High frequency of potential phosphodiesterase type 5 inhibitor drug interactions in males with HIV infection and erectile dysfunction

OBJECTIVES

We sought to determine the prevalence of phosphodiesterase type 5 inhibitor (PDE-5) mediated drug-drug interactions (DDIs) in males with HIV infection receiving antiretroviral therapy (ART) and identify factors associated with PDE-5-mediated DDIs.

METHODS

Male US Military HIV Natural History Study participants diagnosed with erectile dysfunction (ED) and having a PDE-5 inhibitor and potentially-interacting ART co-dispensed within 30 days were included. DDIs were defined according to criteria found in published guidelines and drug information resources. The primary outcome of interest was overall PDE-5 inhibitor-mediated DDI prevalence and episode duration. A secondary logistic regression analysis was performed on those with and without DDIs to identify factors associated with initial DDI episode.

RESULTS

A total of 235 male participants with ED met inclusion criteria. The majority were White (50.6%) or African American (40.4%). Median age at medication co-dispensing (45 years), duration of HIV infection (14 years), and duration of ED (1 year) did not differ between the two groups (p>0.05 for all). PDE-5 inhibitors included sildenafil (n = 124), vardenafil (n = 99), and tadalafil (n = 14). ART regimens included RTV-boosted protease inhibitors (PIs) atazanavir (n = 83) or darunavir (n = 34), and COBI-boosted elvitegravir (n = 43). Potential DDIs occurred in 181 (77.0%) participants, of whom 122 (67.4%) had multiple DDI episodes. The median DDI duration was 8 (IQR 1-12) months. In multivariate analyses, non-statistically significant higher odds of DDIs were observed with RTV-boosted PIs or PI-based ART (OR 2.13, 95% CI 0.85-5.37) and in those with a diagnosis of major depressive disorder (OR 1.74, 95% CI 0.83-3.64).

CONCLUSIONS

PDE-5-mediated DDIs were observed in the majority of males with HIV infection on RTV- or COBI-boosted ART in our cohort. This study highlights the importance of assessing for DDIs among individuals on ART, especially those on boosted regimens.

602. Factors Associated With Erectile Dysfunction Diagnosis in HIV-Infected Individuals: A Case–Control Study

Background

Methods

Results

Conclusion

Disclosures

The Role of Cefepime in the Treatment of Extended-Spectrum Beta-Lactamase Infections

OBJECTIVE

To review the efficacy of cefepime for use in infections caused by extended-spectrum beta-lactamase (ESBL)-producing organisms.

DATA SOURCES

A PubMed literature search (May 2000 to June 2017) was performed using the keyword cefepime and the MeSH terms beta-lactamases, cephalosporinases, and Enterobacteriaceae infections.

STUDY SELECTION AND DATA EXTRACTION

All human, English language studies evaluating cefepime use for the treatment of ESBL-producing Escherichia coli and Klebsiella pneumoniae infections were included.

DATA SYNTHESIS

Studies assessing the use of cefepime for ESBL infections are few, and clinical studies are limited by design and sample size. The largest pharmacokinetic/pharmacodynamic study, a Monte Carlo simulation using data from the U.S. SENTRY antimicrobial surveillance program, evaluating cefepime use for infections due to ESBL-producing organisms found a 95% to 100% probability of target attainment with traditional cefepime dosing regimens. Most clinical studies found that patients treated with cefepime empirically and definitively had higher rates of mortality than those treated with carbapenems. However, in concordance with other studies reporting minimum inhibitory concentration (MIC) data, lower MICs were associated with lower mortality.

CONCLUSIONS

Cefepime should be avoided for empiric treatment of suspected ESBL infections and should only be considered for definitive treatment if the MIC ≤1 µg/mL. However, the site and severity of infection, local resistance patterns, and patient-specific risk factors should also help guide antimicrobial selection.

Intravenous Antibiotic and Antifungal Agent Pharmacokinetic-Pharmacodynamic Dosing in Adults with Severe Burn Injury

PURPOSE

Despite advances in the care of patients with severe burn injury, infection-related morbidity and mortality remain high and can potentially be reduced with antimicrobial dosing optimized for the infecting pathogen. However, anti-infective dose selection is difficult because of the highly abnormal physiologic features of burn patients, which can greatly affect the pharmacokinetic (PK) disposition of these agents. We review published PK data from burn patients and offer evidence-based dosing recommendations for antimicrobial agents in burn-injured patients.

METHODS

Because most infections occur at least 48 hours after initial burn injury and anti-infective therapy often lasts ≥10 days, we reviewed published data informing PK-pharmacodynamic (PD) dosing of anti-infectives administered during the second, hypermetabolic stage of burn injury, in those with >20% total body surface area burns, and in those with normal or augmented renal clearance (estimated creatinine clearance ≥130 mL/min). Analyses were performed using 10,000-patient Monte Carlo simulations, which uses PK variability observed in burn patients and MIC data to determine the probability of reaching predefined PK-PD targets. The probability of target attainment, defined as the likelihood that an anti-infective dosing regimen would achieve a specific PK-PD target at the single highest susceptible MIC, and the cumulative fraction of response, defined as the population probability of target attainment given a specific dose and a distribution of MICs, were calculated for each recommended anti-infective dosing regimen.

FINDINGS

Evidence-based doses were derived for burn-injured patients for 15 antibiotics and 2 antifungal agents. Published data were unavailable or insufficient for several agents important to the care of burn patients, including newer antifungal and antipseudomonal agents. Furthermore, available data suggest that antimicrobial PK properties in burned patients is highly variable. We recommend that, where possible, therapeutic drug monitoring be performed to optimize PK-PD parameter achievement in individual patients.

IMPLICATIONS

Given the high variability in PK disposition observed in burn patients, doses recommended in the package insert may not achieve PK-PD parameters associated with optimal infectious outcomes. Our study is limited by the necessity for fixed assumptions in depicting this highly variable patient population. New rapid-turnaround analytical technology is needed to expand the menu of antimicrobial agents for which therapeutic drug monitoring is available to guide dose modification within a clinically actionable time frame.

Micafungin in the treatment of invasive candidiasis and invasive aspergillosis

Micafungin is an echinocandin antifungal agent available for clinical use in Japan, Europe, and the United States. Through inhibition of β-1,3-glucan production, an essential component of the fungal cell wall, micafungin exhibits potent antifungal activity against key pathogenic fungi, including Candida and Aspergillus species, while contributing minimal toxicity to mammalian cells. This activity is maintained against polyene and azole-resistant isolates. Pharmacokinetic and pharmacodynamic studies have demonstrated linear kinetics both in adults and children with concentration-dependent activity observed both in vitro and in vivo. Dosage escalation studies have also demonstrated that doses much higher than those currently recommended may be administered without serious adverse effects. Clinically, micafungin has been shown to be efficacious for the treatment of invasive candidiasis and invasive aspergillosis. Furthermore, the clinical effectiveness of micafungin against these infections occurs without the drug interactions that occur with the azoles and the nephrotoxicity observed with amphotericin B formulations. This review will focus on the pharmacology, clinical microbiology, mechanisms of resistance, safety, and clinical efficacy of micafungin in the treatment of invasive candidiasis and invasive aspergillosis.