34 hr (n = 16 ears, p values all <0.01). The combined influenza virus and S. pneumoniae infection significantly lengthened the half-life compared with the S. pneumoniae infection alone: amoxicillin, 5.65 ± 6.44 vs. 2.65 ± 0.73 hr; sulfamethoxazole, 2.5 ± 0.85 vs. 1.75 ± 0.28 hr; and trimethoprim, 1.26 ± 0.42 vs. 1.06 ± 0.14 hr (n = 16 ears, p values all <0.01). Influenza virus produced the longest half-lives for all 3 antimicrobials: amoxicillin 25.52 ± 14.96 hr; sulfamethoxazole, 5.46 ± 0.87 hr; and trimethoprim, 2.57 ± 0.75 hr. These effects demonstrate that influenza and S. pneumoniae infections alone and together affect middle ear antimicrobial penetration. The decreased penetration of antimicrobials that occurred with the combined viral and bacterial infection vs. the bacteria alone supports the clinical observation that patients with infections caused by both organisms may have decreased middle ear antimicrobial concentrations, producing treatment failures.     

Trimethoprim and sulfamethoxazole are selective inhibitors of CYP2C8 and CYP2C9, respectively.

To evaluate the inhibitory effects of trimethoprim and sulfamethoxazole on cytochrome P450 (P450) isoforms, selective marker reactions for CYP1A2, CYP2A6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1, and CYP3A4 were examined in human liver microsomes and recombinant CYP2C8 and CYP2C9. The in vivo drug interactions of trimethoprim and sulfamethoxazole were predicted in vitro using [I]/([I] + K(i)) values. With concentrations ranging from 5 to 100 microM, trimethoprim exhibited a selective inhibitory effect on CYP2C8-mediated paclitaxel 6alpha-hydroxylation in human liver microsomes and recombinant CYP2C8, with apparent IC(50) (K(i)) values of 54 microM (32 microM) and 75 microM, respectively. With concentrations ranging from 50 to 500 microM, sulfamethoxazole was a selective inhibitor of CYP2C9-mediated tolbutamide hydroxylation in human liver microsomes and recombinant CYP2C9, with apparent IC(50) (K(i)) values of 544 microM (271 microM) and 456 microM, respectively. With concentrations higher than 100 microM trimethoprim and 500 microM sulfamethoxazole, both drugs lost their selectivity for the P450 isoforms. Based on estimated total hepatic concentrations (or free plasma concentrations) of the drugs and the scaling model, one would expect in vivo in humans 80% (26%) and 13% (24%) inhibition of the metabolic clearance of CYP2C8 and CYP2C9 substrates by trimethoprim and sulfamethoxazole, respectively. In conclusion, trimethoprim and sulfamethoxazole can be used as selective inhibitors of CYP2C8 and CYP2C9 in in vitro studies. In humans, trimethoprim and sulfamethoxazole may inhibit the activities of CYP2C8 and CYP2C9, respectively.     

Simultaneous solubility and dissolution rate of sulfamethoxazole and trimethoprim in binary mixture

The solubilities of trimethoprim in solutions with different pH values decreased in the presence of sulfamethoxazole, while that of the latter increased in the presence of the first. The dissolution rate of trimethoprim in HCl (0.1 mol/1) was the same in the presence and absence of sulfamethoxazole. That of sulfamethoxazole however, decreased in the presence of trimethoprim. The different reasons were explained.     

RP-HPLC法测定小儿增效联磺颗粒剂中三组份含量

目的：建立RP-HPLC外标法测定小儿增效联磺颗粒剂中三种有效成分的含量。方法：采用C18色谱柱，检测波长230nm，流动相0.05mol/mL磷酸二氢钾-甲醇（75：25）。结果：平均回收率磺胺甲恶唑99.0%。磺胺嘧啶99.5%。甲氧苄啶98.8%。结论：方法简单，快速，灵敏，准确。     

Antimicrobial susceptibility of Escherichia coli from community-acquired urinary tract infections in Europe: the ECO·SENS study revisited

This study determined the antimicrobial susceptibility of Escherichia coli causing community-acquired, acute, uncomplicated, non-recurrent urinary tract infection in unselected women aged 18-65 years and compared the results with those obtained 8 years earlier in the first ECO·SENS study (1999-2000). During 2007-2008, urine samples were taken from 1697 women in Austria, Greece, Portugal, Sweden and the UK. The countries were chosen to represent areas of Europe indicated to have more (Greece and Portugal) or less (UK, Austria and Sweden) problems with resistance. Antimicrobial susceptibility testing of 903 E. coli isolates (150-200 isolates per country) to 14 antimicrobials was performed by disk diffusion using European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints. In E. coli, resistance to mecillinam, cefadroxil (representing oral cephalosporins), nitrofurantoin, fosfomycin trometamol, gentamicin and the third-generation cephalosporins cefotaxime and ceftazidime was <2%, with the following exceptions: gentamicin in Portugal (2.8%); fosfomycin in Greece (2.9%); and cephalosporins in Austria (2.7-4.1%). Resistance levels were higher for amoxicillin/clavulanic acid (2.0-8.9%) and ciprofloxacin (0.5-7.6%) and much higher to ampicillin (21.2-34.0%), sulfamethoxazole (21.2-31.3%), trimethoprim (14.9-19.1%) and trimethoprim/sulfamethoxazole (14.4-18.2%). Resistance to quinolones and trimethoprim increased between the ECO·SENS I (1999-2000) and ECO·SENS II (2007-2008): nalidixic acid 4.3% to 10.2%; ciprofloxacin 1.1% to 3.9%; and trimethoprim 13.3% to 16.7%. In the previous study, no isolates with extended-spectrum β-lactamase were found; however, in the present study 11 isolates were identified as having either CTX-M or AmpC.     

Can the Enhanced Renal Clearance of Antibiotics in Cystic Fibrosis Patients Be Explained by P-Glycoprotein Transport?

Purpose. To investigate in vitro if P-glycoprotein (P-gp) transport can differentiate between antibiotic drugs exhibiting increased active renal clearance (CL_r) in cystic fibrosis (CF) patients (i.e., dicloxacillin, trimethoprim) and drugs that do not exhibit this phenomenon (i.e., cefsulodin, sulfamethoxazole). Methods. Transport studies were carried out in MDCK (wild type) and MDR1-MDCK (P-gp overexpressing) cells that were grown to confluence on Transwell inserts. [¹⁴C]-mannitol transport and transepithelial electrical resistance (TEER) were measured to validate the integrity of the cells. Drug concentrations were analyzed using HPLC. Results. Dicloxacillin and trimethoprim are substrates of P-gp (BA/AB ratios in MDR1-MDCK cells are 32 and 50, respectively). P-gp inhibitors (i.e., GG918, cyclosporine, ketoconazole, vinblastine) decreased the BA transport of dicloxacillin and trimethoprim and increased the AB transport of trimethoprim while non-P-gp inhibitors (e.g., PAH) had no effect. In contrast, cefsulodin and sulfamethoxazole are not substrates of P-gp (BA/AB values in MDCK and MDR1-MDCK cells are 1). Conclusions. Our in vitro studies suggest that P-glycoprotein may play a role in increasing renal clearance of drug substrates in CF patients. Dicloxacillin and trimethoprim, which are both substrates of P-gp, show increased active renal clearance in CF patients while cefsulodin and sulfamethoxazole, which are not P-gp substrates, do not show increased active renal clearance in CF patients.     

毛细管区带电泳法测定复方磺胺甲噁唑片中两组分的含量

建立毛细管区带电泳法测定复方磺胺甲口恶唑片中磺胺甲口恶唑和甲氧苄啶含量的方法。用 2 5mmol/L硼砂缓冲液分离 ,以氯霉素为内标 ,2 14nm为测定波长。结果 :样品中二组分完全分离且呈良好线性关系 ,加样回收率分别为 10 1.0 % ( RSD =1.4 3% ) ,10 0 .3% ( RSD =1.2 8% )。     

高效毛细管电泳法测定复方磺胺甲噁唑片中磺胺甲噁唑和甲氧苄啶的含量

目的　测定复方磺胺甲 口 恶 唑片中磺胺甲 口 恶 唑及甲氧苄啶的含量。方法　采用高效毛细管电泳法 ,肉桂酸为内标 ,运行缓冲液为 2 5mmol·L-1硼砂 硼酸缓冲液 (pH9.2 ) ,内含 3 0mmol·L-1十二烷基磺酸钠及 10 %乙腈 ;运行电压 2 0kV ;检测波长2 14nm。结果　磺胺甲口 恶 唑和甲氧苄啶线性范围分别为 5 0～ 2 5 0 μg/mL(r =0 .9997)和 10～ 5 0 μg/mL(r =0 .9986) ,平均回收率分别为 99.0 %和 98.6% ,RSD分别为 2 .0 %及 2 .6% (n =6)。结论　该方法简便、准确、灵敏 ,适用于复方磺胺甲 口 恶 唑片的质量控制     

Simultaneous determination and validation of antimicrobials in plasma and tissue of actinomycetoma by high-performance liquid chromatography with diode array and fluorescence detection

A simple, precise, and reliable chromatographic method was developed for the simultaneous determination in plasma and infected tissue of five antimicrobials proposed for the treatment of actinomycotic mycetoma: amoxicillin, trimethoprim, linezolid, sulfamethoxazole and garenoxacin. Separation of the analytes was achieved on an Atlantis dC18 column (150 mm × 4.6 mm, ID 5 μm) with a mobile phase composed of acetonitrile and trifluoroacetic acid (ATF) 0.1% (v/v) using a gradient program. The detection was carried out using a diode array detector at 254 nm and in a fluorescence detector at wavelengths of excitation and emission of 292 nm and 392 nm for linezolid and sulfamethoxazole, and 292 nm and 408 nm for garenoxacin, respectively. The intraday precision was in the range of 0.7–15% of relative standard deviations (%R.S.D.) for plasma and 1–18% for tissue. Linearity range was from 2.4 to 20 μg/ml for amoxicillin, 0.3 to 20 μg/ml for trimethoprim, sulfamethoxazole and linezolid, and 0.3 to 10 μg/ml for garenoxacin. Acetonitrile was used to precipitate proteins from plasma. Recoveries in plasma ranged from 71% to 118% and in infected tissue from 78% to 122%. Limits of detection (LODs) were 1.2 and 0.5 μg/ml for amoxicillin in plasma and tissue, respectively and 0.15 and 1.2 μg/ml in plasma and tissue, respectively for the other antimicrobials. The method can be applied for individual or simultaneous determination of the antimicrobials in plasma and tissue of mouse infected with actinomycetoma.