Quantitative pp65-antigenemia assay for the prediction of human cytomegalovirus disease in HIV-infected patients

OBJECTIVE

To evaluate the ability of a quantified pp65-antigenemia assay to predict the development of human cytomegalovirus (HCMV) disease in patients with an advanced HIV infection.

DESIGN

A prospective longitudinal study between March 1993 and December 1996. Blood samples for the pp65-antigenemia assay were drawn at 2-3 month intervals.

SETTING

AIDS department of an institutional tertiary care centre.

PATIENTS

A total of 101 HIV-infected patients with CD4 lymphocyte counts of 100/mm3 or less were enrolled. Ninety-seven patients were eligible for analysis. All patients gave informed consent.

MAIN OUTCOME MEASURES

The development of HCMV disease.

RESULTS

Of the 97 patients, 24 developed HCMV disease after a median follow-up of 10.6 months. Three months before the development of HCMV disease, an increase in the median number of pp65-antigen-positive leukocytes was observed. The highest combination of sensitivity (45%) and specificity (94%) for the development of HCMV disease within the next 3 months was found when an assay cut-off level of 48/10(5) pp65-antigen-positive leukocytes was applied, with a positive predictive value (PPV) for the development of HCMV disease of 75%. The Kaplan-Meier estimate of HCMV disease-free survival after patients reached 48/10(5) or more antigen-positive leukocytes on longitudinal follow-up was a median 3.7 months [95% confidence interval (CI), 2.5-8.5]. The hazard ratio (HR) of this threshold level for the development of HCMV disease was 9.6 (95% CI, 4.2-21.8).

CONCLUSION

Longitudinal follow-up using the pp65-antigenemia assay of HIV-infected patients with a low CD4 lymphocyte count improves the identification of patients who will develop HCMV disease in the foreseeable future, and should be considered for the selection of patients who may benefit from pre-emptive HCMV treatment.

Quantitative determination of efavirenz (DMP 266), a novel non-nucleoside reverse transcriptase inhibitor, in human plasma using isocratic reversed-phase high-performance liquid chromatography with ultraviolet detection

Efavirenz is a novel non-nucleoside reverse transcriptase inhibitor for the treatment of HIV-1-infected individuals. A simple and rapid high-performance liquid chromatographic method for the quantification of efavirenz in human plasma suitable for therapeutic drug monitoring in plasma is described. Sample pretreatment consists of protein precipitation with acetonitrile and subsequent evaporation of the extract to concentrate the analyte. The drug is separated from endogenous compounds by isocratic reversed-phase high-performance liquid chromatography with ultraviolet detection at 246 nm. The method has been validated over the range of 10 to 10,000 ng/ml using a volume of 250 microl of plasma. The assay is linear over this concentration range as indicated by the F-test for lack of fit. Within- and between-day precisions are less than 4.3% for all quality control samples. The lower limit of quantitation is 10 ng/ml and the recovery of efavirenz from human plasma is 106.4% (+/- 1.8%). Frequently co-administered drugs did not interfere with the described methodology. Efavirenz is stable under various relevant storage conditions, for example when stored for 24 h at room temperature. This validated assay is suited for use in pharmacokinetic studies with efavirenz and can readily be implemented in the setting of a hospital laboratory for the monitoring of efavirenz concentrations.

The steady-state plasma pharmacokinetics of indinavir alone and in combination with a low dose of ritonavir in twice daily dosing regimens in HIV-1-infected individuals

OBJECTIVE

To explore the steady-state plasma pharmacokinetics of indinavir in twice daily dosing regimens with and without the co-administration of 100 mg ritonavir.

DESIGN

Observational pharmacokinetic study.

PATIENTS

HIV-1-infected individuals who use indinavir alone (1200 mg twice daily, n = 6), or the combination of 100 mg ritonavir twice daily plus either 800 mg (n = 6), or 1200 mg indinavir twice daily (n = 2).

METHODS

Steady-state pharmacokinetics of indinavir and ritonavir were assessed by drawing 12 blood samples during an 8-h period after ingestion of the medication.

RESULTS

Significant differences were observed for indinavir pharmacokinetics between the dosing regimens indinavir 1200 mg twice daily alone and indinavir/ ritonavir 800/100 mg twice daily with respect to the mean trough concentration (0.21 and 0.99 microg/ml, respectively, P = 0.002), the mean maximum concentration (13.79 and 8.74 microg/ml, respectively, P = 0.028), and for the mean plasma elimination half-life (1.6 and 3.2 h, respectively, P = 0.001). The combination indinavir/ritonavir 1200/100 mg twice daily led to very high exposure to indinavir and was not well tolerated. However, the combination indinavir/ritonavir 800/100 mg twice daily was well tolerated and resulted in therapeutic concentrations of indinavir with improved trough concentrations and similar maximum concentrations as observed with the licensed dosage of 800 mg three times daily.

CONCLUSION

Combination of indinavir and 100 mg ritonavir in twice daily dosing regimens significantly affects the pharmacokinetic profile of indinavir. The results of this observational study provide a pharmacologic basis for the combination of indinavir (800 mg) and ritonavir (100 mg) in twice daily dosing regimens.

Immune reconstitution after 2 years of successful potent antiretroviral therapy in previously untreated human immunodeficiency virus type 1-infected adults

Today's antiretroviral combination regimens can induce significant and sustained decreases in human immunodeficiency virus (HIV)-RNA levels, allowing the immune system to recover. To what extent immune reconstitution is possible and what factors determine the outcome have thus far not been resolved. We studied 19 subjects, treated for 2 years with protease inhibitor-containing triple therapy, who had a strong suppression of HIV-RNA levels. CD4+ T-cell numbers increased from medians of 170 to 420x106 cells/L, but in a number of subjects T-cell numbers did not further increase after week 72, without having reached normal values. Long-term CD4+ T-cell change was mainly caused by a slow but continuous increase in naive CD4+ T cells (CD45RA+CD62L+) and was predicted by the baseline number of these cells. Our data indicate that long-term immunological recovery is gradual, even during strong suppression of viral replication, not always complete, and dependent on the preexisting level of naive CD4+ T cells.

Monitoring of epstein-barr virus DNA load in peripheral blood by quantitative competitive PCR

A competitive quantitative PCR (Q-PCR) assay combined with simple silica-based DNA extraction was developed for monitoring of Epstein-Barr virus (EBV) DNA load in unfractionated peripheral blood. The Q-PCR is based on competitive coamplification of a highly conserved 213-bp region of the EBNA-1 open reading frame with an internal standard (IS), added in a known concentration. The IS has the same amplicon length and base composition as the wild-type (WT) EBNA-1 amplicon but differs in 23 internally randomized bases. Competitive coamplification yields two PCR products that are quantified by enzyme immunoassay or by electrochemiluminescence detection, with probes specific for the 23 differing internal nucleotides. The Q-PCR has a sensitivity of 10 copies of either WT or IS plasmid DNA. The Q-PCR was validated by quantification of known amounts of plasmid containing the WT EBNA-1 target. Furthermore, we determined EBV genome copy numbers in different cell lines. For EBV quantification in clinical samples, DNA was isolated from lysed whole blood by silica-affinity purification. Forty-six percent of healthy donor peripheral blood samples were positive by Q-PCR. In most of these samples, viral load was less than 2,000 EBV copies/ml of blood. In peripheral blood samples from two AIDS-related non-Hodgkin's lymphoma patients, elevated EBV loads (up to 120,000 copies/ml) were observed, which decreased upon therapy. In Burkitt's lymphoma patients, up to 4,592,000 EBV genome copies/ml of blood were detected. In conclusion, the EBNA-1-based Q-PCR assay provides a reproducible, accurate, and easy method for studying the relationship between EBV load and clinical parameters.

Paclitaxel in the treatment of human immunodeficiency virus 1-associated Kaposi's sarcoma--drug-drug interactions with protease inhibitors and a nonnucleoside reverse transcriptase inhibitor: a case report study

PURPOSE

To describe the pharmacokinetics of paclitaxel and to investigate the interaction potential with protease inhibitors (indinavir, ritonavir, saquinavir) and the nonnucleoside reverse transcriptase inhibitor nevirapine, for which strong theoretical indications for clinically relevant drug interactions exist.

METHODS

The 24-h plasma pharmacokinetics of paclitaxel (Taxol, given at 100 mg/m2 by 3-h intravenous infusion) and concomitantly infused antiretroviral drugs were determined in a human immunodeficiency virus 1 (HIV-1)-infected male patient with refractory Kaposi's sarcoma (KS) during high-activity antiretroviral therapy and after discontinuation of this regimen. The plasma pharmacokinetics of paclitaxel, indinavir, ritonavir, saquinavir, and nevirapine were closely monitored. Since all these drugs are extensively metabolized via the cytochrome P450 enzyme system and are substrates for the multidrug transporter P-glycoprotein, investigation of drug-drug interactions was considered important.

RESULTS

In this case report study the pharmacokinetics of paclitaxel given concomitantly with various antiretroviral drugs were comparable with those of historical controls who had been treated with single-agent paclitaxel. The pharmacokinetics of indinavir, ritonavir, saquinavir, and nevirapine were also not statistically significantly different from those recorded for historical controls. Paclitaxel was well tolerated and resulted in a significant clinical response in this patient.

CONCLUSION

Dose adjustments of paclitaxel, indinavir, ritonavir, saquinavir, or nevirapine are apparently not needed if HIV-1-associated KS is treated with paclitaxel at a dose of 100 mg/m2 as shown in the present case. It is stressed, however, that controlled studies are necessary to substantiate these preliminary case report findings.

Randomized trial comparing saquinavir soft gelatin capsules versus indinavir as part of triple therapy (CHEESE study)

OBJECTIVE

To compare efficacy and tolerability of saquinavir soft gelatin capsule (SQV-SGC) formulation and indinavir, both given as part of a triple drug regimen containing zidovudine and lamivudine, in HIV-1-infected individuals.

DESIGN

Randomized, open label, multicentre study.

PATIENTS

A total of 70 patients who were antiretroviral-naive and who had a CD4 cell count < 500 x 10(6)/I and/or > 10000 HIV RNA copies/ml plasma and/or HIV-related symptoms. Subjects were assigned randomly to zidovudine 200 mg three times per day plus lamivudine 150 mg twice per day plus either SQV-SGC 1200 mg three times per day (SQV-SGC group) or indinavir 800 mg three times per day (indinavir group). Data are presented for all patients up to week 24.

RESULTS

Mean baseline CD4 cell counts (+/- SE) were 301+/-29 x 10(6) cells/l and 310 +/-43 x 10(6) cells/l in the SQV-SGC and indinavir groups, respectively. The log10 median baseline HIV RNA load was 5.00 copies/ml in the SQV-SGC group and 4.98 copies/ml in the indinavir group. No difference in antiretroviral effect between the treatment arms could be demonstrated. Intention-to-treat analysis (last observation carried forward [LOCF]) at week 24 revealed that RNA levels decreased to < 50 copies/ml in 74.3% of patients in the SQV-SGC group and in 71.4% of the patients in the indinavir group (P = 0.78). In the on-treatment analysis the proportion of patients < 50 copies/ml at week 24 was 88.0% in the SQV-SGC group and 84.6% in the indinavir group (P = 0.725). Intriguingly, the mean increase of CD4 cells in the first 24 weeks was 162+/-20 x 10(6) cells/l in the SQV-SGC group and 89+/-21 x 10(6) cells/l in the indinavir group (P = 0.01), but preliminary data indicate that this difference in CD4 cell count gain may disappear after 24 weeks of treatment. Both regimens were generally well tolerated.

CONCLUSION

During the first 24 weeks of the study, we found no difference in antiviral potency between the indinavir group and the SQV-SGC group. A significantly higher CD4 response in the SQV-SGC group was observed.

Rapid quantification of delavirdine, a novel non-nucleoside reverse transcriptase inhibitor, in human plasma using isocratic reversed-phase high-performance liquid chromatography with fluorescence detection

Delavirdine is a novel non-nucleoside reverse transcriptase inhibitor for the treatment of HIV-1-infected patients. A simple and rapid high-performance liquid chromatographic method for the quantification of delavirdine in human plasma suitable for drug monitoring in patients is described. Sample pretreatment consists of protein precipitation with acetonitrile and subsequent evaporation of the extract to concentrate the analyte. The drug is separated from endogenous compounds by isocratic reversed-phase, high-performance liquid chromatography coupled with fluorescence detection. The optimal excitation and emission wavelengths are 300 and 425 nm, respectively. The method has been validated over the range of 50-50 000 ng/ml using only 200 microl of plasma samples. The assay is linear over this concentration range as indicated by the F-test for lack of fit. Within- and between-day precisions are less than 4.4% for all quality control samples. The lower limit of quanititation is 50 ng/ml. Recovery of delavirdine from human plasma is 93.8%. Delavirdine is stable under various conditions, for example 1 h at 60 degrees C and one week at 4 degrees C. This validated assay is suited for use in pharmacokinetic studies with delavirdine and can readily be implemented in the setting of a hospital laboratory for the monitoring of delavirdine concentrations.

Immunopathology as a result of highly active antiretroviral therapy in HIV-1-infected patients

OBJECTIVE

Unusual clinical inflammatory syndromes associated with underlying previously unrecognized opportunistic infections are increasingly being noted shortly after starting highly active antiretroviral therapy (HAART). This study examined the possible relationship between such unexpected disease manifestations and in vitro parameters of microbial antigen-specific immune reactivity in patients infected with HIV-1 who had a Mycobacterium avium intracellulare or Mycobacterium xenopi infection.

DESIGN

In vitro T-cell proliferation experiments were performed after specific stimulation of a patient's peripheral blood mononuclear cells (PBMC) with M. avium and M. xenopi antigen and non-specific stimulation with phytohaemagglutinin (PHA). The results were compared with appropriate controls.

PATIENTS

Five patients who presented with unusual clinical syndromes associated with M. avium or M. xenopi infection within weeks of experiencing large rises in CD4+ cell counts following the initiation of antiretroviral therapy.

RESULTS

In all patients except one, mycobacteria-specific lymphoproliferative responses rose significantly following HAART; this was temporally associated with elevations in CD4+ cell counts and the occurrence of clinical disease. The patient with M. xenopi infection appeared to clear his infection subsequently without antimycobacterial therapy. In three of the four patients with M. avium infection, antimycobacterial treatment could be stopped without recurrence of infection.

CONCLUSION

Our findings support the hypothesis that HAART may lead to clinically relevant inflammation as a result of restoration of specific immune reactivity against microbial pathogens that are subclinically present at the time treatment is initiated. Continuation of HAART may subsequently result in protective immunity and clearance of infection.

Survival after massive ecstasy overdose

INTRODUCTION

The toxicity profile of the amphetamine derivative 3,4-methylenedioxymethamphetamine (MDMA, "Ecstasy") is well known. This designer drug is usually taken at "house parties" and may cause severe complications, sometimes leading to death, even when taken in relatively small units (1 or 2 tablets). Up to now, only a few cases of survival after ingestion of an overdose of Ecstasy have been described. In most cases the users developed hyperthermia, disseminated intravascular coagulation, rhabdomyolysis, and renal failure.

CASE REPORT

We describe a man who, after ingesting 50 tablets of Ecstasy (in combination with oxazepam and alcohol) at home, recovered within 2 days. Presenting features were unconsciousness, apnea, and convulsions. It is suggested that in most cases severe 3,4-methylenedioxymethamphetamine toxicity results from an interaction between direct pharmacological effects of the drug and the prevailing environmental conditions (high ambient temperature, dancing in trance, little fluid intake).

Comparison of the plasma pharmacokinetics and renal clearance of didanosine during once and twice daily dosing in HIV-1 infected individuals

OBJECTIVE

To compare the plasma pharmacokinetics of didanosine during once daily (qd) and twice daily (bid) dosing.

DESIGN

Open-label, randomized, cross-over study.

METHODS

HIV-1 infected patients who used didanosine were randomized to either a qd or a bid dosing regimen of didanosine. The total daily dose of didanosine was identical in both regimens. Seven days after the start of the study, the pharmacokinetic profile of didanosine in plasma and urine was assessed during an 8-h period. The next day, the patient was switched to the opposite dosing regimen, and after another 7 days, the study was concluded by again assessing the plasma and urine pharmacokinetics of didanosine during 8 h.

RESULTS

A total of 19 patients completed the study. The pharmacokinetics of didanosine in plasma (with maximum plasma concentration adjusted for dose) and urine were not significantly different in the qd and bid dosing regimen (P > 0.28 for all parameters).

CONCLUSION

We conclude that qd dosing of didanosine leads to a similar exposure in plasma as bid dosing (using the same total daily dose). Since qd dosing may lead to improved compliance of patients to regimens containing didanosine, these results provide a rationale for prescribing didanosine in a qd regimen, and is reassuring when we realize that the drug is being administered in a qd dosing regimen on a large scale in clinical practice.

Co-trimoxazole and stavudine interference in a high-performance liquid chromatographic analysis for didanosine in human plasma

Recently, the authors were confronted with interference of stavudine and co-trimoxazole when analyzing the antiretroviral drug didanosine (ddI) in plasma of HIV-1-infected patients using reverse-phase high-performance liquid chromatography with ultraviolet detection. After increasing the percentage of methanol in the mobile phase from 4% to 8% vol/vol and after decreasing the pH of the mobile phase from 6.8 to 5.8, the authors were able to separate didanosine from stavudine and co-trimoxazole (both are frequently used drugs in combination with didanosine). Subsequently, the adapted bioanalytic methodology was validated, and validation results showed that this new methodology can be used for the quantitative determination of didanosine in human plasma. This observation makes clear that combination therapy for human immunodeficiency virus with multiple (often chemically related) drugs has the potential of unexpectedly complicating bioanalytic analyses because therapeutic strategies may change rapidly after publication of a bioanalytic methodology. Thus, it is evident that the investigation of interference of potentially coadministered drugs should be a standard procedure during the development of any bioanalytical methodology in any laboratory.

Simultaneous quantitative determination of the HIV protease inhibitors amprenavir, indinavir, nelfinavir, ritonavir and saquinavir in human plasma by ion-pair high-performance liquid chromatography with ultraviolet detection

A reversed-phase high-performance liquid chromatographic assay for the simultaneous quantitative determination of five HIV protease inhibitors (i.e. amprenavir, indinavir, nelfinavir, ritonavir, and saquinavir) in human plasma is described. Sample pretreatment consisted of solid-phase extraction prior to ion-pair, reversed-phase high-performance liquid chromatography with ultraviolet detection at 210 nm (amprenavir, indinavir and nelfinavir) and 239 nm (saquinavir and ritonavir). For amprenavir, indinavir and saquinavir the method has been validated over the range of 25 ng/ml to 25 microg/ml using a 0.6 ml sample volume. For nelfinavir and ritonavir the method has been validated over the range of 50 ng/ml to 25 microg/ml. The method proved to be accurate, with an average accuracy at four concentrations ranging from 90.6 to 109.2%, and precise, with the within-day and between-day precision ranging from 1.8 to 6.7%, and 0.7 to 7.6%, respectively. The protease inhibitors which can be quantified by using this assay proved to be stable under various conditions. This assay can readily be used in a hospital laboratory for the routine monitoring of plasma concentrations of these protease inhibitors.

Rapid determination of nevirapine in human plasma by ion-pair reversed-phase high-performance liquid chromatography with ultraviolet detection

Nevirapine is a non-nucleoside reverse transcriptase inhibitor for the treatment of HIV-1-infected patients. A simple and rapid high-performance liquid chromatographic method for the quantification of nevirapine in human plasma is described. Sample pretreatment consists of protein precipitation with acetonitrile. The analyte is separated from endogenous compounds by isocratic reversed-phase, ion-pair, high-performance liquid chromatography with ultraviolet detection at 282 nm. The method has been validated over the range of 52-10400 ng/ml using 250 microl of plasma. The assay was linear over this concentration range. Within- and between-day precisions were less than 4.5% for all quality control samples. The lower limit of quantitation was 52 ng/ml. Recovery of nevirapine from human plasma was 94.5%. This validated assay is suited for use in pharmacokinetic studies with nevirapine and can readily be used in a hospital laboratory for the monitoring of nevirapine concentrations.

A dose-dependent delayed hypersensitivity reaction to acetaminophen after repeated acetaminophen intoxications

We report a case of a 29-year-old woman with a borderline personality disorder who presented with intentional substantial acetaminophen (paracetamol) overdosage on nine occasions during a period of 21 months. In most cases, the patient presented at the hospital within 4 h after ingestion and was treated with gastric lavage, activated charcoal, laxatives and intravenous N-acetylcysteine. During the sixth overdosage the patient developed a rash on her chest and shoulders which was considered an anaphylactoid reaction to N-acetylcysteine. Therefore she was treated with oral methionine subsequently, but developed the rash again. The rash was then ascribed to the repeated high-doses of acetaminophen and treatment with N-acetylcysteine was reinstituted. This case shows that when an anaphylactoid reaction occurs after an acetaminophen overdose and treatment with N-acetylcysteine, acetaminophen must also be taken into account as the cause of the anaphylactoid reaction before effective therapy with N-acetylcysteine is withheld.

High-performance liquid chromatographic determination of ritonavir in human plasma, cerebrospinal fluid and saliva

A simple, ion-pair high-performance liquid chromatographic method has been developed and validated for the quantitative determination of the HIV protease inhibitor ritonavir in human plasma, cerebrospinal fluid and saliva. Sample pretreatment consisted of precipitation of proteins with acetonitrile prior to high-performance liquid chromatography with ultraviolet detection at 239 nm. The method has been validated over the range of 50 ng/ml to 50 microg/ml with use of 100-microl volumes of sample. The currently described assay has been used successfully for the analysis of ritonavir in plasma, cerebrospinal fluid and saliva in HIV-1 infected patients.

Decrease of HIV-1 RNA levels in lymphoid tissue and peripheral blood during treatment with ritonavir, lamivudine and zidovudine. Ritonavir/3TC/ZDV Study Group

OBJECTIVES

Triple combination treatment of HIV-1 infection using two reverse transcriptase inhibitors and a protease inhibitor can result in significant and sustained decreases in the quantity of viral RNA in peripheral blood. Lymphoid tissue, however, constitutes the major reservoir of HIV in infected patients. Study of the viral burden in these tissues has provided additional insight in the efficacy of antiretroviral treatment.

DESIGN

Patients were randomized into two groups in order to study differences in the development of resistance to reverse transcriptase inhibitors. Group I started treatment with all three drugs simultaneously. Group II started with ritonavir monotherapy, aiming at initial reduction in virus production before the addition of lamivudine and zidovudine 3 weeks later.

METHODS

Changes in the amount of HIV in plasma and tonsillar lymphoid tissue during 24 weeks of treatment with ritonavir, lamivudine and zidovudine were studied by reverse transcriptase polymerase chain reaction.

RESULTS

Thirty-three antiretroviral-naive HIV-infected patients were included for analysis. After 24 weeks, median CD4+ cell count increased by 152 x 10(6)/l and median plasma viral RNA levels decreased by at least 2.87 log10 copies/ml. In 88% of the patients remaining on treatment, plasma RNA levels were below the quantification limit of the assay used (mean, 2.4 log10 copies/ml). The lymphoid tissue viral burden, ranging from 9.16 to 8.52 log10 copies/g at baseline, was markedly reduced with at least 2.1 log10 copies/g by week 24 in the five patients analysed. Eight patients (24%) withdrew because of side-effects. In one patient in group II, ritonavir and lamivudine resistance-associated mutations developed.

CONCLUSIONS

Treatment with this triple antiretroviral drug combination produced a durable and strong decrease of HIV-1 RNA burden in both plasma and lymphoid tissue.

Improvement of chronic diarrhoea in patients with advanced HIV-1 infection during potent antiretroviral therapy

BACKGROUND

A substantial number of patients with advanced HIV infection suffer from intractable diarrhoea. The aim of this study was to evaluate whether potent antiretroviral therapy could alleviate such diarrhoea.

METHODS

In an open randomized study the effect of the HIV protease inhibitor indinavir in combination with nucleoside analogue reverse transcriptase inhibitors on chronic HIV-related diarrhoea was investigated in 14 late-stage (CD4+ lymphocyte count < or = 50 x 10(6) cells/l) HIV-infected patients. Data concerning stool frequency, stool consistency and antidiarrhoeal drug use were collected in daily diaries over a 24-week period. Endpoints of the study were reduction of stool frequency, improvement of stool consistency, weight gain, and in case of diarrhoea due to Enterocytozoon bieneusi or Cryptosporidium sp. disappearance of these parasites from stool.

RESULTS

Thirteen patients started the study drug indinavir. One patient died after 1 week and one patient withdrew prematurely after 18 weeks. Median stool frequency declined from 5.8 daily at baseline to 2.3 daily after 24 weeks (P=0.04). Stool consistency improved considerably over the study period: before treatment 56% of stools were watery and 0% were formed; at week 24 these figures were 0 and 35%, respectively. Body weight increased significantly with a median increment of 6.6 kg at week 24 (P=0.0006). In two out of six patients with microsporidiosis and both patients with cryptosporidiosis, stools were free of parasites at week 24. Five out of six patients who used non-specific antidiarrhoeal medication on a regular basis prior to the study had ceased to do so at the end.

CONCLUSION

The use of potent antiretroviral therapy in patients with advanced HIV infection can improve chronic HIV-related diarrhoea and in some cases lead to disappearance of E. bieneusi and Cryptosporidium sp. from the stools.

Determination of saquinavir in human plasma, saliva, and cerebrospinal fluid by ion-pair high-performance liquid chromatography with ultraviolet detection

A high-performance liquid chromatographic method for the determination of the HIV protease inhibitor saquinavir in human plasma, saliva, and cerebrospinal fluid is described. Saquinavir was extracted from samples using C2 extraction columns prior to ion-pair, reversed-phase high-performance liquid chromatography with ultraviolet detection at 239 nm. The method has been validated over the range of 2.5-4000 ng/ml using a 0.6-ml sample volume. This assay has been used for the analysis of saquinavir in plasma and saliva of HIV-1-infected patients.

Clinical pharmacology of HIV protease inhibitors: focus on saquinavir, indinavir, and ritonavir

In this review the clinical pharmacology of HIV protease inhibitors, a new class of antiretroviral drugs, is discussed. After considering HIV protease function and structure, the development of inhibitors of HIV protease is presented. Three protease inhibitors are reviewed in more detail: saquinavir, indinavir, and ritonavir. Clinical trial results with these agents are evaluated. Furthermore, adverse effects, resistance, dosage and administration, clinical pharmacokinetics, pharmacokinetic-pharmacodynamic relationships, and drug interactions are discussed.

Clinically relevant drug interactions with antiretroviral agents

With the advent of the human immunodeficiency virus (HIV) protease inhibitors and the non-nucleoside reverse transcriptase inhibitors, the importance of drug-drug interactions with antiretroviral agents is becoming increasingly recognized. Every clinician involved in the care of HIV-infected persons should have a broad knowledge of these drug-drug interactions and their underlying mechanisms. This paper will review currently known clinically relevant interactions with antiretroviral agents reported thus far. Alternative strategies will be proposed where possible, in order to improve patient safety and the therapeutic efficacy of the antiretroviral agents. It must be emphasized, however, that in many cases these proposals are not backed up by authoritative clinical consensus panels and that clinical experience with many of these combinations is limited.

Penetration of 3'-amino-3'-deoxythymidine, a cytotoxic metabolite of zidovudine, into the cerebrospinal fluid of HIV-1-infected patients

The penetration of 3'-amino-3'-deoxythymidine (AMT) into the cerebrospinal fluid (CSF) of HIV-1-infected patients has been investigated. In 23 patients who used zidovudine (ZDV) chronically, CSF and plasma samples were assayed for AMT and ZDV. The influences of time between ZDV oral administration and lumbar puncture, of ZDV dose, and of the medical indication for lumbar puncture based on the concentration of AMT in CSF and on the CSF-plasma concentration ratio were investigated. AMT can be detected in the CSF after oral administration of ZDV; concentrations of AMT in CSF ranged from 0.75 to 4.8 ng/ml (median, 1.7 ng/ml). The median CSF-plasma concentration ratio was 1, and equaled that for ZDV. CSF and plasma concentrations of AMT were approximately threefold higher in patients with cerebral toxoplasmosis; the CSF-plasma concentration ratio remained equal to unity in these cases. This phenomenon might be caused by a pharmacokinetic interaction between AMT and pyrimethamine, sulfadiazine, folinic acid, or a combination of these. The clinical relevance of AMT, especially the possibility of decreased efficacy of ZDV, throughout the body and in the central nervous system, and the involvement of this metabolite in ZDV-induced myelosuppression, remains to be established.

HIV-1 RNA levels in the cerebrospinal fluid may increase owing to damage to the blood-brain barrier

Human immunodeficiency virus type 1 (HIV-1) RNA can be detected in the cerebrospinal fluid (CSF) of 75-90% of all HIV-infected patients. However, it is not yet known which factors influence the amount of HIV-1 in the CSF, either qualitatively or quantitatively. We have analysed HIV-1 RNA in CSF samples from 24 HIV-infected patients using zidovudine who underwent lumbar puncture in order to establish a diagnosis for a neurological disorder. Several factors were examined for possible correlation with the amount of HIV-1 RNA in the CSF: age, gender, the medical indication for lumbar puncture, the most recent CD4 cell count in blood, zidovudine dose, duration of treatment with zidovudine, the zidovudine concentration in plasma and CSF, and the total protein concentration in plasma and CSF. The only statistically significant factor was the total protein level in the CSF, which showed a positive relation with the amount of HIV-1 RNA in the CSF. This study indicates that increased levels of HIV-1 RNA in the CSF of neurologically symptomatic patients are the result of damage to the blood-brain barrier.

Pharmacokinetics of fluconazole in saliva and plasma after administration of an oral suspension and capsules

The concentrations of fluconazole were determined at steady state in the saliva and plasma of 10 healthy volunteers after ingestion of fluconazole as capsules and after flushing the mouth for 2 min with the same dose formulated as an oral suspension and swallowing of the drug. Saliva and plasma samples were analyzed by a validated high-performance liquid chromatographic assay. Flushing and swallowing of the oral suspension resulted in a significantly (P = 0.005) higher mean area under the concentration-versus-time curve (AUC) from 0 to 24 h in saliva (89.13 +/- 23.42 mg.h/liter) than that obtained after ingestion of the same dose as capsules (69.27 +/- 12.89 mg . h/liter). The calculated mean maximum concentration in saliva just after swallowing of the suspension was 97.99 +/- 6.12 mg/liter. The peak fluconazole concentration in saliva after the ingestion of the capsules was 3.55 +/- 0.40 mg/liter. The fluconazole oral suspension and capsules resulted in comparable concentrations and AUCs in plasma. Thus, because of a higher local level of drug exposure in terms of both higher peak concentrations in saliva and a higher salivary AUC, the fluconazole oral suspension has theoretical advantages over the capsule formulation in the treatment of oropharyngeal candidiases.