Monitoring of co-trimoxazole concentrations in serum during treatment of pneumocystis carinii pneumonia

Observational study of the clinical utility of sulfamethoxazole serum level monitoring in the treatment of brain abscesses due to Nocardia species

Although there is a lack of data in trimethoprim-sulfamethoxazole (TMP-SMX) serum monitoring utility for invasive nocardial infections, therapeutic drug monitoring is widely used to optimize dosing and avoid adverse reactions that may cause treatment interruption.We retrospectively reviewed all adults who received TMP-SMX to treat nocardial brain abscess and had SMX serum level testing from 2010 to 2020.Twenty-two patients received treatment with TMP-SMX for Nocardia species brain abscess and 16 (72.7%) had a reported SMX level, with a median patient age of 65.5 years (interquartile range, IQR 59.5-72.5). Compared to those who did not have a documented SMX serum level, patients with SMX levels had a shorter median course of TMP-SMX treatment (322 days [IQR 188-365] vs. 365 [IQR 224-365]; P = .31) and higher therapeutic induction dose (10 [62.5%] vs. 3 [50%]; P = .92). Similarly, they were more frequently on hemodialysis (3 [13.6%] vs. 1 [4.5%]; P = > .99). The median peak level was 158.5 (IQR 120-218) μg/mL, collected at 2 hours (75%) post-administration in the induction phase (81.3%). Patients with documented SMX levels had fewer reported drug toxicity (5 [31.3%] vs. 4 [66.7%]; P = .1) than those without SMX levels. Among the five patients who reported TMP-SMX-related toxicity, 4 (80%) had an SMX peak level >150 μg/mL. There was no difference in the cure, relapse, and death rates among the two groups.While SMX level was not associated with Nocardia species brain abscess cure rates and mortality, most patients with SMX peak >150 μg/mL experienced drug toxicity.

External Evaluation of Two Pediatric Population Pharmacokinetics Models of Oral Trimethoprim and Sulfamethoxazole

The antibiotic combination trimethoprim (TMP)-sulfamethoxazole (SMX) has a broad spectrum of activity and is used for the treatment of numerous infections, but pediatric pharmacokinetic (PK) data are limited. We previously published population PK (popPK) models of oral TMP-SMX in pediatric patients based on sparse opportunistically collected data (POPS study) (J. Autmizguine, C. Melloni, C. P. Hornik, S. Dallefeld, et al., Antimicrob Agents Chemother 62:e01813-17, 2017, https://doi.org/10.1128/AAC.01813-17). We performed a separate PK study of oral TMP-SMX in infants and children with more-traditional PK sample collection and independently developed new popPK models of TMP-SMX using this external data set. The POPS data set and the external data set were each used to evaluate both popPK models. The external TMP model had a model and error structure identical to those of the POPS TMP model, with typical values for PK parameters within 20%. The external SMX model did not identify the covariates in the POPS SMX model as significant. The external popPK models predicted higher exposures to TMP (median overprediction of 0.13 mg/liter for the POPS data set and 0.061 mg/liter for the external data set) and SMX (median overprediction of 1.7 mg/liter and 0.90 mg/liter) than the POPS TMP (median underprediction of 0.016 mg/liter and 0.39 mg/liter) and SMX (median underprediction of 1.2 mg/liter and 14 mg/liter) models. Nonetheless, both models supported TMP-SMX dose increases in infants and young children for resistant pathogens with a MIC of 1 mg/liter, although the required dose increase based on the external model was lower. (The POPS and external studies have been registered at ClinicalTrials.gov under registration no. NCT01431326 and NCT02475876, respectively.).

Too Much of a Good Thing: Defining Antimicrobial Therapeutic Targets to Minimize Toxicity

Antimicrobials are a common cause of drug toxicity. Understanding the relationship between systemic antimicrobial exposure and toxicity is necessary to enable providers to take a proactive approach to prevent undesired drug effects. When an exposure threshold has been defined that predicts drug toxicity, therapeutic drug monitoring (TDM) can be performed to assure drug exposure does not exceed the defined threshold. Although some antimicrobials have well-defined dose-dependent toxicities, many other exposure-toxicity relationships have either not been well-defined or, in some cases, not been evaluated at all. In this review, we examine the relationship between exposures and toxicities for antibiotic, antifungal, and antiviral agents. Furthermore, we classify these relationships into four categories: known association between drug exposure and toxicity such that clinical implementation of a specific exposure threshold associated with toxicity for TDM is supported (category 1), known association between drug exposure and toxicity but the specific exposure threshold associated with toxicity is undefined (category 2), association between drug exposure and toxicity has been suggested but relationship is poorly defined (category 3), and no known association between drug exposure and toxicity (category 4). Further work to define exposure-toxicity thresholds and integrate effective TDM strategies has the potential to minimize many of the observed antimicrobial toxicities.

LC-MS/MS method for nine different antibiotics

BACKGROUND AND AIMS

TDM of antibiotics can bring benefits to patients and healthcare systems by providing better treatment and saving healthcare resources. We aimed to develop a multi-analyte method for several diverse antibiotics using LC-MS/MS.

MATERIALS AND METHODS

Sample preparation consisted of protein precipitation with methanol, dilution and online extraction using a Turboflow Cyclone column. Separation was performed on a Synergi 4 µm Max RP column and deuterated forms of three antibiotics were used as internal standards.

RESULTS

We present a LC-MS/MS method for the quantitative determination of nine antibiotics, including five cephalosporins, the carbapenem ertapenem, the fluoroquinolone ciprofloxacin as well as the combination drug trimethoprim-sulfamethoxazole from plasma. Additionally, unbound ertapenem and cefazolin were analyzed in plasma water after ultrafiltration using plasma calibrators. Results from routine TDM show the applicability of the method.

CONCLUSION

The presented method is precise and accurate and was introduced in a university hospital, permitting fast TDM of all nine analytes. It was also used in a clinical study for measuring cefazolin free and total concentrations.

Population Pharmacokinetics of Trimethoprim-Sulfamethoxazole in Infants and Children

Trimethoprim (TMP)-sulfamethoxazole (SMX) is used to treat various types of infections, including community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) and Pneumocystis jirovecii infections in children. Pharmacokinetic (PK) data for infants and children are limited, and the optimal dosing is not known. We performed a multicenter, prospective PK study of TMP-SMX in infants and children. Separate population PK models were developed for TMP and SMX administered by the enteral route using nonlinear mixed-effects modeling. Optimal dosing was determined on the basis of the matching adult TMP exposure and attainment of the surrogate pharmacodynamic (PD) target for efficacy, a free TMP concentration above the MIC over 50% of the dosing interval. Data for a total of 153 subjects (240 samples for PK analysis) with a median postnatal age of 8 years (range, 0.1 to 20 years) contributed to the analysis for both drugs. A one-compartment model with first-order absorption and elimination characterized the TMP and SMX PK data well. Weight was included in the base model for clearance (CL/F) and volume of distribution (V/F). Both TMP and SMX CL/F increased with age. In addition, TMP and SMX CL/F were inversely related to the serum creatinine and albumin concentrations, respectively. The exposure achieved in children after oral administration of TMP-SMX at 8/40 mg/kg of body weight/day divided into administration every 12 h matched the exposure achieved in adults after administration of TMP-SMX at 320/1,600 mg/day divided into administration every 12 h and achieved the PD target for bacteria with an MIC of 0.5 mg/liter in >90% of infants and children. The exposure achieved in children after oral administration of TMP-SMX at 12/60 and 15/75 mg/kg/day divided into administration every 12 h matched the exposure achieved in adults after administration of TMP-SMX at 640/3,200 mg/day divided into administration every 12 h in subjects 6 to <21 years and 0 to <6 years of age, respectively, and was optimal for bacteria with an MIC of up to 1 mg/liter.

Relationship of Sulfamethoxazole Therapeutic Drug Monitoring to Clinical Efficacy and Toxicity: A Retrospective Cohort Study

BACKGROUND

Trimethoprim/sulfamethoxazole (TMP/SMX) is the treatment of choice for infections caused by Pneumocystis jiroveci, Stenotrophomonas maltophilia, and Nocardia species, but the utility of therapeutic drug monitoring (TDM) is unclear. The objective of this study was to evaluate the association between peak sulfamethoxazole (SMX) serum levels and clinical outcomes to determine the utility of TDM of TMP/SMX.

METHODS

This study was conducted in patients receiving treatment with TMP/SMX for culture-positive infection who underwent TDM from 2003 to 2013. Peak SMX levels were classified as below target (<100 mcg/mL), within target (100-150 mcg/mL), or above target (>150 mcg/mL). The effect of initial SMX levels on clinical outcomes was compared using propensity score adjusted multivariable Cox models.

RESULTS

A total of 279 patients had SMX monitoring performed. The primary infecting organisms were P. jiroveci (47%) and S. maltophilia (38%). A majority of patients (74%) had an SMX peak level outside of the target range. Using direct regression propensity score adjustment, there was no significant difference between rates of clinical failure and initial peak SMX level (<100 mcg/mL versus 100-150 mcg/mL: hazard ratio 0.92, 95% confidence interval, 0.28-3.07 and >150 mcg/mL versus 100-150 mcg/mL: hazard ratio 1.92, 95% confidence interval, 0.72-5.09). Similarly, there was no relationship between SMX level and toxicity (P = 0.42).

CONCLUSIONS

Sulfamethoxazole serum levels outside the target range were not associated with increased rates of clinical failure in patients treated with TMP/SMX. There was also no association found between peak SMX levels and rates of adverse events. Although this study cannot disprove that dose adjustments after the initial SMX peak level may have affected clinical outcomes, the results suggest that the utility of SMX TDM may be limited to a subset of patients and requires further prospective investigation.

Suboptimal cotrimoxazole prophylactic concentrations in HIV-infected children according to the WHO guidelines

AIMS

A clinical study was conduct in HIV-infected children to evaluate the prophylactic doses of cotrimoxazole [sulfamethoxazole (SMX) and trimethoprim (TMP)] advised by the WHO.

METHODS

Children received lopinavir-based antiretroviral therapy with cotrimoxazole prophylaxis (200 mg of SMX/40 mg of TMP once daily). A nonlinear mixed effects modelling approach was used to analyse plasma concentrations. Factors that could impact the pharmacokinetic profile were investigated. The model was subsequently used to simulate individual exposure and evaluate different administration schemes.

RESULTS

The cohort comprised 136 children [average age: 1.9 years (range: [0.7-4]), average weight: 9.5 kg (range: [6-16.3])]. A dose per kg was justified by the significant influence of implementing an allometrically scaled body size covariate on SMX and TMP pharmacokinetics. SMX and TPM clearance were estimated at 0.49 l h^-1 /9.5 kg and 3.06 l h^-1 /9.5 kg, respectively. The simulated exposures obtained after administration of oral dosing recommended by the WHO for children from 10 to 15 kg were significantly lower than in adults for SMX and TMP. This could induce a reduction of effectiveness of cotrimoxazole. Simulations show that regimens of 30 mg kg^-1 of SMX and 6 mg kg^-1 of TMP in the 5-10 kg group and 25 mg kg^-1 of SMX and 5 mg kg^-1 of TMP in the 10-15 kg group are more suitable doses.

CONCLUSIONS

In this context of high prevalence of opportunistic infections, a lower exposure to cotrimoxazole in children than adults was noted. To achieve comparable exposure to adults, a dosing scheme per kg was proposed.

Treatment of Pneumocystis jirovecii pneumonia in HIV-infected patients: a review

INTRODUCTION

Pneumocystis pneumonia is a potentially life-threatening pulmonary infection that occurs in immunocompromised individuals and HIV-infected patients with a low CD4 cell count. Trimethoprim-sulfamethoxazole has been used as the first-line agent for treatment, but mutations within dihydropteroate synthase gene render potential resistance to sulfamide. Despite advances of combination antiretroviral therapy (cART), Pneumocystis pneumonia continues to occur in HIV-infected patients with late presentation for cART or virological and immunological failure after receiving cART. Areas covered: This review summarizes the diagnosis and first-line and alternative treatment and prophylaxis for Pneumocystis pneumonia in HIV-infected patients. Articles for this review were identified through searching PubMed. Search terms included: 'Pneumocystis pneumonia', 'Pneumocystis jirovecii pneumonia', 'Pneumocystis carinii pneumonia', 'trimethoprim-sulfamethoxazole', 'primaquine', 'trimetrexate', 'dapsone', 'pentamidine', 'atovaquone', 'echinocandins', 'human immunodeficiency virus infection', 'acquired immunodeficiency syndrome', 'resistance to sulfamide' and combinations of these terms. We limited the search to English language papers that were published between 1981 and March 2017. We screened all identified articles and cross-referenced studies from retrieved articles. Expert commentary: Trimethoprim-sulfamethoxazole will continue to be the first-line agent for Pneumocystis pneumonia given its cost, availability of both oral and parenteral formulations, and effectiveness or efficacy in both treatment and prophylaxis. Whether resistance due to mutations within dihydropteroate synthase gene compromises treatment effectiveness remains controversial. Continued search for effective alternatives with better safety profiles for Pneumocystis pneumonia is warranted.

Serum peak sulfamethoxazole concentrations demonstrate difficulty in achieving a target range: a retrospective cohort study

OBJECTIVES

Trimethoprim (TMP)/sulfamethoxazole (SMX) has consistently demonstrated great interindividual variability. Therapeutic drug monitoring may be used to optimize dosing. Optimal peak SMX concentration has been proposed as 100 to 150 μg/mL. The objective of our work was to determine the success rate of a TMP/SMX dosing guideline in achieving a targeted serum peak SMX concentration range.

METHODS

Our retrospective cohort study enrolled 305 adult hospitalized patients who received treatment with TMP/SMX and underwent serum peak SMX concentration monitoring from January 2003 to November 2011. Patients receiving low-dose TMP/SMX therapy (TMP <15 mg/kg/d) were compared with those receiving high-dose therapy (TMP >15 mg/kg/d).

RESULTS

Patients were classified into peak and modified peak SMX concentration cohorts based on time between TMP/SMX dose and SMX quantification. The association between dosing group and the outcome of the SMX level within the goal range was measured using logistic regression models. The primary outcome measured was serum peak SMX concentration 100 to 150 μg/mL. Serum peak SMX concentrations were attained within range for the peak and modified peak cohort 29% and 26% of the time, respectively. The median peak SMX concentration was 144 μg/mL (range 25-471 μg/mL). The low daily dose cohort demonstrated a trend toward improvement in the odds of target peak concentration range attainment. The results were similar regardless of the method used to adjust for baseline characteristics. The pure peak and modified peak cohorts had 44% and 46% of patients with above-target SMX peak concentrations, respectively.

CONCLUSIONS

Attainment of the intended target concentration range was low with no difference in attainment between the low-dose and high-dose cohorts. Higher proportions of patients had an above-target SMX peak, which may indicate that the dosing algorithm is overly aggressive in obtaining the therapeutic goal.

Serum concentration of co-trimoxazole during a high-dosage regimen

OBJECTIVES

Sulfamethoxazole and trimethoprim have been used for decades, yet high dosages are rarely reported. We aimed to measure blood concentrations of both molecules in this situation.

METHODS

Between 2002 and 2010, 22 patients received two tablets of co-trimoxazole three times a day, equivalent to a daily dosage of 2400 mg of sulfamethoxazole and 480 mg of trimethoprim. The trimethoprim and sulfamethoxazole concentrations were determined 3 h after administration using ion-paired HPLC.

RESULTS

In the presence of a negative control, which yielded no peaks at the retention times for trimethoprim and sulfamethoxazole, the mean ± SD value for sulfamethoxazole concentration was 161.01 ± 69.154 mg/L and the mean ± SD value for trimethoprim was 5.788 ± 2.74 mg/L.

CONCLUSIONS

These concentrations are largely above the trimethoprim and sulfamethoxazole MIC distributions as well as the trimethoprim resistance clinical breakpoint (4 mg/L) reported by EUCAST in 2012 for most bacterial pathogens, including Gram-positive species such as Staphylococcus aureus. Our results support proposing a high-dosage regimen of co-trimoxazole as a suitable alternative for methicillin-resistant S. aureus infections.

Tetrahydrobiopterin biosynthesis as an off-target of sulfa drugs

The introduction of sulfa drugs for the chemotherapy of bacterial infections in 1935 revolutionized medicine. Although their mechanism of action is understood, the molecular bases for most of their side effects remain obscure. Here, we report that sulfamethoxazole and other sulfa drugs interfere with tetrahydrobiopterin biosynthesis through inhibition of sepiapterin reductase. Crystal structures of sepiapterin reductase with bound sulfa drugs reveal how structurally diverse sulfa drugs achieve specific inhibition of the enzyme. The effect of sulfa drugs on tetrahydrobiopterin-dependent neurotransmitter biosynthesis in cell-based assays provides a rationale for some of their central nervous system-related side effects, particularly in high-dose sulfamethoxazole therapy of Pneumocystis pneumonia. Our findings reveal an unexpected aspect of the pharmacology of sulfa drugs and might translate into their improved medical use.

Safety and efficacy of co-trimoxazole for treatment and prevention of Plasmodium falciparum malaria: a systematic review

INTRODUCTION

Cotrimoxazole (CTX) has been used for half a century. It is inexpensive hence the reason for its almost universal availability and wide clinical spectrum of use. In the last decade, CTX was used for prophylaxis of opportunistic infections in HIV infected people. It also had an impact on the malaria risk in this specific group.

OBJECTIVE

We performed a systematic review to explore the efficacy and safety of CTX used for P.falciparum malaria treatment and prophylaxis.

RESULT

CTX is safe and efficacious against malaria. Up to 75% of the safety concerns relate to skin reactions and this increases in HIV/AIDs patients. In different study areas, in HIV negative individuals, CTX used as malaria treatment cleared 56%-97% of the malaria infections, reduced fever and improved anaemia. CTX prophylaxis reduces the incidence of clinical malaria in HIV-1 infected individuals from 46%-97%. In HIV negative non pregnant participants, CTX prophylaxis had 39.5%-99.5% protective efficacy against clinical malaria. The lowest figures were observed in zones of high sulfadoxine-pyrimethamine resistance. There were no data reported on CTX prophylaxis in HIV negative pregnant women.

CONCLUSION

CTX is safe and still efficacious for the treatment of P.falciparum malaria in non-pregnant adults and children irrespective of HIV status and antifolate resistance profiles. There is need to explore its effect in pregnant women, irrespective of HIV status. CTX prophylaxis in HIV infected individuals protects against malaria and CTX may have a role for malaria prophylaxis in specific HIV negative target groups.

Update on the diagnosis and treatment of Pneumocystis pneumonia

Pneumocystis is an opportunistic fungal pathogen that causes an often-lethal pneumonia in immunocompromised hosts. Although the organism was discovered in the early 1900s, the first cases of Pneumocystis pneumonia in humans were initially recognized in Central Europe after the Second World War in premature and malnourished infants. This unusual lung infection was known as plasma cellular interstitial pneumonitis of the newborn, and was characterized by severe respiratory distress and cyanosis with little or no fever and no pathognomic physical signs. At that time, only anecdotal cases were reported in adults and usually these patients had a baseline malignancy that led to a malnourished state. In the 1960-1970s additional cases were described in adults and children with hematological malignancies, but Pneumocystis pneumonia was still considered a rare disease. However, in the 1980s, with the onset of the HIV epidemic, Pneumocystis prevalence increased dramatically and became widely recognized as an opportunistic infection that caused potentially life-treating pneumonia in patients with impaired immunity. During this time period, prophylaxis against this organism was more generally instituted in high-risk patients. In the 1990s, with widespread use of prophylaxis and the initiation of highly active antiretroviral therapy (HAART) in the treatment of HIV-infected patients, the number of cases in this specific population decreased. However, Pneumocystis pneumonia still remains an important cause of severe pneumonia in patients with HIV infection and is still considered a principal AIDS-defining illness. Despite the decreased number of cases among HIV-infected patients over the past decade, Pneumocystis pneumonia continues to be a serious problem in immunodeficient patients with other immunosuppressive conditions. This is mostly due to increased use of immunosuppressive medications to treat patients with autoimmune diseases, following bone marrow and solid organ transplantation, and in patients with hematological and solid malignancies. Patients with hematologic disorders and solid organ and hematopoietic stem cell transplantation are currently the most vulnerable groups at risk for developing this infection. However, any patient with an impaired immunity, such as those receiving moderate doses of oral steroids for greater than 4 weeks or those receiving other immunosuppressive medications are at also at significant risk.

Anti-fungal Activity of Sulfamethoxazole toward Aspergillus Species

Invasive mycosis has significantly increased in frequency among immunocompromised hosts leading to excessive morbidity and mortality. The combination of sulfamethoxazole (SMX) and trimethoprim (TMP) has been used extensively for the treatment and prophylaxis of infections by various microbes. The purpose of this study is to estimate the anti-fungal activity of SMX-TMP and examine the mechanism of activity. To investigate the antimicrobial activity of SMX-TMP in vitro, a mixture of SMX and TMP at 5:1 was serially diluted and added to potato dextrose agar medium or C-limiting agar medium. Aspergillus species were inoculated on the medium plate with SMX-TMP. The growth of A. fumigatus and A. oryzae was inhibited by addition of SMX-TMP. The anti-Aspergillus effect depended on not TMP but SMX and that was inhibited by p-aminobenzoic acid (PABA). A. niger was not sensitive against SMX-TMP in PDA medium, but sensitive in C-limiting medium. Those results showed that the activity depends on culture medium. Furthermore, addition of human serum did not influence the activity of SMX. The finding in this study suggested that SMX might be effective against Aspergillus species in clinical practice and prophylaxis treatment.

N ‐glycosylation‐dependent block is a novel mechanism for drug‐induced cardiac arrhythmia

Voltage-gated potassium channels formed with the cardiac subunit HERG and a polymorphic variant of MinK-related peptide 1 (MiRP1) exhibit increased susceptibility to the antibiotic sulfamethoxazole (SMX) compared with channels formed with wild-type (WT) subunits. Here the molecular bases for SMX high-affinity block are investigated. The polymorphism causes a benign T to A amino acid mutation at position 8 (T8A) that destroys an N-glycosylation site of MiRP1. In vitro disruption of glycosylation by mutagenesis or in vivo by treatment with neuraminidase is associated with increased susceptibility to SMX and to other elementary agents such as divalent cations. Defective glycosylation does not affect the ability of T8A to form stable complexes with HERG, but rather it increases drug susceptibility through structural modifications in the channel complex. We conclude that N-glycosylation may play a key role in the etiology of life-threatening arrhythmia.

In vitro activities of pentamidine, pyrimethamine, trimethoprim, and sulfonamides against Aspergillus species

The susceptibilities of 70 strains of Aspergillus species were tested against seven different sulfa drugs and pentamidine by a microdilution method with RPMI 1640 and yeast nitrogen base media. Sulfamethoxazole, sulfadiazine, and pentamidine were active in vitro. The MICs obtained with RPMI 1640 were significantly higher than those with yeast nitrogen base. More studies are needed to further elucidate the action of these drugs.

A common polymorphism associated with antibiotic-induced cardiac arrhythmia

Drug-induced long QT syndrome (LQTS) is a prevalent disorder of uncertain etiology that predisposes to sudden death. KCNE2 encodes MinK-related peptide 1 (MiRP1), a subunit of the cardiac potassium channel I(Kr) that has been associated previously with inherited LQTS. Here, we examine KCNE2 in 98 patients with drug-induced LQTS, identifying three individuals with sporadic mutations and a patient with sulfamethoxazole-associated LQTS who carried a single-nucleotide polymorphism (SNP) found in approximately 1.6% of the general population. While mutant channels showed diminished potassium flux at baseline and wild-type drug sensitivity, channels with the SNP were normal at baseline but inhibited by sulfamethoxazole at therapeutic levels that did not affect wild-type channels. We conclude that allelic variants of MiRP1 contribute to a significant fraction of cases of drug-induced LQTS through multiple mechanisms and that common sequence variations that increase the risk of life-threatening drug reactions can be clinically silent before drug exposure.

Drug monitoring during the treatment of AIDS-associated Pneumocystis carinii pneumonia with trimethoprim-sulfamethoxazole

OBJECTIVE

To monitor trimethoprim and sulfamethoxazole plasma levels in patients with AIDS-associated Pneumocystis carinii pneumonia.

METHOD

Trimethoprim-sulfamethoxazole steady-state plasma concentrations were measured by high-pressure liquid chromatography during 37 episodes of Pneumocystis carinii pneumonia in patients with AIDS. Initially, 15-23 mg/kg/day trimethoprim and 75-115 mg/kg/day sulfamethoxazole were given i.v. Assuming a therapeutic range for trimethoprim from 4 to 10 microg/ml, the doses were adjusted if trimethoprim levels were found to be outside this range.

RESULTS

Mean concentrations were 6.7+/-3.3 g/ml for trimethoprim and 187+/-56 microg/ml for sulfamethoxazole. A widespread inter-patient range was found and could be decreased after dose adjustment. Enzyme inducing co-medication did not influence plasma concentrations. In patients with coexisting chronic liver disease, significantly increased sulfamethoxazole plasma levels were observed. A correlation could be demonstrated between serum creatinine and trimethoprim plasma levels. Adverse reactions associated with co-trimoxazole occurred during 65% of treatment periods and increased with increasing trimethoprim-sulfamethoxazole levels, as well as increasing length of treatment. Therapy only had to be prematurely discontinued in one patient. Overall mortality was 2.7%

CONCLUSION

Monitoring of co-trimoxazole levels during the treatment of P. carinii pneumonia in AIDS may help in reducing the high variability of plasma-concentrations and in avoiding severe side-effects especially associated in patients with chronic liver disease or renal failure.

Pneumonia in AIDS patients in the critical care unit

Despite advances in prophylaxis and the reduction of mortality and morbidity resulting from highly active antiretroviral therapy, neumocystis pneumonia remains a common problem in HIV-infected patients. There are many possible causes for the continued prevalence of this condition. This article examines the characteristics, and some of the complex causes of P. carinii pneumonia in AIDS patients.