Determining the mechanisms underlying augmented renal drug clearance in the critically ill: use of exogenous marker compounds

Introduction

The aim of this study was to explore changes in glomerular filtration (GFR) and renal tubular function in critically ill patients at risk of augmented renal clearance (ARC), using exogenous marker compounds.

Methods

This prospective, observational pharmacokinetic (PK) study was performed in a university-affiliated, tertiary-level, adult intensive care unit (ICU). Patients aged less than or equal to 60 years, manifesting a systemic inflammatory response, with an expected ICU length of stay more than 24 hours, no evidence of acute renal impairment (plasma creatinine concentration <120 μmol/L) and no history of chronic kidney disease or renal replacement therapy were eligible for inclusion. The following study markers were administered concurrently: sinistrin 2,500 mg (Inutest; Laevosan, Linz, Austria), p-aminohippuric acid (PAH) 440 mg (4% p-aminohippuric acid sodium salt; CFM Oskar Tropitzsch, Marktredwitz, Germany), rac-pindolol 5 or 15 mg (Barbloc; Alphapharm, Millers Point, NSW, Australia) and fluconazole 100 mg (Diflucan; Pfizer Australia Pty Ltd, West Ryde, NSW, Australia). Plasma concentrations were then measured at 5, 10, 15, 30, 60 and 120 minutes and 4, 6, 12 and 24 hours post-administration. Non-compartmental PK analysis was used to quantify GFR, tubular secretion and tubular reabsorption.

Results

Twenty patients were included in the study. Marker administration was well tolerated, with no adverse events reported. Sinistrin clearance as a marker of GFR was significantly elevated (mean, 180 (95% confidence interval (CI), 141 to 219) ml/min) and correlated well with creatinine clearance (r =0.70, P <0.01). Net tubular secretion of PAH, a marker of tubular anion secretion, was also elevated (mean, 428 (95% CI, 306 to 550) ml/min), as was net tubular reabsorption of fluconazole (mean, 135 (95% CI, 100 to 169) ml/min). Net tubular secretion of (S)- and (R)-pinodolol, a marker of tubular cation secretion, was impaired.

Conclusions

In critically ill patients at risk of ARC, significant alterations in glomerular filtration, renal tubular secretion and tubular reabsorption are apparent. This has implications for accurate dosing of renally eliminated drugs.     

An audit of antiretroviral treatment use in HIV-infected patients in a London clinic: the limitations of observational databases when auditing antiretroviral treatment use

Objective

To audit the use of antiretroviral (ARV) treatment in a large treatment clinic in the UK against the British HIV Association (BHIVA) ARV treatment guidelines.

Methods

All patients under follow‐up between 1st January 2000 and 1st January 2001 were included. The most recent CD4 count and HIV RNA level prior to 1st January 2001, and the nadir CD4 count and peak HIV RNA level over follow‐up, were used to identify which patients should be receiving HAART according to the guidelines.

Results

One thousand two hundred and sixty‐four patients were included in the analysis (63.8% homosexual, 29.0% heterosexual risk; 72.9% white; 79.2% male). Almost half of patients had ever had a CD4 count below 200 cells/µL and over 80% had previously had a viral load above 4 log₁₀ HIV‐1 RNA copies/mL. Under 2000 BHIVA guidelines, treatment would be recommended in 77.4% patients. Overall, 819 patients were receiving ARV therapy. Two hundred and eighty‐five patients were not receiving treatment when guidelines suggest they should (including 33 patients who were receiving regimens not recommended in the guidelines). These patients were younger, less likely to be homosexual and had higher CD4 nadirs than those who were receiving ARV treatment. Almost half of these patients had previously received ARV therapy but were not currently receiving it.

Conclusion

Only a small proportion of patients at our centre were not receiving ARV treatment in line with national guidelines. While genuine reasons may exist for these departures from optimal care, this may simply reflect the limitations of using observational databases when auditing treatment use in a clinic setting.

     

Evidence for a national problem: continued rise in tuberculosis case numbers in urban areas outside London

WHO standards for tuberculosis (TB) control require monitoring and evaluation of TB control programmes. In London, TB rates have stabilised at 44 per 100,000 since 2005. In 38 urban areas outside London with TB rates above the national average, these continued to rise after 2004, to 28 per 100,000 in 2008 (15% increase). London has the highest proportion of TB cases in certain risk groups, but these are increasing rapidly outside London. Many TB control efforts focus on the capital, but with rates rising elsewhere in the country, this strategy is likely to fail in the long term.     

Malignant astrocytoma of the cervico-medullary junction masquerading as Guillain-Barr�� syndrome.

Brainstem gliomas are rare primary brain tumours which most commonly occur in the midbrain and pons. Malignant gliomas and tumours at the cervico-medullary junction are particularly unusual. The diagnosis of tumours at this site is particularly difficult using computed tomographic (CT) scanning owing to artifacts around the base of the skull. Intrinsic tumours of the cervico-medullary junction may lead to a dissociated motor deficit and the onset of symptoms can be rapid. We describe a patient in whom an isolated ascending motor deficit in association with a raised cerebrospinal fluid protein and a normal CT scan led to an erroneous diagnosis of Guillain-Barré syndrome. The patient was treated on the intensive care unit for an 8-week period before further investigation demonstrated a malignant glioma of the cervico-medullary junction. We recommend confirmation of the diagnosis of polyradiculopathy by nerve conduction studies wherever possible.     

Evaluation of a children's temper-taming program.

OBJECTIVE: To examine the effectiveness of a group cognitive-behavioural therapy program in reducing anger and aggressive behaviour in children. METHOD: Study participants were 68 children aged 7 to 13 years and their parents. A total of 12 groups were run at an outpatient children's mental health centre. The children were referred to the groups by their clinician for assistance in reducing their aggressive behaviour. We obtained quantitative information on the effectiveness of the group from the children and their parents, who completed questionnaires before the first session and after the last session. The children completed the Children's Inventory of Anger (CIA), and the parents completed the Children's Hostility Inventory (CHI). We used t tests and analyses of covariance to test for posttreatment differences. RESULTS: Results were available for 56 children. At posttreatment, children reported that the intensity of their anger had decreased (CIA, t41 = 4.39, P < 0.0001), and parents indicated a reduction in the frequency of aggression (CHI-Aggression, t44 = 2.82, P < 0.01) and hostility (CHI-Hostility, t44 = 4.93, P < 0.0001) in their children. CONCLUSIONS: The group program appeared to reduce children's anger and aggression. However, the results are preliminary, and further controlled evaluation is required.