Toxoplasmic encephalitis and primary lymphoma of the brain--the shift in epidemiology: a case series and review of the literature.

With the advent of HAART, there has been a decline in the incidence of AIDS-defining illnesses. Despite this decline, we increasingly see patients who present with AIDS-defining illnesses similar to those seen during the early days of the HIV epidemic because patients are having difficulty in tolerating or adhering to their HAART regimens. In general, patients today are different: some are receiving prophylaxis to prevent HIV-related infections and many have experienced a more prolonged duration of immunosuppression resulting from intermittent use of HAART. We present 4 patients with neurologic symptoms and focal brain lesions and review and compare the diagnosis and treatment of toxoplasmic encephalitis with that of primary CNS lymphoma.

Effects of grapefruit juice on pharmacokinetic exposure to indinavir in HIV-positive subjects.

The objective of this study was to determine the effects of double-strength grapefruit juice on gastric pH and systemic bioavailability of indinavir in HIV-infected subjects receiving indinavir. Fourteen HIV-infected subjects took 800 mg of indinavir with 6 ounces (180 ml) of water or double-strength grapefruit juice. Gastric pH was measured and blood samples were collected for 5 hours after indinavir dosing. Grapefruit juice increased the mean gastric pH (from 1.39 +/- 0.4 to 3.20 +/- 0.3; p < 0.05) and slightly delayed the absorption of indinavir (tmax increased from 1.12 +/- 0.8 h to 1.56 +/- 0.6 h; p < 0.05). However, there were no significant differences in indinavir exposure. Cmax was 16.7 +/- 7.3 microM with water versus 13.9 +/- 4.2 microM with grapefruit juice (p = NS), and AUC0-8 was 37.5 +/- 19 with water versus 36.9 +/- 15 with grapefruit juice (p = NS). The authors concluded that concomitant administration of grapefruit juice increases gastric pH and delays indinavir absorption but does not uniformly affect the systemic bioavailability of indinavir in HIV-infected subjects.

Women's health. The role of gender in HIV progression.

Recent studies have examined the experience of women and the potential for gender differences with respect to HIV progression and the acceptance, tolerance, adherence, and response regarding HAART. Differences in CD4 cell count and viral load have not been reported in all studies. For any given CD4 cell count, women may be at a higher risk of HIV progression. Women appear to have an increased risk of progression to AIDS compared with men with the same viral load. They have lower initial viral loads than men in early-stage disease, but these catch up in advanced-stage disease. Because of depression and other psychological factors, women may be in greater need of supportive services, and this can affect the success of antiretroviral therapy. Women also have an increased risk of adverse drug reactions from HAART. Gender should be considered when prescribing therapy.

If taken 1 hour before indinavir (IDV), didanosine does not affect IDV exposure, despite persistent buffering effects.

Concurrent administration of indinavir and didanosine significantly reduces the level of exposure to indinavir, but it is unclear how soon after didanosine administration indinavir may be given safely. We compared indinavir pharmacokinetics and gastric pH in 12 human immunodeficiency virus-positive patients by use of 800 mg of indinavir alone versus 800 mg of indinavir administered 1 h after didanosine administration. Median gastric pH was significantly higher when indinavir was taken after didanosine administration; however, no significant difference in the maximum concentration in plasma or the area under the concentration-time curve from time zero to 8 h was observed. Indinavir may be taken with a light meal 1 h following the administration of 400 mg of didanosine.

Paromomycin: no more effective than placebo for treatment of cryptosporidiosis in patients with advanced human immunodeficiency virus infection. AIDS Clinical Trial Group.

To evaluate the efficacy of paromomycin for the treatment of symptomatic cryptosporidial enteritis in human immunodeficiency virus-infected adults, we conducted a prospective, randomized, double-blind, placebo-controlled trial before the widespread introduction of highly active antiretroviral therapy (HAART). Seven units under the auspices of the AIDS Clinical Trials Group enrolled 35 adults with CD4 cell counts of < or = 150/mm(3). Initially, 17 patients received paromomycin (500 mg 4 times daily) and 18 received matching placebo for 21 days. Then all patients received paromomycin (500 mg q.i.d.) for an additional 21 days. Clinical definitions of response were measured by an average number of bowel movements per day in association with concurrent need for antidiarrheal agents that was lower than that before study entry. There was no treatment response during the placebo-controlled phase of the study according to protocol-defined criteria (P=.88). Three paromomycin recipients (17.6%) versus 2 placebo recipients (14.3%) responded completely. Rates of combined partial and complete responses in the paromomycin arm (8 out of 17, 47.1%) and the placebo arm (5 out of 14, 35.7%) of the study were also similar (P=.72). The clinical course of cryptosporidiosis was quite variable. Paromomycin was not shown to be more effective than placebo for the treatment of symptomatic cryptosporidial enteritis. However, inadequate statistical power prevents definitive rejection of the usefulness of paromomycin as therapy for this infection.

Cocaine differentially modulates chemokine production by mononuclear cells from normal donors and human immunodeficiency virus type 1-infected patients.

Earlier studies have supported a significant role for cocaine in the susceptibility to and the progression of human immunodeficiency virus type 1 (HIV-1) infection. Recently, several unique HIV-1 entry coreceptors (e.g., CCR5 and CCR3) and a trio of HIV-1-specific suppressor chemokines, namely, RANTES (regulated-upon-activation T expressed and secreted), macrophage inflammatory protein 1alpha (MIP-1alpha) and MIP-1beta, were identified. Although cocaine has been linked to the immunopathogenesis of HIV-1 infection, the corresponding cellular and molecular mechanism(s) have not been well defined. We hypothesize that cocaine mediates these pathologic effects through the downregulation of HIV-1-suppressing chemokines and/or upregulating HIV-1 entry coreceptors in HIV-1-infected subjects, resulting in disease progression to AIDS. Our results show that cocaine selectively downregulates endogenous MIP-1beta secretion by normal peripheral blood mononuclear cells (PBMC), while cocaine did not affect the MIP-1beta production by PBMC from AIDS patients. Cocaine also selectively suppresses lipopolysaccharide-induced MIP-1beta production by PBMC from HIV-infected patients. Further, cocaine significantly downregulates endogenous MIP-1beta gene expression, while it upregulates HIV-1 entry coreceptor CCR5 by normal PBMC. These studies suggests a role for cocaine as a cofactor in the pathogenesis of HIV infection and support the premise that cocaine increases susceptibility to and progression of HIV-1 infection by inhibiting the synthesis of HIV-1 protective chemokines and/or upregulating the HIV-1 entry coreceptor, CCR5.

Impact of human immunodeficiency virus type-1-associated cognitive dysfunction on activities of daily living and quality of life.

We examined the impact of neuropsychological (NP) impairment on activities of daily living (ADLs) and quality of life in human immunodeficiency virus type-1 (HIV-1)-infected persons of low socioeconomic status (SES). Thirty-nine patients were stratified into one of three groups: cognitively normal (n = 13), mild cognitive impairment (n = 15), and moderate/severe impairment (n = 11). Quality of life was assessed with the Sickness Impact Profile and ADLs were evaluated via structured interview performed in the patient's residence. While there were no significant differences across groups on disease stage, drug use, depression, or estimated premorbid IQ, cognitively impaired patients were more likely to be unemployed and fail social planning and medication management tasks. Our study confirms a previously reported association between NP impairment and unemployment among HIV-1-infected patients. The data also extend this relationship to a low-SES sample with a high base rate of unemployment, and to instrumental activities of daily living other than work.

Natural history of intestinal microsporidiosis among patients infected with human immunodeficiency virus.

A chart review of 73 human immunodeficiency virus (HIV)-infected patients with enteric microsporidiosis was conducted to define the natural history of microsporidiosis. A substantial proportion of patients remained symptomatic after 6 months (54.8% with persistent diarrhea and 51.2% with weight loss). Predictors for persistent diarrhea included high HIV RNA viral load and no initiation of protease inhibitor therapy.

Prevention of disseminated Mycobacterium avium complex infection with reduced dose clarithromycin in patients with advanced HIV disease.

OBJECTIVE: To evaluate the ability of once daily reduced dose clarithromycin to prevent disseminated Mycobacterium avium complex (dMAC) infection in patients with advanced HIV disease. DESIGN: Non-randomized, retrospective study. SETTING: Outpatient clinic of an urban university-affiliated municipal hospital. PATIENTS: A group of 192 HIV-infected patients with a CD4 count < 100 x 10(6) cells/l who were followed for at least 90 days during a 6-year period (1991-1996) before the use of protease inhibitors. INTERVENTIONS: Clarithromycin 500 mg orally once daily (n = 84), rifabutin 300 mg orally once daily (n = 47) or no prophylaxis (n = 61). MAIN OUTCOME MEASURES: Positive blood culture for M. avium complex (MAC), time to development of dMAC, and time to death. RESULTS: When compared with no prophylaxis or rifabutin, the incidence of dMAC and time to development of dMAC were improved among those patients receiving clarithromycin (P < 0.001). Prolonged survival was associated with both clarithromycin and rifabutin use when compared with no prophylaxis (P < 0.002). In patients who failed prophylaxis, resistance to clarithromycin and rifabutin was observed. CONCLUSIONS: In the era prior to protease inhibitor use, once daily clarithromycin at a dose of 500 mg was associated with a reduction in the incidence of dMAC, appeared to be superior to rifabutin, and was associated with prolonged survival in patients with advanced HIV disease.

Comparison of a neural network approach with five traditional methods for predicting creatinine clearance in patients with human immunodeficiency virus infection.

STUDY OBJECTIVE: To compare the results of an artificial neural network approach with those of five published creatinine clearance (Cl(cr)) prediction equations and with the measured (true) Cl(cr) in patients infected with the human immunodeficiency virus (HIV). DESIGN: Six-month prospective study. SETTINGS: Two university medical centers. PATIENTS: Sixty-five HIV-infected patients: 18 relatively healthy outpatients and 47 inpatients. INTERVENTIONS: All subjects had urine collected for 24 hours to determine Cl(cr). MEASUREMENTS AND MAIN RESULTS: The 16 input variables were age, ideal body weight, actual body weight, body surface area, height, and the following blood chemistries: sodium, potassium, aspartate aminotransferase, alanine aminotransferase, red blood cell count, platelet count, white blood cell count, glucose, serum creatinine, blood urea nitrogen, and albumin. The only output variable was Cl(cr). A training set of 55 subjects was used to develop the relationship between input variables and the output variable. The trained neural network was then used to predict Cl(cr) of a validation set of 10 subjects. Mean differences between predicted Cl(cr) and actual Cl(cr) (bias) were 4.1, 28.7, 29.4, 26.0, 31.8, and 55.8 ml/min/1.73 m2 for the artificial neural network, Cockcroft and Gault, Jelliffe 1, Jelliffe 2, Mawer et al, and Hull et al methods, respectively. CONCLUSION: The accuracy of predicting Cl(cr) in subjects with HIV infection by the artificial neural network is superior to that of the five equations that are currently used in clinical settings.

Previous infection with Helicobacter pylori is the primary determinant of spontaneous gastric hypoacidity in human immunodeficiency virus-infected outpatients.

To investigate the incidence and demographics of gastric hypoacidity among persons infected with human immunodeficiency virus (HIV), 146 asymptomatic subjects were evaluated with use of a radiotelemetry device (Heidelberg capsule). Gastric hypoacidity (minimum gastric pH of > or = 3) occurred in 24 subjects (17%). Demographic characteristics, CD4 cell counts, and Helicobacter pylori serological status were evaluated for an association with gastric pH. Subjects with hypoacidity were more likely to have positive H. pylori serology than were subjects without hypoacidity (15 of 24 vs. 23 of 74, respectively; P = .004). Multivariate analysis indicated that a positive H. pylori serology was the most significant predictor of hypoacidity, accounting for an increase in gastric pH of 39%. A history of injection drug use, heterosexual transmission of HIV, and male gender were also associated with an elevated gastric pH. CD4 cell counts did not contribute to predictions of gastric pH. A history of H. pylori infection is relatively common in HIV-positive black and Hispanic populations and is a predictor of gastric pH.

Relationship between didanosine exposure and surrogate marker response in human immunodeficiency virus-infected outpatients.

We used information available from routine clinic visits to characterize the pharmacokinetics of didanosine in 82 human immunodeficiency virus-infected patients. A total of 271 blood samples were collected for the measurement of didanosine concentrations in plasma (mean +/- standard deviation [SD], 3.30 +/- 2.21 samples/patient). Bayesian estimates of didanosine oral clearance (CL[oral]) were obtained for these patients by the POSTHOC option within the NONMEM software package. Population priors from a previous NONMEM analysis of didanosine pharmacokinetics were used. The mean +/- SD CL(oral) was 132 +/- 27.7 liters/h, which agrees reasonably well with estimates obtained from previous pharmacokinetic studies of didanosine. Estimates of individual didanosine exposure were then used to consider potential relationships between drug exposure and surrogate marker response over a 6-month period. No correlations were found between the didanosine area under the concentration-time curve from 0 to 6 months and the absolute CD4 cell count (r = 0.305; 0.1 < P < 0.2), weight response (r = 0.0857; P > 0.4), or percentage of CD4 lymphocytes (r = 0.0559; P > 0.4). Future efforts to characterize didanosine exposure in outpatients by random sampling methods should involve more directed efforts to limit residual variability in the data.

Zalcitabine population pharmacokinetics: application of radioimmunoassay.

Zalcitabine population pharmacokinetics were evaluated in 44 human immunodeficiency virus-infected patients (39 males and 5 females) in our immunodeficiency clinic. Eighty-one blood samples were collected during routine clinic visits for the measurement of plasma zalcitabine concentrations by radioimmunoassay (1.84+/-1.24 samples/patient; range, 1 to 6 samples/patient). These data, along with dosing information, age (38.6+/-7.13 years), sex, weight (79.1+/-15.0 kg), and estimated creatinine clearance (89.1+/-21.5 ml/min), were entered into NONMEM to obtain population estimates for zalcitabine pharmacokinetic parameters. The standard curve of the radioimmunoassay ranged from 0.5 to 50.0 ng/ml. The observed concentrations of zalcitabine in plasma ranged from 2.01 to 8.57 ng/ml following the administration of doses of either 0.375 or 0.75 mg. A one-compartment model best fit the data. The addition of patient covariates did not improve the basic fit of the model to the data. Oral clearance was determined to be 14.8 liters/h (0.19 liter/h/kg; coefficient of variation [CV] = 23.8%), while the volume of distribution was estimated to be 87.6 liters (1.18 liters/kg; CV = 54.0%). We were also able to obtain individual estimates of oral clearance (range, 8.05 to 19.8 liters/h; 0.11 to 0.30 liter/h/kg) and volume of distribution (range, 49.2 to 161 liters; 0.43 to 1.92 liters/kg) of zalcitabine in these patients with the POSTHOC option in NONMEM. Our value for oral clearance agrees well with other estimates of oral clearance from traditional pharmacokinetic studies of zalcitabine and suggests that population methods may be a reasonable alternative to these traditional approaches for obtaining information on the disposition of zalcitabine.

Randomized trial of itraconazole oral solution for oropharyngeal candidiasis in HIV/AIDS patients.

PURPOSE: Oropharyngeal candidasis (thrush) is the most common opportunistic infection in individuals who are positive for the human immunodeficiency virus (HIV) and those who have progressed to AIDS. Itraconazole has a broad in vitro spectrum of activity, including a wide variety of Candida species. Our study determined the relative efficacy of a new oral solution formulation of itraconazole and fluconazole tablets in the treatment of oropharyngeal candidiasis. PATIENTS AND METHODS: This was a prospective randomized, third-party-blind, multicenter trial conducted at 12 centers in the United States. One hundred seventy-nine HIV-positive patients with mycologically documented oropharyngeal candidiasis were treated with itraconazole oral solution 200 mg/ day for 7 or 14 days, or fluconazole tablets 100 mg/day for 14 days. Severity of disease was scored clinically before treatment and at clinical evaluations on days 3, 7, 14, 21, 35, and 42. Semi-quantitative cultures of mouth washings were also obtained on these days. RESULTS: Both 14-day and 7-day regimens of itraconazole oral solution were equivalent to fluconazole for most efficacy parameters. The clinical response rate was 97% after 14 days of itraconazole and 87% after 14 days of fluconazole. Itraconazole oral solution given for 7 days was also equivalent to fluconazole treatment for 14 days. Approximately one half of patients in all three groups relapsed by 1 month after completion of treatment. There were few adverse reactions to either drug. CONCLUSION: Itraconazole oral solution is well tolerated and offers an alternative at least as effective as fluconazole in the treatment of oropharyngeal candidiasis.

Effects of spontaneous gastric hypoacidity on the pharmacokinetics of zidovudine and didanosine.

STUDY OBJECTIVE: To determine the effect of spontaneous gastric hypoacidity on the pharmacokinetics of zidovudine and didanosine in subjects infected with the human immunodeficiency virus (HIV). DESIGN: Controlled, open-label, single-dose, pharmacokinetic study. SUBJECTS: Thirty-two asymptomatic HIV-infected subjects. INTERVENTIONS: Gastric pH studies were conducted in all 32 subjects, and 20 of these subjects (8 women, 12 men) were enrolled into the pharmacokinetic study. They were stratified into two groups according to fasting gastric pH: those without and with gastric hypoacidity (minimum gastric pH < 3 and > or = 3, respectively). Gastric pH was measured using the Heidelberg pH monitoring system in all subjects before and during pharmacokinetic analysis of zidovudine 100 mg or didanosine 200 mg (given as two 100-mg tablets dissolved in 6 oz water). Plasma samples were collected over 8 hours after dosing. MEASUREMENTS AND MAIN RESULTS: Six (20%) of 30 subjects had a minimum gastric pH of 3 or above on at least two occasions, and the remaining 2 had variable gastric pH. Although gastric pH was unchanged during the administration of zidovudine, it increased to greater than 9 in 11 of 12 subjects with didanosine, regardless of baseline value. For both drugs, there were no statistically significant differences in peak plasma concentration (Cmax), time to reach peak plasma concentration (Tmax), elimination rate constant (ke), and area under the plasma concentration-time curve from time zero to infinity (AUC0-infinity) between subjects with and without gastric hypoacidity despite sufficient statistical power to detect a 56% difference in clearance for either drug (alpha 0.05, beta 0.1). CONCLUSION: Gastric hypoacidity occurs in approximately 20% of HIV-infected patients and does not appear to influence zidovudine or didanosine pharmacokinetics.

Comparison of measured and estimated creatinine clearance in patients with advanced HIV disease.

STUDY OBJECTIVE: To assess the accuracy of five creatinine clearance equations in predicting measured creatinine clearance in hospitalized patients with human immunodeficiency viral (HIV) infection. DESIGN: Prospective evaluation over a 6-month period. SETTING: Erie County Medical Center, a 550-bed teaching institution. PATIENTS: Forty-seven HIV-positive patients (39 men, 8 women) who were admitted for a variety of HIV-related illnesses and judged clinically to have stable renal function. Of the 47 original patients, 44 were evaluable based on exclusion criteria. INTERVENTIONS: Serum creatinine and 24-hour measured creatinine clearance were performed in each patient. MEASUREMENTS AND MAIN RESULTS: The estimated creatinine clearance from each of the equations (Cockcroft-Gault, two Jeliffe equations, Mawer et al, and Hull et al) was compared with the measured creatinine clearance. Statistical analysis of these comparisons was performed and all of the equations were found to overestimate the measured creatinine clearance (mean error 34-45%). CONCLUSIONS: Many HIV-infected patients have a decreased creatinine clearance despite a serum creatinine concentration within the normal range. Each of the equations overestimated the measured creatinine clearance.