Dynamics of serum concentrations of antibodies to infliximab: a new approach for predicting secondary loss of response in inflammatory bowel diseases.

BACKGROUND: Antibodies to infliximab (ATI) in serum are associated with secondary loss of response (LOR) to infliximab (IFX) therapy in patients with inflammatory bowel disease (IBD). However, feasible ATI-related predictors of therapy success are lacking and knowledge about individual ATI dynamics is limited. Therefore, this study analyzed whether ATI dynamics are able to predict LOR to IFX therapy and compared their predictive power with known predictors of LOR to IFX. METHODS: This was a retrospective study of patients with Crohn's disease (CD) or ulcerative colitis (UC) on IFX maintenance therapy and proactive IFX and immunogenicity monitoring in an outpatient clinic in Germany. Slopes of ATI (S ATI) and IFX levels (dynamic parameters) and medians of ATI, IFX, C-reactive protein, and fecal calprotectin (static parameters) were calculated over a defined period of time after ATI emergence. Dynamic and static parameters were analyzed for associations with end points infliximab discontinuation due to secondary LOR and total IFX discontinuation. RESULTS: In all, 500 visits from 38 IBD patients (28 CD, 10 UC) with a median IFX maintenance duration of 68.2 weeks were evaluated. Grouping by S ATI (ATI-N = ATI nondetectable, ATI- ↓ = negative S ATI, ATI- ↑ = positive S ATI) yielded significant differences for outcomes LOR (p = 0.004) and total IFX discontinuation (p = 0.01). Patients in the ATI-↓ group survived significantly longer LOR-free compared with the ATI-↑ group (p = 0.02). Cox regression confirmed S ATI to be a significant risk factor for LOR (p = 0.002). An S ATI cut-off of approximately 2.0 AU mL-1 week-1 was determined to predict LOR with 83.3% sensitivity and 93.8% specificity. CONCLUSION: The ATI slope-based index S ATI is a new feasible diagnostic predictor of LOR in IBD patients. S ATI may facilitate quick therapeutic decisions after ATI emerge.

Simultaneous determination of voriconazole and posaconazole concentrations in human plasma by high-performance liquid chromatography.

A simple, sensitive, and selective high-performance liquid chromatographic method for the simultaneous determination of voriconazole and posaconazole concentrations in human plasma was developed and validated. Quantitative recovery following liquid-liquid extraction with diethyl ether was achieved. Linearity ranged from 0.10 to 20.0 microg/ml for voriconazole and from 0.05 to 10.0 microg/ml for posaconazole. The intra- and interday coefficients of variation were less than 8.5%, and the lower limits of quantitation were <0.05 microg/ml.

High performance liquid chromatographic method for the determination of HIV-1 protease inhibitor tipranavir in plasma of patients during highly active antiretroviral therapy.

A new high-performance liquid chromatographic method for the determination of tipranavir in human plasma is described. Quantitative recovery following liquid-liquid-extraction with diethylether from 100 microl of human plasma was achieved. Subsequently, the assay was performed with 67 mM potassium dihydrogen phosphate-acetonitrile as a mobile phase, a Phenomenex C 18 column and UV detection at 255 nm. Linear Standard curves were obtained for concentrations ranging from 2.5 to 400 microg/ml. The calculated intra- and inter-day coefficents of variation were below 7%.

Safety of long-term lopinavir plasma-levels in patients with liver disease.

Chronic liver disease is often found in HIV infected patients. LPV as first choice drug is often used over long time periods. TDM as a tool in patients care is important but the knowledge of LPV-plasma-levels in patients with chronic liver disease remain uncertain. With this retrosepective analysis we want to show if there are differences in LPV-plasma-levels between patients with and without chronic liver diseases over a long-time period. LPV-plasma-levels were analysed with an HPLC-based methode. The LPV-plasma-levels over the time course in patients with chronic liver disease (n = 30) and patients without liver disease (n = 38) was evaluated. Liver function tests, CD4-cell count and HI-viral load was also correlated with liver disease. The LPV plasma-levels of n = 450 samples from 30 patients with liver disease (Hepatitis B: n = 17, Hepatitis C: n = 16, Alcoholic liver disease: n = 7) were determined over 18.7 +/- 16,3 months (1 - 48.5 months). A median of 10 samples per patient was eligible (2 - 50 samples). There are no significant differences according to liver disease in LPV-plasma levels (mean Ctrough without: 5917 +/- 4811 ng/ml, mean Ctrough with liver-disease: 6564 +/- 4517 ng/ml, p > 0.05). The intraindividual and interindividual variation of LPV-plasma levels, CD-4 increase, HI-virus suppression and liver tests in patients with and without liver disease is comparable. In this clinical setting no differences in LPV-plasma levels between patients with and without chronic liver disease could be demonstrated. LPV-therapy in patients with chronic liver disease is therefore safe. In patients with impaired liver function TDM is a helpful tool for dose adjustment.

No influence of the P-glycoprotein polymorphisms MDR1 G2677T/A and C3435T on the virological and immunological response in treatment naïve HIV-positive patients.

BACKGROUND: In a retrospective study of HIV-infected patients, we investigated the influence of the MDR1 genotype (G2677T/A and C3435T) on the virological and immunological response of treatment naive patients. METHODS: The MDR1 genotype was analysed from 72 patients in whom antiretroviral therapy was initiated between 1998 and 2004. Data were obtained at week 4, 12, 24 and 48 and were analysed by the Kruskal-Wallis test. RESULTS: During the first 48 weeks of antiretroviral therapy, there were no significant differences in the virological and immunological response with respect to the MDR1 2677 and 3435 genotypes and the 2677/3435 haplotype. CONCLUSIONS: In view of different results from several studies concerning the influence of MDR1 polymorphisms on the immunological and virological response to antiretroviral therapy, further studies with larger patient groups and longer follow-up are necessary in order to resolve conflicting issues.

Highly sensitive gas chromatographic determination of ethanol in human urine samples.

In order to evaluate recent alcohol consumption, a very sensitive and specific gas chromatographic method for ethanol determination in human urine samples was developed. The non-invasive method was performed without any pretreatment and carried out on a Stabilwax capillary column, 30 m x 0.53 mm x 1.0 microm film thickness. Helium was used as carrier gas with a constant inlet pressure of 27.72 kPa (0.277 bar) and a flame ionization detector (FID). Quantification was performed with the use of acetonitrile as an internal standard (IS). The calibration curve was linear throughout the concentration range from 0.5 to 500 mg/l. The calculated intra- and inter-day coefficients of variation were below 8%. A clear chromatographic separation of ethanol from methanol, acetone, 1-propanol and 2-propanol was achieved.

Rapid determination of nevirapine in human plasma by gas chromatography.

A sensitive and rapid gas chromatographic method has been developed to determine the levels of the HIV-1 non-nucleoside reverse transcriptase inhibitor nevirapine in human plasma. Quantitative recovery following liquid-liquid-extraction with diethylether from 500 microl of human plasma was achieved. Subsequently, the assay was performed with a CP-Sil 5CB capillary column, 15 m x 0.32 mm x 1.0 microm film thickness with a nitrogen-phosphorous-detector (NPD), Helium 5.0 was used as carrier gas with a constant inlet pressure of 7 p.s.i. Linear standard curves were obtained for concentrations ranging from 10 to 20 000 ng/ml. The calculated intra- and inter-day coefficients of variation were below 8%.

Follow-up measurements of Nevirapine plasma levels over a prolonged period.

Over a period of more than four years of treatment, 177 Nevirapine plasma levels were taken from 27 patients. The values showed a high inter-patient variability and a lower intra-patient variability. Differences in body weight turned out to be the main reason for inter-patient variability. Treatment over a prolonged period did not result in any change in plasma concentrations. Adjusting dosage by means of therapeutic drug monitoring would appear to be a reasonable way of maximising patient benefit from treatment.

High-performance liquid chromatographic method for the determination of sorafenib in human serum and peritoneal fluid.

PURPOSE: Sorafenib is recommended for therapy of advanced hepatocellular carcinoma and renal cell carcinoma. Preclinical data indicate a relation between dose and antitumor efficacy. In clinical trials, adverse events improve after dose reduction suggesting a dose-dependent toxicity. Given dose has a direct impact on the drug serum concentration, but the latter also can be influenced by multiple factors, including interaction and metabolisation. To enable the investigation of concentration-related effects, an easy and sensitive assay for sorafenib drug monitoring is essential. METHODS: A high-performance liquid chromatography (HPLC) analysis involving an extraction with diethyl ether followed by separation on a Pinnacle™ DB C18 column and quantitation by UV absorbance at 260 nm was established. Sorafenib concentrations in samples of serum and peritoneal fluid have been determined. RESULTS: The assay was validated for serum samples and is linear over the concentration range of 100-5,000 ng/ml with a determination coefficient of >0.999. The limit of detection is 0.25 ng/ml. The intra- and inter-day coefficients of variation were below 3.03%. Sorafenib recovery in spiked probes of peritoneal fluid was above 85%. Sorafenib concentrations in 44 serum samples and 14 probes of peritoneal fluid have been determined with a mean of 3,328 and 1,380 ng/ml, respectively (standard deviation 2,267 and 659 ng/ml). CONCLUSIONS: A sensitive and selective HPLC method for the determination of sorafenib in human serum was developed and also verified for peritoneal fluid. This method provides a useful tool for pharmacokinetic investigations as well as for therapeutic drug monitoring of sorafenib.

Epidural spinal lipomatosis with acute onset of paraplegia in an HIV-positive patient treated with corticosteroids and protease inhibitor: case report.

STUDY DESIGN: Case report. OBJECTIVE: To report a case of HIV-related lipodystrophy with a rapid onset of symptoms from epidural lipomatosis in the wake of protease inhibitor and steroid treatment. SUMMARY OF BACKGROUND DATA: Symptomatic spinal epidural lipomatosis is considered to be a rare condition usually presenting with slowly progressive cord or nerve root compression. Only 2 cases of spinal lipomatosis in HIV-related lipodystrophy have been reported. METHODS: We describe the case of a 41-year-old male with HIV who received protease inhibitor medication and had neurologic deficits rapidly develop. RESULTS: The patient had complete paraplegia develop within 12 hours from admission following a 1-day history of unsteady gait and a 3-day history of leg numbness. After diagnosis of epidural lipomatosis on magnetic resonance imaging, the patient underwent decompressive thoraco-laminectomy. He recovered well and was able to walk by postoperative day 4. CONCLUSION: It is important to maintain an awareness for the possible association between HIV lipodystrophy and symptomatic epidural lipomatosis.

Drug monitoring of pyrimethamine during maintenance therapy of toxoplasmic encephalitis in patients with advanced HIV infection during HAART.

BACKGROUND: Prophylaxis of toxoplasmic encephalitis was performed with pyrimethamine in 6 patients with advanced HIV infection during combination therapy with protease inhibitors. MATERIAL/METHODS: Steady-state plasma pyrimethamine (PYR) levels were measured by gas chromatography. Protease inhibitor plasma concentrations were analyzed trough concentration by high pressure liquid chromatography. During a treatment period of 22I13 months a total of 93 samples from 6 patients were investigated, containing pyrimethamine and protease inhibitors. RESULTS: The mean pyrimethamine concentration was 1,108+/-459 ng/ml with a dosage of 37.5 mg/d and 1, 685+/-665 ng/ml with 50 mg/d. With the simultaneous use of indinavir (IDV), a mean pyrimethamine concentration of 2,165+/-273 ng/ml was found, significantly higher than in combination with saquinavir (SQV) and ritonavir (RTV) (1,192+/-178 ng/ml) or saquinavir and nelfinavir (NLV) (1,117+/-173 ng/ml). This effect was not considered clinically significant. Drug monitoring of protease inhibitors revealed a wide range of protease inhibitor levels. CONCLUSIONS: The statistically significant lower PYR concentrations with the SQV + RTV or SQV + NLV comedication in comparison to comedication with IDV were not considered clinically significant. Therapeutic drug monitoring of PYR and PI plasma levels can be recommended in patients during therapy with both PYR and PI, especially during therapy with a double PI regimen.

Osteomyelitis and skin ulcers caused by Mycobacterium szulgai in an AIDS patient.

Mycobacterium szulgai is a ubiquitious non-tuberculous mycobacterium causing infection in immunocompetent and immunocompromized patients. Clinically mimicking pulmonary tuberculosis in most cases described, rarely other manifestations occur. Here we report the case of an AIDS patient with osteomyelitis of the hand and toe, accompanied by multiple cutaneous ulcers of the chest and forearm. The case highlights the unusual combination of osteomyelitis and skin ulcers without pulmonary infection and describes the likely cutaneous route of infection in a patient who keeps tropical fish.