Use of low-dose trimethoprim-sulfamethoxazole thrice weekly for primary and secondary prophylaxis of Pneumocystis carinii pneumonia in human immunodeficiency virus-infected patients

Too Much of a Good Thing: Defining Antimicrobial Therapeutic Targets to Minimize Toxicity

Antimicrobials are a common cause of drug toxicity. Understanding the relationship between systemic antimicrobial exposure and toxicity is necessary to enable providers to take a proactive approach to prevent undesired drug effects. When an exposure threshold has been defined that predicts drug toxicity, therapeutic drug monitoring (TDM) can be performed to assure drug exposure does not exceed the defined threshold. Although some antimicrobials have well-defined dose-dependent toxicities, many other exposure-toxicity relationships have either not been well-defined or, in some cases, not been evaluated at all. In this review, we examine the relationship between exposures and toxicities for antibiotic, antifungal, and antiviral agents. Furthermore, we classify these relationships into four categories: known association between drug exposure and toxicity such that clinical implementation of a specific exposure threshold associated with toxicity for TDM is supported (category 1), known association between drug exposure and toxicity but the specific exposure threshold associated with toxicity is undefined (category 2), association between drug exposure and toxicity has been suggested but relationship is poorly defined (category 3), and no known association between drug exposure and toxicity (category 4). Further work to define exposure-toxicity thresholds and integrate effective TDM strategies has the potential to minimize many of the observed antimicrobial toxicities.

High incidence of Pneumocystis jirovecii pneumonia in allogeneic hematopoietic cell transplant recipients in the modern era

BACKGROUND

International guidelines for Pneumocystis jirovecii pneumonia (PJP) prevention recommend prophylaxis for ≥6 months following allogeneic hematopoietic cell transplantation, and longer in patients with graft-versus-host disease (GVHD) or on immunosuppressive therapy (IST). These recommendations are based on cohorts of patients who did not routinely receive anti-thymocyte globulin (ATG) for GVHD prophylaxis.

METHODS

We performed a retrospective chart review of 649 patients, all of whom received ATG as part of GVHD prophylaxis.

RESULTS

The cumulative incidence of definite PJP was 3.52% at both 3 and 5 years (median follow up, 1648 days for survivors). PJP occurred in 13 non-GVHD patients between days 207 and 508, due in part to low CD4 T-cell counts (<200 CD4 T cells/µL). PJP occurred in eight GVHD patients between days 389 and 792, due in part to non-adherence to PJP prophylaxis guidelines (discontinuation of PJP prophylaxis at <3 months after discontinuation of IST). Breakthrough PJP infection was not observed in patients receiving prophylaxis with cotrimoxazole, dapsone or atovaquone, whereas three cases were observed with inhaled pentamidine.

DISCUSSION

In conclusion, for non-GVHD patients receiving ATG-containing GVHD prophylaxis, 6 months of PJP prophylaxis is inadequate, particularly if the CD4 T-cell count is <200 cells/µL or if there is a high incidence of PJP in the community. For patients with GVHD receiving ATG-containing GVHD prophylaxis, continuing PJP prophylaxis until ≥3 months post-discontinuation of IST is important. Cotrimoxazole, dapsone and atovaquone are preferred over inhaled pentamidine.

Treatment of Pneumocystis jirovecii pneumonia in HIV-infected patients: a review

INTRODUCTION

Pneumocystis pneumonia is a potentially life-threatening pulmonary infection that occurs in immunocompromised individuals and HIV-infected patients with a low CD4 cell count. Trimethoprim-sulfamethoxazole has been used as the first-line agent for treatment, but mutations within dihydropteroate synthase gene render potential resistance to sulfamide. Despite advances of combination antiretroviral therapy (cART), Pneumocystis pneumonia continues to occur in HIV-infected patients with late presentation for cART or virological and immunological failure after receiving cART. Areas covered: This review summarizes the diagnosis and first-line and alternative treatment and prophylaxis for Pneumocystis pneumonia in HIV-infected patients. Articles for this review were identified through searching PubMed. Search terms included: 'Pneumocystis pneumonia', 'Pneumocystis jirovecii pneumonia', 'Pneumocystis carinii pneumonia', 'trimethoprim-sulfamethoxazole', 'primaquine', 'trimetrexate', 'dapsone', 'pentamidine', 'atovaquone', 'echinocandins', 'human immunodeficiency virus infection', 'acquired immunodeficiency syndrome', 'resistance to sulfamide' and combinations of these terms. We limited the search to English language papers that were published between 1981 and March 2017. We screened all identified articles and cross-referenced studies from retrieved articles. Expert commentary: Trimethoprim-sulfamethoxazole will continue to be the first-line agent for Pneumocystis pneumonia given its cost, availability of both oral and parenteral formulations, and effectiveness or efficacy in both treatment and prophylaxis. Whether resistance due to mutations within dihydropteroate synthase gene compromises treatment effectiveness remains controversial. Continued search for effective alternatives with better safety profiles for Pneumocystis pneumonia is warranted.

Infectious diseases in allogeneic haematopoietic stem cell transplantation: prevention and prophylaxis strategy guidelines 2016

Infectious complications after allogeneic haematopoietic stem cell transplantation (allo-HCT) remain a clinical challenge. This is a guideline provided by the AGIHO (Infectious Diseases Working Group) of the DGHO (German Society for Hematology and Medical Oncology). A core group of experts prepared a preliminary guideline, which was discussed, reviewed, and approved by the entire working group. The guideline provides clinical recommendations for the preventive management including prophylactic treatment of viral, bacterial, parasitic, and fungal diseases. The guideline focuses on antimicrobial agents but includes recommendations on the use of vaccinations. This is the updated version of the AGHIO guideline in the field of allogeneic haematopoietic stem cell transplantation utilizing methods according to evidence-based medicine criteria.

Pneumocystis jirovecii Pneumonia

Pneumocystis jirovecii has gained attention during the last decade in the context of the AIDS epidemic and the increasing use of cytotoxic and immunosuppressive therapies. This article summarizes current knowledge on biology, pathophysiology, epidemiology, diagnosis, prevention, and treatment of pulmonary P jirovecii infection, with a particular focus on the evolving pathophysiology and epidemiology. Pneumocystis pneumonia still remains a severe opportunistic infection, associated with a high mortality rate.

Autoimmune inflammatory disorders, systemic corticosteroids and pneumocystis pneumonia: a strategy for prevention

Background

Pneumocystis pneumonia (PCP) is an increasing problem amongst patients on immunosuppression with autoimmune inflammatory disorders (AID). The disease presents acutely and its diagnosis requires bronchoalveolar lavage in most cases. Despite treatment with intravenous antibiotics, PCP carries a worse prognosis in AID patients than HIV positive patients. The overall incidence of PCP in patients with AID remains low, although patients with Wegener's granulomatosis are at particular risk.

Discussion

In adults with AID, the risk of PCP is related to treatment with systemic steroid, ill-defined individual variation in steroid sensitivity and CD4+ lymphocyte count. Rather than opting for PCP prophylaxis on the basis of disease or treatment with cyclophosphamide, we argue the case for carrying out CD4+ lymphocyte counts on selected patients as a means of identifying individuals who are most likely to benefit from PCP prophylaxis.

Summary

Corticosteroids, lymphopenia and a low CD4+ count in particular, have been identified as risk factors for the development of PCP in adults with AID. Trimethoprim-sulfamethoxazole (co-trimoxazole) is an effective prophylactic agent, but indications for its use remain ill-defined. Further prospective trials are required to validate our proposed prevention strategy.

Twice-weekly pyrimethamine-sulfadoxine effectively prevents Pneumocystis carinii pneumonia relapse and toxoplasmic encephalitis in patients with AIDS

OBJECTIVE

To evaluate the safety and efficacy of a fixed 25mg pyrimethamine--500mg sulfadoxine combination plus 15mg folinic acid given twice weekly for the prevention of relapses of Pneumocystis carinii pneumonia (PCP) and primary episodes of toxoplasmic encephalitis.

METHODS

Ninety-five HIV-infected patients with successfully treated PCP and without history of toxoplasmic encephalitis were enrolled between January 1990 and October 1995 in a single-arm open-label prospective study. No patient was receiving highly active antiretroviral treatment, including protease inhibitors or non-nucleoside reverse transcriptase inhibitors, while on study medication. Efficacy was analysed on an "as-treated" basis.

RESULTS

Five patients (5.3%) suffered a PCP relapse while on study medication, three of whom had been non-compliant. No relapse occurred in the first year. Probabilities of freedom from relapse were 0.96 after 24 months and 0.90 after 36 months. Of 69 patients positive for anti-toxoplasma IgG antibodies, one (1.5%) developed cerebral lesions compatible with toxoplasmic encephalitis after 50 months. Cutaneous allergic reactions were observed in 16 patients (16.8%) resulting in permanent discontinuation in six patients (6.3%). Two patients (2.1%) developed serious adverse reactions (Stevens-Johnson syndrome), both of whom had continued prophylaxis despite progressive hypersensitivity reactions.

CONCLUSIONS

The prophylactic regimen used is effective in preventing PCP relapses and toxoplasmic encephalitis. The regimen appears to be safe. Severe adverse events can likely be prevented by discontinuation of prophylaxis at the time allergic reactions are noted. Rechallenge frequently results in tolerance of the regimen. Efficacy and safety compare favourably with previously studied regimens. This simple prophylactic regimen may provide a convenient alternative for patients unable to tolerate approved regimens.

Comparison of high and low doses of trimethoprim-sulfamethoxazole for primary prevention of toxoplasmic encephalitis in human immunodeficiency virus-infected patients

To evaluate the influence of the dose of co-trimoxazole prophylaxis on the risk of toxoplasmosis in human immunodeficiency virus (HIV)-infected patients, we performed a nested case-control study of 32 patients with toxoplasmosis (case patients) and 64 patients without toxoplasmosis (control patients) who were matched by CD4 cell count and Toxoplasma gondii serostatus; these patients were from a cohort of 521 HIV-infected patients who underwent a diagnostic neuroimaging study between March 1993 and January 1997. Twenty-seven (84.4%) of 32 case patients and 33 (51.6%) of 64 control patients received low doses of co-trimoxazole, a finding associated with an adjusted odds ratio (OR) of 9.36 (95% confidence interval [CI], 2.05-42.75) and indicating 89% protective efficacy for high doses. Fifteen (46.9%) of 32 case patients and 16 (25%) of 64 control patients were exposed to rifampin (adjusted OR, 3.38; 95% CI, 1.08-10.61). These results indicate that high doses of co-trimoxazole appear to be more effective than low doses for lowering the risk of toxoplasmosis in HIV-infected patients and that rifampin therapy may reduce the efficacy of co-trimoxazole.

A controlled trial of dapsone versus pyrimethamine-sulfadoxine for primary prophylaxis of Pneumocystis carinii pneumonia and toxoplasmosis in patients with AIDS

Pneumocystis carinii pneumonia (PCP) is the most common opportunistic human immunodeficiency virus (HIV)-related infection, occurring in 85% of HIV infected patients without prophylaxis. Preventive treatment is required when CD4 cell count falls below 200 cells per cubic millimeter. Cotrimoxazole has been shown to be highly effective but alternative drug regimens are often necessary because of the frequent drug hypersensitivity exhibited by HIV infected patients. The aim of this prospective, open, randomized, one-site study, involving HIV-infected patients with a CD4 cell count below 200/mm3, or a percentage under 20%, randomly assigned to receive either dapsone 50 mg daily or Fansidar one tablet weekly, was to compare the efficacy and safety of these drugs in the primary prophylaxis of PCP. Both dapsone and Fansidar appear to be safe and effective alternative agents for the prevention of PCP. Their role in Toxoplasma gondii prophylaxis requires further evaluation.

Pneumocystis carinii

Improved understanding of Pneumocystis carinii, in particular the widespread use of chemoprophylaxis, has resulted in a declining incidence of infection in patients infected with HIV since the late 1980s. Despite these advances, P. carinii pneumonia continues to represent an important cause of pulmonary disease in HIV-seropositive individuals who do not receive chemoprophylaxis or when breakthrough episodes occur. This article reviews the history, biology, clinical manifestations, prognostic markers, therapy, and chemoprophylaxis of P. carinii pneumonia in HIV-seropositive patients.

Successful oral desensitization to trimethoprim-sulfamethoxazole in acquired immune deficiency syndrome

OBJECTIVE

To study the outcome of a modified oral desensitization protocol for trimethoprim-sulfamethoxazole in human immunodeficiency virus infected patients with Pneumocystis carinii pneumonia and acquired immune deficiency syndrome.

DESIGN

A prospective study.

SETTING

Tertiary care referral center.

PATIENTS

Thirteen human immunodeficiency virus infected patients with Pneumocystis carinii pneumonia and allergy to sulfonamides who failed alternative therapy.

INTERVENTION

Oral desensitization to trimethoprim-sulfamethoxazole.

MEASUREMENTS

Nature of allergic reactions, toxicity of alternate medications, indication as well as outcome of trimethoprim-sulfamethoxazole desensitization and routine laboratory determinations.

RESULTS

The most common reaction to trimethoprim-sulfamethoxazole was generalized, pruritic maculopapular rash (n = 10, 76.9%) followed by urticaria/angioedema in two patients (15.38%). Two patients had generalized pruritus without rash. All patients (n = 13) tolerated oral desensitization to trimethoprim-sulfamethoxazole without any adverse reactions including three patients who were critically ill and on mechanical ventilation. Thus the success rate of our protocol was 100%. No patient had received antihistamines prior to or during the protocol. Four patients (5, 6, 7, and 9) were receiving prednisone for severe Pneumocystis carinii pneumonia. Total followup has ranged from 4 to 84 weeks. Two patients died during followup due to causes unrelated to desensitization. All other patients are tolerating trimethoprim-sulfamethoxazole without any allergic reactions.

CONCLUSIONS

Oral desensitization to trimethoprim-sulfamethoxazole, as per this protocol is safe, in that there were no systemic or cutaneous reactions during desensitization as well as followup. It is well tolerated in all patients, including the three critically ill patients. As judged by the outcome and ability to tolerate trimethoprim-sulfamethoxazole after desensitization, the procedure is successful in all patients in this study. Equipped with this protocol one can evaluate possible mechanisms of desensitization such as oral tolerance or mediator depletion in a controlled fashion.

Pharmacoeconomics of Pneumocystis carinii pneumonia in HIV-infected and HIV-noninfected patients

Despite the proven effectiveness of Pneumocystis carinii pneumonia (PCP) prophylaxis in both HIV-infected and HIV-noninfected patients, PCP remains an important cause of serious pulmonary infection. Because PCP is a frequent event requiring inpatient admission at our institution, we conducted a study to define the pharmacoeconomics of this infection and the incidence of adverse events associated with anti-PCP therapy. In a retrospective review, 133 patients (101 HIV-positive, 32 HIV-negative) with documented PCP were identified. Significant differences in age, initial arterial oxygen tension (paO2), intensive care unit admission and mortality were evident between HIV-infected and non-HIV-infected patients; however, there were no differences in the duration of hospitalisation or the duration of anti-PCP therapy. The incidence of biochemical abnormalities was similar between the groups. Leucopenia occurred at an incidence of 52 and 31%, while thrombocytopenia occurred at a rate of 7 and 44%, in HIV-positive and HIV-negative patients, respectively. Drug toxicity or treatment failure necessitated a change of therapy in 43% of HIV-positive and 59% of HIV-negative patients. PCP treatment cost, pharmacy cost, hospital cost and net loss (i.e. the difference between hospital cost and reimbursement) were all significantly greater in HIV-negative than in HIV-positive patients. The duration of anti-PCP therapy and the hospital cost for cotrimoxazole (trimethoprim-sulfamethoxazole)- and pentamidine-treated patients were similar, although the treatment cost and pharmacy cost were statistically different in favour of cotrimoxazole. Overall, cotrimoxazole is an inexpensive treatment option. However, the high incidence of adverse events attributed to this agent often necessitates a change to a more costly therapy.

Primary care of the HIV patient: standard practice and new developments in the era of managed care

It is easy when taking care of the patient with AIDS to lose sight of the whole person and become focused on the details of micromanagement, distracted by the array of new therapies, and overwhelmed by the financial risks of the disease. It is therefore critical that a healing and respectful relationship is developed with patients and they are engaged in the decisions regarding their care. Physicians must also continue the search for new therapies and struggle to ensure that patients have access to state-of-the-art treatment. In this, the primary care physician plays a critical role, through identifying study centers, becoming an investigator in expanded access programs, and using referrals to clinical trials to provide new therapies to patients and improve understanding of HIV treatment. Finally, quality of life must be at the forefront of physicians' medical conscience. Ultimately, the physician must know when the best treatment he of she can offer is the assurance of a dignified and comfortable death.

Risks and benefits of aerosolized pentamidine and cotrimoxazole in primary prophylaxis of Pneumocystis carinii pneumonia in HIV-1-infected patients: a two-year Italian multicentric randomized controlled trial. The Italian PCP Study Group

We randomized 220 HIV-1-infected subjects to receive aerosolized pentamidine (300 mg/4 weeks) or orally trimethoprim-sulfamethoxazole (320-1600 mg/day) for primary prophylaxis of Pneumocystis carinii pneumonia (PCP), and evaluated PCP and toxoplasmic encephalitis (TE) occurrence and survival. Patients developing toxicity switched to the other regimen. Analysis was on intention-to-treat. At 1 year of study, we observed in the pentamidine group a non-significant excess of PCP (4 vs. 1) and TE (7 vs. 3), and a significant increased death rate (15 vs. 2). After 2 years, no significant differences were observed: adjusted RR estimates for pentamidine vs. cotrimoxazole were 1.20 (95% CI, 0.33-4.37) for PCP (6 cases vs. 5), 1.23 (95% CI, 0.46-3.29) for TE (10 vs. 8) and 1.52 (95% CI, 0.83-2.79) for death (30 vs. 18). Crossovers were more frequent in the cotrimoxazole group (41 vs. 4, P < 0.001). Aerosolized pentamidine and cotrimoxazole were equally effective in preventing PCP, and no major differences were observed in TE occurrence and survival after 2 years follow-up.

The tolerance for zidovudine plus thrice weekly or daily trimethoprim-sulfamethoxazole with and without leucovorin for primary prophylaxis in advanced HIV disease. California Collaborative Treatment Group

PURPOSE

Trimethoprim-sulfamethoxazole (TMP/SMX) is the preferred agent for prophylaxis of Pneumocystis carinii pneumonia (PCP) in patients with HIV infection, but frequent adverse events limit its usefulness. Intermittent dosing and supplementation with leucovorin have been tried in attempts to improve tolerance. We evaluated these strategies in persons with advanced HIV disease.

METHOD

One hundred seven patients were enrolled. All had HIV infection, < 200 CD4+ lymphocytes per mm3, and no history of PCP. Fifty-two were randomized to TMP/SMX twice daily (BID); of these, 26 were randomized to leucovorin with each dose. Fifty-five patients were randomized to TMP/SMX (BID) 3 times per week; of these, 27 were randomized to leucovorin with each dose. All patients took zidovudine concurrently.

RESULTS

The 24-week risk of discontinuation due to protocol-defined limiting toxicity was 24% with thrice-weekly TMP/SMX versus 42% with daily TMP/SMX (risk ratio 0.4; 95% CI 0.2 to 1.0). The risks of discontinuation for any reason were 41% and 59% (risk ratio 0.4; 95% CI 0.2 to 0.8). Clinical toxicity, such as headache and gastrointestinal distress, accounted for the observed difference in tolerance between dosing regimens. The 24-week risk of discontinuation due to protocol-defined toxicity was 33% in both the leucovorin and non-leucovorin groups (risk ratio 1.1; 95% CI 0.5 to 2.5). The risks of discontinuation for any reason were 53% and 47% (risk ratio 0.8; 95% CI 0.3 to 1.7).

CONCLUSION

Intermittent therapy with TMP/SMX BID thrice weekly is better tolerated than daily BID therapy. Leucovorin use does not improve tolerance for chronic TMP/SMX dosing in AIDS, even among patients taking tablets daily.

Prevention of Pneumocystis carinii pneumonia and of cerebral toxoplasmosis by roxithromycin in HIV-infected patients

The prevention of cerebral toxoplasmosis and of Pneumocystis carinii pneumonia is an essential objective in the management of patients infected with HIV. Given that roxithromycin is active in vitro against Toxoplasma gondii and that in 1989 Dolermann reported the effective treatment of P. carinii respiratory infections with erythromycin, a randomized pilot study was undertaken in 52 patients infected with HIV. Patients were treated with either: a monthly dose of pentamidine aerosol (300 mg); roxithromycin once a week (300 mg t.i.d.); or a combination of pentamidine aerosol and roxithromycin. Intention to treat analysis was applied to these 52 patients, all of whom received at least one treatment dose. Five out of 18 patients treated with pentamidine aerosol, 1/17 patients treated with pentamidine aerosol + roxithromycin and none of the 17 patients treated with roxithromycin developed cerebral toxoplasmosis (p = 0.038). P. carinii pneumonia was diagnosed in one patient in the pentamidine aerosol-treated group, in one patient treated with roxithromycin and in none of the patients treated with pentamidine aerosol + roxithromycin (non-significant difference). Four cases of Mycobacterium tuberculosis and Mycobacterium avium-intracellulare infection were seen in the pentamidine aerosol-treated group (p = 0.028) and none in the roxithromycin groups. Adverse events leading to the discontinuation of treatment occurred in 5/34 (14.7%) patients treated with roxithromycin. Nausea, abdominal pain and raised transaminases occurred in four patients and a skin allergy in the final patient. Roxithromycin appears to be effective in the prevention of pulmonary pneumocystis infection and of cerebral toxoplasmosis in HIV-infected patients. However, these results require confirmation in a larger study.

Levels of dapsone and pyrimethamine in serum during once-weekly dosing for prophylaxis of Pneumocystis carinii pneumonia and toxoplasmic encephalitis

Concentrations of dapsone, monoacetyldapsone, and pyrimethamine were determined in 36 serum samples from human immunodeficiency virus-infected patients on prophylaxis with once-weekly administration of dapsone-pyrimethamine (200 mg of dapsone-75 mg of pyrimethamine). During day 1 after ingestion, median levels of 1,038 ng of dapsone per ml and 356 ng of pyrimethamine per ml were found. During days 6 to 7, the dapsone level fell to < 20 ng/ml in five of nine serum samples, but the pyrimethamine level remained elevated (125 ng/ml). Concurrent, but separately ingested, didanosine administration did not seem to decrease the drug concentrations.

Pneumocystis carinii pneumonia in cancer patients

Concern has been arisen about the recently reported increasing incidence of PCP in patients with cancer and the potential transmissibility of this infection. Whether or not there is an increase in the incidence of P. carinii infections, PCP should be considered in the differential diagnosis of pulmonary infiltrates in bone marrow transplant recipients, in patients with hematologic neoplasms and in patients with primary or metastatic brain neoplasms. Intensity of immunosuppression plays a crucial role, especially long-term (> 2 months) corticosteroid treatment. PCP is usually manifested clinically during augmentation or during tapering of corticosteroid dose. Thus, if the chest radiograph of a high-risk patient shows diffuse infiltrates, bronchoscopy and bronchoalveolar lavage should be done immediately. Treatment options are the same as for the AIDS population, except that TMP-SMX is tolerated better in non-AIDS patients. The role of supportive care, including mechanical ventilation in such patients should not be underestimated. Oral therapy with dapsone-trimethoprim or with atovaquone, can be as effective as conventional therapy in mild disease, permitting treatment on an outpatient basis. PCP is often preventable and our understanding has improved about when prophylaxis should be initiated. In the future, the emergence of new technologies for diagnosis and of new agents for treatment and prophylaxis, will bring us closer to the goal of controlling this serious infection.

A randomized comparison of once-monthly or twice-monthly high-dose aerosolized pentamidine prophylaxis

RESULTS

Ten of the 146 (7 percent) evaluable subjects developed PCP during the year study period, and there was no difference in the efficacy of the two regimens. Among patients receiving secondary prophylaxis, the attack rate of PCP at 1 year was 11 percent. This compares favorably with a 1-year attack rate of 19 percent in similar patients receiving standard dose (300 mg) prophylaxis and suggests, but does not prove, a dose-response effect. Concentrations of pentamidine in BAL fluid were not significantly different among the three lobes of the lung. Intrapulmonary pentamidine did not accumulate during the year of study. Aerosolized pentamidine was associated with a marginal but statistically significant increase in the residual volume, decreased flow rates, and increased airway reactivity.

OBJECTIVE

The optimal regimen of aerosolized pentamidine in unknown. Published data suggest that there is a dose-response effect and that the occurrence of Pneumocystis carinii pneumonia (PCP) has been associated with prolongation of the interval between doses. The purpose of this study was to compare the efficacy, pharmacokinetics, and physiologic effects of two high-dose regimens of aerosolized pentamidine prophylaxis.

DESIGN

Prospective, randomized study of 300 mg twice monthly vs 600 mg once monthly during a 1-year observation period. Pentamidine concentrations in plasma and bronchoalveolar lavage (BAL) fluid were measured and serial pulmonary function was measured.

SETTING

A large teaching hospital in San Francisco.

PATIENTS

One hundred fifty-one adult (age > 18 years) men with human immunodeficiency virus infection. Of 146 evaluable patients, prophylaxis was primary (no prior PCP) in 108 (75 percent) and secondary (one prior episode of PCP) in 38 (25 percent).

MEASUREMENTS

Date and diagnosis of PCP, occurrence of drug toxicity, pulmonary function testing, and concentrations of pentamidine in BAL and plasma.

CONCLUSIONS

The data suggest, but do not prove, that a dose-response effect has been demonstrated, and that high-dose aerosolized pentamidine may further reduce the attack rate of PCP. These preliminary observations should be confirmed in a double-blind trial comparing 300 mg with 600 mg administered once monthly. The clinical relevance of the adverse pulmonary effects is unclear and requires further investigation.

Multiple-dose pharmacokinetics of 12 milligrams of trimethoprim and 60 milligrams of sulfamethoxazole per kilogram of body weight per day in healthy volunteers

The disposition of 12 mg of trimethoprim and 60 mg of sulfamethoxazole per kg of body weight in six healthy male volunteers is described. The daily dose was evenly divided and administered orally every 6 h for 13 consecutive doses. Individual drug components were assayed by high-performance liquid chromatography. Steady-state concentrations in serum for trimethoprim and sulfamethoxazole were within the purported therapeutic ranges for treating Pneumocystis carinii pneumonia. Co-trimoxazole was well tolerated, and no subject withdrew from the study because of toxicity. Comparison of the pharmacokinetic parameters in this study with those of our previous findings indicates that the elimination of trimethoprim-sulfamethoxazole follows a first-order process within the dose ranges assessed. Administration of 15- to 20-mg/kg trimethoprim and 75- to 100-mg/kg sulfamethoxazole in four evenly divided doses for the first 24 h followed by 12 and 60 mg/kg/day, respectively, for the remainder of therapy rapidly attains concentrations in serum within the proposed P. carinii pneumonia therapeutic range. Clinical trials are indicated to evaluate this dosing scheme, which may decrease exposure to potentially excessive concentrations of trimethoprim and sulfamethoxazole.

Human immunodeficiency virus infection in pregnancy

Human immunodeficiency virus (HIV) infection in women is an increasing problem. World wide, at least 25% of all infections occur in adolescent or adult women, most of whom are of child-bearing age. The commonest modes of acquisition of HIV infection are sexual contact with an HIV-infected male and sharing needles during injecting drug use. Vertical transmission is the major route of HIV infection in infants and children and can occur in utero, intrapartum, through exposure to infected blood or secretions, or post partum, via breast milk. HIV infection has not been demonstrated to affect fertility, or to influence the outcome of pregnancy unless there is evidence of significant immune dysfunction, with CD4 counts below 400/mm3. Though data are limited, pregnancy does not appear to affect the course of HIV infection. Low CD4 counts predispose women to the opportunistic infectious complications of HIV. Pathogens include Candida sp., Mycobacterium tuberculosis, Pneumocystis carinii, Toxoplasma gondii, Cryptococcus neoformans and Cryptosporidium. These pathogens require early recognition and diagnosis if optimal treatment and outcome are to be attained. Treatment with zidovudine and prophylaxis against Pneumocystis carinii are appropriate when CD4 counts are less than 200/mm3, though the safety of zidovudine in early pregnancy is not known. Similarly it is not known whether zidovudine treatment of the mother prevents transmission of HIV infection to her baby. Caesarean section does not prevent peripartum transmission of HIV and should be undertaken only for other appropriate indications. The utility of antenatal screening for HIV depends upon the seroprevalence in the population. Such programmes must be supported by comprehensive clinical care as well as sensitive and non-judgemental counselling.

A controlled trial of aerosolized pentamidine or trimethoprim-sulfamethoxazole as primary prophylaxis against Pneumocystis carinii pneumonia in patients with human immunodeficiency virus infection. The Dutch AIDS Treatment Group

BACKGROUND

Primary prophylaxis against Pneumocystis carinii pneumonia (PCP) is recommended for patients with human immunodeficiency virus (HIV) infection if their CD4 cell counts are below 200 per cubic millimeter (0.2 x 10(9) per liter). Either aerosolized pentamidine or trimethoprim-sulfamethoxazole (co-trimoxazole) is commonly prescribed for prophylaxis, but the relative efficacy and toxicity of these agents are unknown.

METHODS

We conducted a multicenter trial involving 215 HIV-infected patients with no history of PCP but with CD4 cell counts below 200 per cubic millimeter. The patients were randomly assigned to one of three regimens: aerosolized pentamidine once a month, 480 mg of trimethoprim-sulfamethoxazole once a day (80 mg of trimethoprim and 400 mg of sulfamethoxazole), or 960 mg of trimethoprim-sulfamethoxazole once a day (160 mg and 800 mg, respectively). The cumulative incidence of PCP was estimated by Kaplan-Meier survival analysis.

RESULTS

After a mean follow-up of 264 days, 6 of the 71 patients in the pentamidine group had a confirmed first episode of PCP (11 percent), whereas none of the 142 patients in the two trimethoprim-sulfamethoxazole groups had PCP (P = 0.002). However, adverse events that required discontinuation of the medication were much more frequent in the trimethoprim-sulfamethoxazole groups (17 and 18 patients) than in the pentamidine group (2 patients). The adverse reactions occurred significantly sooner in the group given 960 mg of trimethoprim-sulfamethoxazole than in the group given 480 mg (mean time, 16 vs. 57 days; P = 0.02).

CONCLUSIONS

For patients with HIV infection, trimethoprim-sulfamethoxazole taken once a day is more effective as primary prophylaxis against PCP than aerosolized pentamidine administered once a month, although adverse drug reactions are more frequent with trimethoprim-sulfamethoxazole.

Low-dose trimethoprim-sulfamethoxazole alone and in association with zidovudine for prevention and treatment of murine Pneumocystis carinii pneumonia

Low-dose trimethoprim-sulfamethoxazole (TMP-SMX) alone was found to be as effective as low-dose TMP-SMX plus zidovudine and standard-dose TMP-SMX alone in preventing and treating Pneumocystis carinii pneumonia (PCP) in an immunosuppressed-rat model. Zidovudine alone had no preventive or curative effect on PCP. We conclude that the initially reported reduced incidence of PCP in human immunodeficiency virus-infected patients treated with zidovudine alone is not due to anti-P. carinii activity of zidovudine. Furthermore, the clinical efficacy of low-dose TMP-SMX for the prevention and treatment of PCP should be further investigated.