High performance liquid chromatographic assay for the determination of Protease Inhibitors (PIs) and Non-nucleoside Reverse Transcriptase Inhibitors (NNRTIs) in human plasma.

Objective: To develop and validate a high performance liquid chromatography (HPLC) method for simultaneous quantitative determination of five HIV protease inhibitors (PIs): indinavir (IDV), lopinavir (LPV), nelfinavir (NFV), ritonavir (RTV), saquinavir (SQV), and two non-nucleoside reverse transcriptase inhibitors (NNRTIs): nevirapine (NVP), and efavirenz (EFV) in human plasma. Methods: A sample of 200 µL of plasma and an internal standard were extracted with tert-butyl methyl ether. The compounds were separated on a reversed-phase C18 column with gradient phase of 25 mM phosphate buffer (pH 4.9) and acetonitrile. The limit of quantation, accuracy, precision, specificity, stability and recovery were tested. Results: The lower limit of quantitation for all drugs was 75 ng/mL. The standard curve was linear in the range of 75 ng/mL to 20,000 ng/mL. Intra-day and inter-day variability ranged from 0.1% to 2.4% and 0.3% to 4.1%, respectively. Accuracy ranged from 98.4%-102.4% for three quality controls (75, 100, and 1,000 ng/mL) for all drugs measured. The extraction recovery ranged from 98.7%-101.3%. Conclusion: This method provides a simple, accurate, and precise method for monitoring of plasma concentrations of five PIs and two NNRTIs in the case of weak economy and out of date instrumental limitations.

Rapid determination of nevirapine in human plasma by high- performance liquid chromatography.

Objective: To develop and validate a high-performance liquid chromatography (HPLC) method for the determination of nevirapine in human plasma. Methods: A plasma sample and an internal standard were extracted with tert.-butyl methyl ether and determined nevirapine concentration by HPLC method. The limit of quantitation (LOQ), accuracy, precision, specificity, stability and recovery were tested for method validation. Results: Standard curve was linear in the range 0.1 ตg/mL to 20 ตg/mL. The limit of quantitation was 0.1 ตg/ml. Coefficients of variation (CV) of intraday and inter-day precision were less than 4 %. Accuracy was range from 97-101%. The extraction recovery was range from 94-112 %. Conclusion: A rapid, sensitive and specific HPLC method was developed and can be used for determination of plasma nevirapine concentration in adult and pediatric patients infected with HIV.

Treatment of paraquat poisoning with cyclophosphamide / dexamethasone combination: The first two years experience at Siriraj Hospital.

While the mortality rate from paraquat is high, a proven treatment for paraquat poisoning is still lacked. In this article, we describe the outcome of the first two years of implementing a treatment protocol containing cyclophosphamide and dexamethasone for paraquat poisoning at Siriraj Hospital. Treatment group was studied by a retrospective review of cases at Siriraj Hospital with significant paraquat poisoning in 2002-2003. Significant ingestion means ingestion of 1gram total or 20 mg/kg or positive urine dithionite test for paraquat. AII patients with significant ingestion received treatments with a regimen consisting of enteral administration of a single dose of Fuller’s earth solution and a 14-day course of intravenous cyclophosphamide plus intravenous dexamethasone plus intravenously vitamin C. Survival rate was compared with historical controls that included searchable cases with significant paraquat poisonings admitted to Siriraj Hospital who were treated only with Fuller’s earth or Bentonite, vitamins B and C and supportive care. From January 2002 to November 2003, there were 6 cases of significant paraquat poisoning presented to Siriraj Hospital. The survival rate of treatment group is 83.3% as judged by presence without life-threatening signs at 4 weeks after the ingestion. Nine cases of significant paraquat poisoning were identified from Siriraj Hospital’s searchable medical records from 1994-1997 and were enrolled as controls. AII control cases died within 12 days, six from fulminant paraquat poisoning and the remaining from moderate to severe poisoning. The use of immunosuppressive agents known for its ability to treat inflammatory lung disease such as cyclophosphamide and dexamethasone presents a viable alternative to an otherwise serious and untreatable poisoning.

Amikacin: Area under curve for once daily dose and its correlation with plasma concentration at six hours post infusion.

Aminoglycosides are commonly used for gram-negative septicemia. Formerly, peak and trough plasma levels were the monitoring parameters for conventional dose which was every eight hours. At present the recommended dose is once daily and the recommended monitoring parameters are the area under concentration time curve and the six-hour (range 146-180) for the area under curve and 6.79 milligrams per liter (range 5.6-7.9) for the six-hour plasma concentration post-infusion. The correlation of the area under curve and the six-hour plasma concentration post-infusion was reported in a linear equation with significance.

Comparison between real hospitalization benefits and reimbursements from diagnostic related group (DRG) criteria in HIV patients.

There are an increasing number of patients with the HIV virus in Thailand. The opportunistic infections in these patients are tuberculosis, Cryptococcal meningitis and Pneumocystis carinii pneumonia. The hospitalization benefits of admission were critical in the process of assessing of the economy of Thai government's budget. The coverage reimbursements from the government are classified according the criteria of the Diagnostic related group or DRG. An attempt to compare the real benefits to Siriraj Hospital and the government reimbursements for treating HIV-related illness was made and will eventually lead to further eventually adjustable reimbursements.

A drowsy patient with a positive purple urine test.

We report a pitfall in the investigation of amphetamine poisoning by urine test. A 21-year-old female who came to hospital with drowsiness and was reported to have positive purple urine test. This false positive urine test occurred as a result of drugs and substances of the same structure. Specific investigations were further recommended in order to detect the use of the amphetamines and allow appropriate treatment.

A fatal case of benzyl benzoate poisoning.

We present a case of benzyl benzoate ingestion in a 38 years old Thai woman whose presenting symptom was coma and severe metabolic acidosis. The amount ingested was 360ml of 25%W/V benzyl benzoate. It did not contain any alcohol or acid substance. Standard textbooks and other reference books do not mention severe symptoms caused by ingestion of given this substance and gastric lavage is the only recommendation. Should there be another method used to induce elimination of benzyl benzoate-hemodialysis?