Drug interactions with itraconazole, fluconazole, and terbinafine and their management

Effectiveness and safety of oral terbinafine for dermatophyte distal subungual onychomycosis

INTRODUCTION

Terbinafine has been a cornerstone in dermatophyte infection treatment. Despite its global efficacy, the emergence of terbinafine resistance raises concerns, requiring ongoing vigilance.

AREAS COVERED

This paper focuses on evaluating the efficacy and safety of terbinafine in treating dermatophyte toenail infections. Continuous and pulse therapies, with a 24-week continuous regimen and a higher dosage of 500 mg/day have demonstrated superior efficacy to the FDA approved regimen of 250 mg/day x 12 weeks. Pulse therapies, though showing comparable effectiveness, present debates with regards to their efficacy as conflicting findings have been reported. Safety concerns encompass hepatotoxicity, gastrointestinal, cutaneous, neurologic, hematologic and immune adverse-effects, and possible drug interactions, suggesting the need for ongoing monitoring.

EXPERT OPINION

Terbinafine efficacy depends on dosage, duration, and resistance patterns. Continuous therapy for 24 weeks and a dosage of 500 mg/day may enhance outcomes, but safety considerations and resistance necessitate individualized approaches. Alternatives, including topical agents and alternative antifungals, are to be considered for resistant cases. Understanding the interplay between treatment parameters, adverse effects, and resistance mechanisms is critical for optimizing therapeutic efficacy while mitigating resistance risks. Patient education and adherence are vital for early detection and management of adverse effects and resistance, contributing to tailored and effective treatments.

The safety of oral antifungals for the treatment of onychomycosis

INTRODUCTION

Oral antifungals are used for the treatment of moderate-severe onychomycosis. Terbinafine and itraconazole are approved for onychomycosis treatment in North America; additionally, fluconazole is indicated for onychomycosis in Europe. Other oral antifungals such as ketoconazole and griseofulvin are no longer used for the treatment of onychomycosis due to safety concerns and relatively lower efficacy.

SEARCH STRATEGY

On 7 March 2023, we conducted a comprehensive search in PubMed and Google Scholar, while also manually examining selected article bibliographies and package inserts.

AREAS COVERED

Terbinafine, itraconazole, and fluconazole have several interactions with cytochrome-p450, and either alone, or when co-administered with other drugs these interactions can facilitate a multitude of adverse events. This article identifies possible hepatic, renal, cutaneous, cardiovascular, neurological, hemopoietic, and obstetric adverse events. We have also compared the rates of hepatotoxicity, clinically apparent liver injury, and alanine transaminase elevations between oral antifungals, and recommendations for hepatic monitoring.

EXPERT OPINION

We recommend laboratory testing of liver function tests prior to the administration of any oral antifungals, especially when clinically indicated. In the event of a first treatment failure, the diagnosis of onychomycosis must be confirmed, and consideration given to antifungal susceptibility testing. Antifungal stewardship will help reduce the incidence of antifungal resistance.

New possibilities for chromoblastomycosis and phaeohyphomycosis treatment: identification of two compounds from the MMV Pathogen Box® that present synergism with itraconazole

BACKGROUND

Black fungi of the Herpotrichiellaceae family are agents of chromoblastomycosis and phaeohyphomycosis. There are few therapeutic options for these infections and it is common to associate antifungal drugs in their treatment.

OBJECTIVES

To investigate the Medicines for Malaria Venture (MMV) Pathogen Box^® for possible compounds presenting synergism with antifungal drugs used to treat black fungal infections.

METHODS

An initial screening of the Pathogen Box^® compounds was performed in combination with itraconazole or terbinafine at sub-inhibitory concentrations against Fonsecaea pedrosoi. Hits were further tested against eight Herpotrichiellaceae using the checkerboard method.

FINDINGS

No synergism was observed with terbinafine. MMV687273 (SQ109) and MMV688415 showed synergism with itraconazole against F. pedrosoi. Synergism of these compounds was confirmed with some black fungi by the checkerboard method. SQ109 and itraconazole presented synergism for Exophiala dermatitidis, F. pedrosoi, F. monophora and F. nubica, with fungicidal activity for F. pedrosoi and F. monophora. MMV688415 presented synergism with itraconazole only for F. pedrosoi, with fungicidal activity. The synergic compounds had high selectivity index values when combined with itraconazole.

MAIN CONCLUSIONS

These compounds in combination, particularly SQ109, are promising candidates to treat Fonsecaea spp. and E. dermatitidis infections, which account for most cases of chromoblastomycosis and phaeohyphomycosis.

Drug-Drug Interactions With Over-The-Counter Medicines: Mind the Unprescribed

BACKGROUND

This review provides a summary of the currently available clinical data on drug-drug interactions (DDIs) involving over-the-counter (OTC) medicines. It aims to educate and increase awareness among health care providers and to support decisions in daily practice.

METHODS

An extensive literature search was performed using bibliographic databases available through PubMed.gov. An initial structured search was performed using the keywords "drug-drug-interaction AND (over-the-counter OR OTC)," without further restrictions except for the language. The initial results were screened for all described DDIs involving OTC drugs, and further information was gathered specifically on these drugs using dedicated database searches and references found in the bibliography from the initial hits.

RESULTS

From more than 1200 initial hits (1972-June 2021), 408 relevant publications were screened for DDIs involving OTC drugs, leading to 2 major findings: first, certain types of drug regimens are more prone to DDIs or have more serious DDI-related consequences, such as antiretroviral, anti-infective, and oral anticancer therapies. Second, although most DDIs involve OTC drugs as the perpetrators, some prescription drugs (statins or phosphodiesterase-5 inhibitors) that currently have OTC status can be identified as the victims in DDIs. The following groups were identified to be frequently involved in DDIs: nonsteroidal anti-inflammatory drugs, food supplements, antacids, proton-pump inhibitors, H2 antihistamines, laxatives, antidiarrheal drugs, and herbal drugs.

CONCLUSIONS

The most significant finding was the lack of high-quality evidence for commonly acknowledged interactions. High-quality interaction studies involving different phenotypes in drug metabolism (cytochrome P450) and distribution (transporters) are urgently needed. This should include modern and critical drugs, such as oral anticancer medications and direct oral anticoagulants.

Tinea Capitis by Microsporum canis in an Elderly Female with Extensive Dermatophyte Infection

Tinea capitis is a type of dermatophyte infection primarily affecting children. We report a case of an elderly woman with well-controlled diabetes mellitus presenting with a six-month history of erythema with yellow crusts on her scalp and extensive erythematous patches with scales on the body skin. She adopted a stray cat before the disease onset. Dermoscopic findings and manifestation under the Wood's lamp favoured the diagnosis of tinea capitis. Further microscopic examinations of her scalp, including direct KOH and fluorescence stain examination, fungal culture and polymerase chain reaction sequencing identification confirmed the diagnosis of tinea capitis caused by Microsporum canis. Treatment with oral terbinafine was effective. Adult tinea capitis is often misdiagnosed due to its rarity and atypical presentation. However, in some regions, the incidence of tinea capitis in immunocompetent adults is rising which requires the awareness of clinicians. A thorough history (including the animal contacting history), physical examination and further mycological examinations are required for diagnosis. Trichophyton violaceum is the most common dermatophyte species in most regions while adult tinea capitis caused by Microsporum canis is less common. Terbinafine, griseofulvin and itroconazole have been reported to be effective drugs for the treatment of tinea capitis, and terbinafine can be considered as systemic treatment in elderly patients with comorbidities to reduce the drug-drug interaction.

Safety of current therapies for onychomycosis

INTRODUCTION

Onychomycosis is the most common nail disease seen in clinical practice. Treatment options include systemic and topical therapies, as well as devices. Following clinical and mycologic diagnosis, treatment must be individualized, accounting for disease severity, infecting organism(s), comorbidities, patient characteristics and drug/device efficacy. Safety is the most important consideration in choosing the most appropriate therapeutic modality.

AREAS COVERED

This review covers currently available treatments for onychomycosis, with an emphasis on safety and tolerability. Medications and devices were analyzed for side effects, drug-drug interactions, and safety during pregnancy and breastfeeding.

EXPERT OPINION

Systemic antifungals offer greater efficacy for onychomycosis treatment but are limited by risks of systemic toxicity and drug-drug interactions. The risk of terbinafine-induced hepatotoxicity is negligible in healthy patients. Systemic therapies, especially azole antifungals, are associated with numerous drug-drug interactions, some of which are life-threatening and fatal. Thus, a detailed medication history is critical before prescribing these medications. Topical antifungals are well tolerated and generally safe, with only potential local side effects. Systemic and topical onychomycosis treatments should not be prescribed during pregnancy and breastfeeding. Laser therapy is likely less effective than systemic and topical therapies, but may be safely used during pregnancy and breastfeeding.

High-content analysis of constitutive androstane receptor (CAR) translocation identifies mosapride citrate as a CAR agonist that represses gluconeogenesis

The constitutive androstane receptor (CAR) plays an important role in hepatic drug metabolism and detoxification but has recently been projected as a potential drug target for metabolic disorders due to its repression of lipogenesis and gluconeogenesis. Thus, identification of physiologically-relevant CAR modulators has garnered significant interest. Here, we adapted the previously characterized human CAR (hCAR) nuclear translocation assay in human primary hepatocytes (HPH) to a high-content format and screened an FDA-approved drug library containing 978 compounds. Comparison of hCAR nuclear translocation results with the Tox21 hCAR luciferase reporter assay database in 643 shared compounds revealed significant overlap between these two assays, with approximately half of hCAR agonists also mediating nuclear translocation. Further validation of these compounds in HPH and/or using published data from literature demonstrated that hCAR translocation exhibits a higher correlation with the induction of hCAR target genes, such as CYP2B6, than the luciferase assay. In addition, some CAR antagonists which repress CYP2B6 mRNA expression in HPH, such as sorafenib, rimonabant, and CINPA1, were found to translocate hCAR to the nucleus of HPH. Notably, both the translocation assay and the luciferase assay identified mosapride citrate (MOS), a gastroprokinetic agent that is known to reduce fasting blood glucose levels in humans, as a novel hCAR activator. Further studies with MOS in HPH uncovered that MOS can repress the expression of gluconeogenic genes and decrease glucose output from hepatocytes, providing a previously unidentified liver-specific mechanism by which MOS modulates blood glucose levels.

A semi-mechanistic pharmacokinetic model of saquinavir combined with itraconazole in HIV-1-positive patients

The mechanism of drug-drug interaction between saquinavir, a protease inhibitor used effectively for HIV/AIDS treatment, and itraconazole, an azole antifungal agent, is hypothesized to involve competitive inhibition at CYP3A4 enzyme, an important drug metabolizing enzyme in humans. The resulting interaction between these CYP3A4 substrates can be utilized clinically as a pharmacokinetic booster for prolonging saquinavir dosing regimen and/or decreasing saquinavir dose requirement in HIV/AIDS patients. To quantitatively describe this specific drug-drug interaction, based on the existing data, we aimed to develop a mathematical model incorporated with the competitive inhibition phenomena. PlotDigitizer was used to extract data from literature. Advance Continuous Simulating Language Extreme (ACSLX), a FORTRAN-based computer program, was employed as our developing tool. Our computer model simulations could successfully describe concentration-time course of saquinavir from selected pharmacokinetic studies in HIV-1-positive patients. To extend the model's utility as an aid in saquinavir dosage regimens, the developed model may be applied to other HIV/AIDS patients in genuine clinical settings.

Improving Cure Rates in Onychomycosis

Background:

Onychomycosis is a persistent fungal nail infection that is notoriously hard to treat. Approximately 20% to 25% of patients with onychomycosis do not respond to treatment, and 10% to 53% of patients relapse. As such, successful treatment is imperative for long-term disease management.

Objective:

To identify ways to improve cure rates for onychomycosis.

Method:

The literature on onychomycosis treatment and recurrence was reviewed to summarize treatment approaches and suggest strategies to increase cure rates.

Results and Conclusion:

To improve treatment success in onychomycosis, we suggest the following measures be followed: (1) onychomycosis must be correctly diagnosed, (2) the treatment regimen should be tailored to the individual patient, (3) the efficacy of antifungals must be maximized, and (4) recurrence must be prevented.

Determining canine skin concentrations of terbinafine to guide the treatment of Malassezia dermatitis

BACKGROUND

Terbinafine (TBF) is known to concentrate and persist in human skin. Its use is increasing in veterinary medicine, but there are limited data concerning its tissue concentration and efficacy in dogs.

HYPOTHESIS/OBJECTIVES

(i) Describe TBF accumulation in canine skin; (ii) Integrate pharmacokinetic data with historical minimum inhibitory concentration (MIC) results for Malassezia pachydermatis to verify the currently used dosage of TBF for the treatment of Malassezia dermatitis.

ANIMALS

Ten healthy, client-owned dogs.

METHODS

Dogs were given TBF (generic preparation, 250 mg tablets) 30 mg/kg per os (p.o.) once daily for 21 days. Serum, sebum and stratum corneum (SC) samples were collected on days 1, 5, 7, 11, 14, 21, 28 and 35. High-pressure liquid chromatography was used to determine drug concentrations in samples.

RESULTS

Relevant (mean ± standard deviation) parameters for TBF in serum, paw SC, thorax SC and sebum, respectively, were: maximum concentration (Cmax , μg/mL) 23.59 ± 10.41, 0.31 ± 0.26, 0.30 ± 0.32 and 0.48 ± 0.25; half-life (t1/2 , d) 4.49 ± 2.24, 6.34 ± 5.33, 4.64 ± 3.27 and 5.12 ± 3.33; time to maximum concentration (Tmax , d) 10.40 ± 6.98, 13.20 ± 5.16, 11.90 ± 8.62 and 10.60 ± 3.69.

CONCLUSIONS AND CLINICAL IMPORTANCE

These results suggest that TBF does not achieve high concentrations in canine SC or sebum compared to serum. The mean Cmax of all skin tissues (paw SC, thorax SC and sebum) barely exceeded the reported Malassezia MIC90, of 0.25 μg/mL, which indicates that doses higher than 30 mg/kg p.o. once daily may be necessary.

Treatment of superficial mycoses: review. Part II

Superficial fungal infections of the hair, skin and nails are a major cause of morbidity in the world. Choosing the right treatment is not always simple because of the possibility of drug interactions and side effects. The first part of the article discusses the main treatments for superficial mycoses - keratophytoses, dermatophytosis, candidiasis, with a practical approach to the most commonly-used topical and systemic drugs , referring also to their dosage and duration of use. Promising new, antifungal therapeutic alternatives are also highlighted, as well as available options on the Brazilian and world markets.

Penicillium marneffei presenting as an immune reconstitution inflammatory syndrome (IRIS) in a patient with advanced HIV

A 62-year-old British man with advanced HIV was established on antiretroviral therapy and treatment for disseminated Mycobacterium avium complex and Cytomegalovirus infections. One month later he re-presented with epigastric pain, an epigastric mass and skin lesions. Abdominal imaging revealed large volume lymphadenopathy, which was not present on previous imaging. Blood cultures yielded Penicillium marneffei, a dimorphic fungus endemic to South-east Asia. The patient had spent several years travelling in Thailand prior to the diagnosis of HIV. Penicilliosis is a common AIDS-defining illness in endemic areas, but remains rare in Europe. In this case, it presented in the context of a rapidly decreasing viral load as an immune reconstitution inflammatory syndrome. The challenges of management in the context of multiple comorbidities and polypharmacy are discussed.

Comparison of once-daily versus twice-weekly terbinafine administration for the treatment of canine Malassezia dermatitis - a pilot study

BACKGROUND

Terbinafine, an allylamine antifungal, is used in pulsatile dose regimens for superficial mycoses in human medicine.

OBJECTIVES

To compare the clinical efficacy of twice-weekly versus once-daily terbinafine administration to determine whether preliminary proof-of-concept evidence exists for pulsatile administration of terbinafine in the treatment of canine Malassezia dermatitis and to determine whether twice-weekly treatment results in fewer clinical and owner-perceived adverse events.

ANIMALS

Twenty client-owned dogs with Malassezia dermatitis.

METHODS

In this randomized, single-blinded clinical trial, dogs were randomly assigned to receive terbinafine (30 mg/kg) either once daily for 21 days (n = 10) or once daily on two consecutive days per week for six doses (n = 10). On day 0 and day 21, a mean yeast count was calculated from eight anatomical locations via adhesive tape-strip cytology, clinical lesion scores were assigned to the same locations, and owners assessed pruritus using a visual analog scale.

RESULTS

There was no significant difference between treatment groups with respect to the reduction in mean yeast count (P = 0.343) and clinical lesion scores (P = 0.887). Pruritus measured by visual analog scale was significantly decreased in the twice-weekly treatment group compared with the daily treatment group (P = 0.047). Seven of 20 dogs had a clinically measurable or owner-reported adverse event during treatment that included gastrointestinal disturbances, excessive panting and elevated hepatic enzymes, with no significant difference noted between treatment groups.

CONCLUSIONS AND CLINICAL IMPORTANCE

This pilot study indicates that twice-weekly terbinafine administration may be an effective alternative treatment for canine Malassezia dermatitis and merits further investigation.

Combination immunotherapy of MAb B6.1 with fluconazole augments therapeutic effect to disseminated candidiasis

We recently reported that IgM MAb B6.1, specific for β-1, 2-mannotriose on the cell wall of Candida albicans, is therapeutic to disseminated candidiasis due to C. albicans. In the current study, we examined if MAbB6.1 enhances therapeutic effect of fluconazole (FLC) to the disseminated disease. To assess the combination effect, determination by the kidneys-colony forming unit and survival times were used. Results showed that the therapeutic effect of FLC on mice with disseminated candidiasis was dose-dependent, but a FLC dose at 0.8 mg/kg body weight of mice was ineffective. To determine combination effect, mice treated intraperitoneally with a combination of FLC plus MAb B6.1 at 1 h post-infection - a condition of developing partial therapeutic activity - enhanced survival times beyond the effect by only antibody (p < 0.05). The resulting MST (mean survival times) value from the combination-received mice was almost the same as MST value from 3.2 mg FLC dose-given animals (p < 0.05). Another combination of 1.6 mg FLC dose and B6.1 reduced severity of the disseminated disease at almost the same rate as combination efficacy of 0.8 mg FLC dose plus B6.1. This data indicates that B6.1 acts in concert with FLC and that this combination therapy augments protection, which suggests a possibility of reducing FLC dose. The augmentation response was specific because an irrelevant IgM MAb S9 was not effective to the disseminated disease. Thus, our present studies demonstrate that this combination immunotherapy may be a way of solving the problem of limited antifungal drug choices caused by drug-resistant C. albicans.

Toenail onychomycosis in diabetic patients: issues and management

Diabetes mellitus may be associated with serious sequelae, such as renal disease, retinopathy, and diabetic foot. A recent large prospective study has shown that onychomycosis is among the most significant predictors of foot ulcer. As the severity of onychomycosis may be associated with the length of time the individual has had the infection, early intervention is advisable owing to the progressive nature of the fungal infection. If left untreated, toenails can become thick, causing pressure and irritation, and thus act as a trigger for more severe complications. In the treatment of onychomycosis, compliance and drug interactions are important considerations, as diabetic patients frequently take concomitant medications. Terbinafine and itraconazole have been investigated for the treatment of onychomycosis in diabetic patients and have been shown to have efficacy and safety profiles comparable to those in the nondiabetic population. Data from clinical trials and postmarketing surveillance suggest that drug interactions resulting in hypoglycemia may not be an important issue when itraconazole and terbinafine are used to treat diabetic patients receiving concomitant hypoglycemic medications. Patient advice and education in improved foot care are an integral part of onychomycosis management, and help achieve long-term cure and reduce the complications of diabetic foot.

Oral antibiotic drug interactions of clinical significance to dermatologists

Oral antibiotics are commonly prescribed by dermatologists in clinical practice. When prescribing an oral antibiotic, as with other systemic medications, it is important to consider potential interactions with other drugs, including over-the-counter medications. The most common drug interaction mechanisms that may lead to clinically significant sequelae are inhibition of GI drug absorption and alterations in drug metabolism. Tetracycline and quinolones undergo chelation interactions with many metal ions found in antacids and mineral supplements. Some macrolides, such as erythromycin, inhibit the hepatic metabolism of many other drugs, increasing the risk for toxicity. Rifampin increases the metabolism of many other drugs, thus predisposing to treatment failure. Drug interactions can only be averted if their potential is understood and recognized in advance.

Global gene expression of Trichophyton rubrum in response to PH11B, a novel fatty acid synthase inhibitor

AIMS

To determine the transcriptional responses of Trichophyton rubrum to the artificial substance, PH11B.

METHODS AND RESULTS

The broth microdilution assay for antifungal susceptibility testing of dermatophytes was used to measure the minimum inhibitory concentration (MIC) of PH11B. cDNA microarray technology and real-time RT-PCR were used to study the transcriptional responses of T. rubrum to PH11B. The MIC determined was 16 microg ml(-1). The analysis of microarray data revealed that 787 genes were affected. Transcript levels from 476 genes increased at least two times, while 311 gene transcript levels decreased at least two times.

CONCLUSIONS

PH11B has strong antifungal activity and the transcriptional response of T. rubrum to PH11B was determined.

SIGNIFICANCE AND IMPACT OF THE STUDY

This microarray data set provides an analysis of gene expression of T. rubrum under PH11B treatment. The data provide an insight into the various metabolic processes altered or activated by PH11B. This study provided an insight into the action mode of the PH11B on T. rubrum.

Population pharmacokinetics of itraconazole and its active metabolite hydroxy-itraconazole in paediatric cystic fibrosis and bone marrow transplant patients

OBJECTIVE

The objective of the study was to characterise the population pharmacokinetic properties of itraconazole and its active metabolite hydroxy-itraconazole in a representative paediatric population of cystic fibrosis and bone marrow transplant (BMT) patients and to identify patient characteristics influencing the pharmacokinetics of itraconazole. The ultimate goals were to determine the relative bioavailability between the two oral formulations (capsules vs oral solution) and to optimise dosing regimens in these patients.

METHODS

All paediatric patients with cystic fibrosis or patients undergoing BMT at The Royal Children's Hospital, Brisbane, QLD, Australia, who were prescribed oral itraconazole for the treatment of allergic bronchopulmonary aspergillosis (cystic fibrosis patients) or for prophylaxis of any fungal infection (BMT patients) were eligible for the study. Blood samples were taken from the recruited patients as per an empirical sampling design either during hospitalisation or during outpatient clinic visits. Itraconazole and hydroxy-itraconazole plasma concentrations were determined by a validated high-performance liquid chromatography assay with fluorometric detection. A nonlinear mixed-effect modelling approach using the NONMEM software to simultaneously describe the pharmacokinetics of itraconazole and its metabolite.

RESULTS

A one-compartment model with first-order absorption described the itraconazole data, and the metabolism of the parent drug to hydroxy-itraconazole was described by a first-order rate constant. The metabolite data also showed one-compartment characteristics with linear elimination. For itraconazole the apparent clearance (CL(itraconazole)) was 35.5 L/hour, the apparent volume of distribution (V(d(itraconazole)) was 672 L, the absorption rate constant for the capsule formulation was 0.0901 h(-)(1) and for the oral solution formulation was 0.96 h(-1). The lag time was estimated to be 19.1 minutes and the relative bioavailability between capsules and oral solution (F(rel)) was 0.55. For the metabolite, volume of distribution, V(m)/(F . f(m)), and clearance, CL/(F . f(m)), were 10.6L and 5.28 L/h, respectively. The influence of total bodyweight was significant, added as a covariate on CL(itraconazole)/F and V(d(itraconazole))/F (standardised to a 70 kg person) using allometric three-quarter power scaling on CL(itraconazole)/F, which therefore reflected adult values. The unexplained between-subject variability (coefficient of variation %) was 68.7%, 75.8%, 73.4% and 61.1% for CL(itraconazole)/F, V(d)((itraconazole)())/F, CL(m)/(F . f(m)) and F(rel), respectively. The correlation between random effects of CL(itraconazole) and V(d(itraconazole)) was 0.69.

CONCLUSION

The developed population pharmacokinetic model adequately described the pharmacokinetics of itraconazole and its active metabolite, hydroxy-itraconazole, in paediatric patients with either cystic fibrosis or undergoing BMT. More appropriate dosing schedules have been developed for the oral solution and the capsules to secure a minimum therapeutic trough plasma concentration of 0.5 mg/L for these patients.

Safety and efficacy of oral terbinafine in the treatment of onychomycosis: Analysis of the elderly subgroup in improving results in ONychomycosis-concomitant lamisil® and debridement (IRON-CLAD), an open-label, randomized trial

OBJECTIVES

The primary objective of this subanalysis was to examine the safety, tolerability, and efficacy of terbinafine in the treatment of toenail onychomycosis in the patients aged > or = 65 years in the Improving Results in Onychomycosis Concomitant Lamisil And Debridement (IRON-CLAD) trial. (Lamisil and IRON-CLAD are trademarks of Novartis Pharmaceuticals Corporation, East Hanover, New Jersey.) The secondary objective was to determine if toenail debridement would provide additional efficacy benefits in this subgroup.

METHODS

The IRON-CLAD trial was an open-label, randomized, multicenter study of adults who underwent 4 weeks of screening and received terbinafine 250 mg/d for 12 weeks with or without aggressive toenail debridement (at baseline and weeks 6, 12, and 24). Clinic visits occurred at weeks 6, 12, 24, and 48. Safety and tolerability were assessed by adverse event (AE) rates based on changes in laboratory values, patient-volunteered information, answers to investigator questions, and physical examinations. Efficacy was evaluated by mycologic cure (negative microscopy of potassium hydroxide samples and negative culture), clinical cure (> or = 87.5% nail clearing), and complete cure (mycologic cure and complete toenail clearing) at week 48. The present subanalysis of IRON-CLAD results assessed participants aged > or = 65 years (older subgroup).

RESULTS

A total of 504 patients were randomized, of whom 75 were aged > or = 65 years. In the older subgroup, the mean (SD) age was 68.9 (3.04), 86.7% (65/75) were white, and 66.7% (50/75) were male. Incidence of AEs reported during the treatment period or within 30 days after treatment discontinuation (treatment-emergent AEs [TEAEs]) was 28.0% in the older subgroup and 23.0% in the overall study population. Most TEAEs were mild (73.7%) to moderate (23.7%) in severity, and most (86.8%) were not suspected by the investigators to be related to study treatment. The most frequently occurring TEAEs in the older subgroup were nausea (4.0%), sinusitis (4.0%) arthralgia (2.7%), and hypercholesterolemia (2.7%). The proportion of participants who withdrew from the trial due to TEAEs was 4.0% (3/75) in the older group and 2.8% (14/504) in the overall population. Only 3 of 11 discontinuations in the older subgroup were due to a TEAE suspected by the investigator to be related to study treatment. Sixty-four percent of the older subgroup took antihypertensive medications, 25% took antidiabetics, and 47% took antilipemic medications. There were no clinical signs of drug interactions in the older subgroup. Clinical efficacy outcomes in the older subgroup were generally good and appeared to be comparable with those in the younger subgroup. At week 48, mycologic cure had occurred in 64.0% (95% CI, 53.1%-74.9%) of the older subgroup, clinical cure in 41.3% (95% CI, 30.2%-52.5%), and complete cure in 28.0% (95% CI, 17.8%-38.2%). Debridement did not appear to affect mycologic outcomes or clinical effectiveness, but rates of clinical and complete cure appeared to be higher among older patients who underwent adjuvant debridement.

CONCLUSIONS

The results of this subanalysis suggest that terbinafine was well tolerated and efficacious in these patients aged > or = 65 years with moderate to severe toenail onychomycosis, many of whom were taking antihypertensives, antidiabetics, or lipid-lowering agents concomitantly. There were no reported clinical signs of drug interactions.

Subcutaneous phaeohyphomycosis caused byPhaeoacremonium parasiticumin a renal transplant patient

A 49-year-old renally transplanted man, under a five-year course of immunosuppressive therapy with prednisone and cyclosporine A, experienced a subcutaneous phaeohyphomycosis caused by Phaeoacremonium parasiticum. The clinical presentation consisted of impressive, large, inflammatory and draining cystic tumors on the left foot that had been present for one year. A significant improvement was obtained with itraconazole plus intralesional injection with amphotericin B. Drug interaction was observed between itraconazole and cyclosporine A causing a severe hypertensive crisis and requiring a temporary sharp reduction in cyclosporine administration. Subcutaneous phaeohyphomycosis caused by P. parasiticum is uncommon among major organ transplant patients but several cases have previously been published and some patterns are emerging, e.g., limbs are generally involved but no known traumatic event has preceded lesion development. The identification of the case isolate was confirmed using a recently published online system based in part on beta-tubulin sequence comparison.

Current use of anti-infectives in dermatology

Dermatologic diseases encompass a broad category of pathologic situations. Infection remains a significant aspect of the pathology faced in patient encounters, and it is natural to expect that anti-infectives play a major element in the armamentarium utilized by dermatologists. Aside from the treatment of the classic bacterial and fungal infections, there are now new uses for antiviral agents to help suppress recurrent disease, such as herpes simplex. There is also the novel approach of using anti-infectives, or agents that have been thought to have antimicrobial activity, to treat inflammatory diseases. This review describes anti-infectives, beginning with common antibiotics used to treat bacterial infections. The discussion will then cover the current use of antivirals. Finally, the description of antifungals will be separated, starting with the oral agents and ending with the topical antimycotics. The use of anti-infectives in tropical dermatology has been purposefully left out, and perhaps should be the subject of a separate review. Cutaneous bacterial infections consist chiefly of those microorganisms that colonize the skin, such as species of staphylococcus and streptococcus. Propionibacterium acnes and certain other anaerobes can be involved in folliculitis, pyodermas and in chronic conditions such as hidradenitis suppurativa.

Treatment of onychomycosis with oral antifungal agents

Onychomycosis is the most common nail disease and describes the invasion of the nail by fungi. Different clinical patterns of infection depend on the way and the extent by which fungi colonise the nail: distal subungual onychomycosis, proximal subungual onychomycosis, white superficial onychomycosis, endonyx onychomycosis and total dystropic onychomycosis. The type of nail invasion depends on both the fungus responsible and on host susceptibility. Treatment of onychomycosis depends on the clinical type of the onychomycosis, the number of affected nails and the severity of nail involvement. The goals for antifungal therapy are mycological cure and a normal looking nail. In this paper the treatment of onychomycosis with oral antifungal agents will be reviewed.

Pharmacotherapy of onychomycosis

Fungal infections of the nails are frequent in some segments of the population. Dermatophytes, yeasts and moulds are potential pathogens. A series of antifungal treatments are available to the clinician, differing by both their mechanistic nature and mode of administration. The pharmacodynamic and pharmacokinetic properties of each antifungal agent are distinct. This review focuses on the characteristics of amorolfine, bifonazole, ciclopirox, fluconazole, griseofulvin, itraconazole, ketoconazole, ravuconazole, R126638 and terbinafine. Single drug treatments and combined therapies are presented. None of the current drug regimens have demonstrated reliable efficacy against all cases of onychomycosis. Treatment failures, relapses and reinfections remain stubborn problems in the management of onychomycosis.

Kutane Alternariose

Localized skin infections caused by the pigmented fungi of the genus Alternaria are being increasingly observed. In the past, primarily patients receiving long-term glucocorticoid therapy were likely to have this mycosis, which is commonly traumatic, but now it is frequently encountered in organ transplantation patients. Possible therapeutic options and differential diagnosis are discussed by means of two case reports--a female renal transplant patient infected by A. alternata and a patient with iatrogenic Cushing syndrome infected by A. infectoria. Histopathological differentiation from other fungal infections may be difficult but is of therapeutic and prognostic significance. Finding short hyphae in tissue sections is an important clue. Since A. infectoria shows little conidial growth in culture, rDNA ITS sequencing offers another diagnostic possibility. Therapy has not yet been standardized. Along with surgical intervention, systemic itraconazole is the usual choice.

Drug interactions of clinical significance for the dermatologist: recognition and avoidance

While it would be impossible for any dermatologist to remember all potential drug interactions, knowledge of the mechanisms of drug interactions can help reduce the risk of serious adverse outcomes. Most drugs are associated with interactions but the majority do not produce significant outcomes. Dealing with drug interactions is a challenge in all clinical practice, including dermatology. New information continues to appear, and dermatologists need to know about the drugs they use.This article focuses on the mechanisms of drug interactions. In particular, the life of a drug in terms of absorption, distribution, metabolism and excretion are reviewed with the focus on points of importance and relevance to drug interactions. The most clinically important drug interactions in dermatological practice are caused by alterations in drug metabolism. The contributions of P-glycoprotein, pharmacogenetic variation and genetic polymorphisms to drug interactions are highlighted, and the best evidence for drug interactions involving drug classes relevant to the dermatologist is presented. Since the initial evidence for clinically relevant drug interactions comes from case reports, prescribing physicians can have a major role in collating information on interactions. By understanding the mechanisms behind drug interactions and staying alert for toxicities, we can help make drug therapy safer and reduce the fear of drug interactions.

Cutaneous fungal infections in the elderly

Because of impaired host defenses and a favorable environment at specific anatomic sites, there is an increased prevalence of seborrheic dermatitis, mucosal and cutaneous candidiasis, tinea pedis, and onychomycosis in the geriatric population compared with other age groups. Both KOH and fungal culture are timely, convenient, and cost-effective methods of diagnosis. Sensitivity of these tests depends on proper technique for specimen collection and experience. KOH 20% with DMSO and DTM are highly recommended. Treatment should be tailored to the diagnosis and the individual patient. This includes the targeted spectrum of coverage (dermatophyte or yeast); topical versus systemic therapy; review of the patient's medication list for potential drug interactions; and likelihood of compliance. Checking baseline laboratories and routine monitoring of complete blood count and liver function tests in healthy patients, without a history of liver disease or active hepatitis, and without potential drug interactions, seems unwarranted for rare adverse events. Successful management requires adequate patient education, correction of underlying predisposing factors, and prophylactic measures against recurrence.

Abbreviated oral itraconazole therapy for tinea corporis and tinea cruris

The present study was designed to determine the lowest dose of orally administered itraconazole and the shortest duration of therapy necessary for treatment of tinea corporis and tinea cruris. For all patients, the itraconazole dose was 100 mg twice a day immediately after meals. Twenty-eight patients received itraconazole on days 1 and 8, 12 patients received itraconazole on days 1 and 2, and five patients received itraconazole only on day 1. Clinical and mycological evaluations were performed at baseline and on day 14. Based on the clinical and mycological responses, treatment efficacy was classified as excellent, good, fair, or poor. "Excellent" and "good" responses made up 86% of the first group, 100% of the second group, and 20% of the third group. A comparison of efficacy ratings of the three regimens showed that the patients who received a single 200-mg dose had a significantly inferior outcome compared with the other two groups. We conclude that an abbreviated oral regimen of itraconazole for treatment of tinea corporis and tinea cruris requires a total dose of at least 400 mg to induce a favorable outcome.

Oral antifungal drug interactions: a mechanistic approach to understanding their cause

Oral antifungal drugs are generally regarded as effective and safe when used according to their manufacturer's recommendation. However, when an oral antifungal agent is administered with certain interacting agents or classes of drugs, rare severe iatrogenic adverse experiences including death may occur. This article alerts and demystifies some of the clinically significant oral antifungal drug interactions by exploring their underlying pharmacological basis.

Interaction of all-trans-retinoic acid with fluconazole in acute promyelocytic leukemia

All-trans-retinoic acid (ATRA) has a dramatic antitumor effect in patients with acute promyelocytic leukemia (APL). It is hepatically metabolized by cytochrome P-450, and there are known toxicities associated with high levels of this drug. The effects of ATRA can be potentiated by inhibition of cytochrome P-450, which is known to occur with certain drugs. We report a case of a patient with ATRA toxicity thought to be secondary to interaction with fluconazole.

Important drug interactions and reactions in dermatology

A constantly expanding pharmacological armamentarium increases the concern for serious drug interactions. This article discusses drug metabolism and how the cytochrome P-450 family facilitates drug biotransformation. Clinically significant drug interactions involving antifungal drugs, antibiotics, retinoids, and immunosuppressive agents, as well as topical anesthetics and various foods, are included.

Therapeutic efficacy of topically applied KP-103 against experimental tinea unguium in guinea pigs in comparison with amorolfine and terbinafine

The therapeutic efficacy of KP-103, a novel topical triazole, in a guinea pig tinea unguium model was investigated. Experimental tinea unguium and tinea pedis were produced by inoculation of Trichophyton mentagrophytes SM-110 between the toes of the hind paw of guinea pigs. One percent solution (0.1 ml) of KP-103, amorolfine, or terbinafine was topically applied to the nails and whole sole of an infected foot once daily for 30 consecutive days, and terbinafine was also orally administered at a daily dose of 40 mg/kg of body weight for 30 consecutive days, starting on day 60 postinfection. The fungal burdens of nails and plantar skin were assessed using a new method, which makes it possible to recover infecting fungi by removing a carryover of the drug remaining in the treated tissues into the culture medium. Topically applied KP-103 inhibited the development of nail collapse, significantly reduced the fungal burden of the nails, and sterilized the infected plantar skin. On the other hand, topical amorolfine and topical or oral terbinafine were ineffective for tinea unguium, although these drugs eradicated or reduced the fungal burden of plantar skin. The in vitro activities of amorolfine and terbinafine against T. mentagrophytes SM-110 were 8- and 32-fold, respectively, decreased by the addition of 5% keratin to Sabouraud dextrose broth medium. In contrast, the activity of KP-103 was not affected by keratin because its keratin affinity is lower than those of the reference drugs, suggesting that KP-103 largely exists in the nails as an active form that was not bound to keratin and diffuses in the nail without being trapped by keratin. The effectiveness of KP-103 against tinea unguium is probably due to its favorable pharmacokinetic properties in the nails together with its potent antifungal activity.

Experimental tinea unguium model to assess topical antifungal agents using the infected human nail with dermatophyte in vitro

Therapy for onychomycosis is difficult because a complete cure requires long-term treatment. Although strong systemic antifungal drugs are potent enough to achieve a cure, they often have side effects. Therefore, one approach is to develop a new topical antifungal drug to act directly on the nail tissue. In this study, we developed a new in vitro model for assessing antifungal activity using the human nail. An O-ring was fixed with silicon bond to the dorsal surface of the nail. An antifungal agent applied to the surface will penetrate the nail tissue. The ventral side of the nail was placed on an agar plate inoculated with conidia of Trichophyton mentagrophytes. Nail specimens were infected with the fungi from the agar, and a clear fungal colony formed on the agar surrounding the nail on the fifth day of cultivation. After 14 days, the fungal colony in the control groups was shown to be expanding over the entire nail. The fungal colony in the group treated with sodium pyrithione had disappeared. Although the in vitro antifungal activity of sodium pyrithione has poor potency among the agents used, it showed remarkable antifungal activity, as assessed by image analysis. This model enables one to evaluate the activity of a topical antifungal agent that has penetrated human nail tissue, and it may facilitate research on a topical agent for onychomycosis.

Onychomycosis: strategies to improve efficacy and reduce recurrence

Fungal infections may be difficult to treat for several reasons. It is important to obtain the correct diagnosis, and select the appropriate antifungal agent and route. General considerations that may be associated with recurrent infections are, a genetic predisposition and suboptimal bioavailability of drug, resulting in insufficient concentration at the target site. The aetiologic organism, the severity of disease, other coexisting diseases, concomitant drug intake, and the presence of fungal infection at other sites are some factors that determine the choice of antifungal therapy and its route of administration, oral vs. topical lacquer. Local factors such as the thickness of the nail, presence of lateral onychomycosis, longitudinal spike, dermatophytoma and severe onycholysis are some factors that may determine the choice of secondary measures such as mechanical or topical treatment. Booster or supplemental therapy may be of benefit when the response to initial treatment is poorer than expected and unlikely to result in complete response. Steps should be taken to reduce the possibility of recurrence once cure has been achieved.

Drug interactions: Proteins, pumps, and P-450s

The two major concerns in drug safety are adverse drug reactions and drug interactions. When multiple drug therapies are prescribed, drug interactions become an important consideration for patients and physicians. The life of a drug is reviewed with emphasis on absorption, distribution, metabolism, and excretion. Pharmacokinetic and pharmacodynamic mechanisms for drug interactions are reviewed. The contributions of P-glycoprotein, pharmacogenetic variation, and genetic polymorphisms to drug interactions are highlighted. Prediction of drug interactions is possible with knowledge of which agents are likely to cause alterations in drug metabolism. (J Am Acad Dermatol 2002;47:467-84.)

LEARNING OBJECTIVE

At the conclusion of this learning activity, participants should have an understanding of the life of a drug. This knowledge should help predict important potential drug interactions.

Fungal skin infections in organ transplant recipients

Transplantation is now currently and increasingly performed for the treatment of various acute and chronic diseases. Today the kidney, heart, lung, heart-lung, liver, pancreas, kidney-pancreas, small bowel and bone marrow are being transplanted. The immunological status of patients receiving such transplants exposes them to the risk of developing bacterial, viral and fungal infections. The etiological agents of mycotic diseases involving the skin of transplant recipients range from the common dermatophytes through yeasts such as Candida spp., Malassezia spp. and dimorphic fungi to the emerging molds Fusarium spp. and Pseudallescheria boydii. The very wide spectrum of fungi causing cutaneous disease produces equally varied clinical aspects. Lesions may be typical, but are very often aspecific or ambiguous. Cutaneous lesions may be the sign of a trivial mycotic disease or the marker of a disseminated, potentially lethal fungal illness, so great attention should be given to their early recognition. Cutaneous manifestations due to Candida spp., Aspergillus spp., dematiaceous fungi and Pityrosporum folliculitis are usually observed early after transplant, cryptococcosis more than 6 months later, while the frequency of dermatophytoses increases as time goes by. Coccidioides immitis, Histoplasma capsulatum and Blastomyces dermatitidis may appear any time after transplantation. The management of the more severe forms of cutaneous mycosis in transplant recipients is difficult. Besides the fact that early recognition is not easy, there are also problems regarding the effectiveness and the toxicity of the therapy and drug-drug interactions. Prophylactic measures to avoid fungal contamination must be performed during hospitalization; patients should be taught how to avoid contamination, not only during the first period after transplantation, when high dosage immunosuppressive drugs are given, but also later when a normal lifestyle is resumed.

Terbinafine (Lamisil) treatment of toenail onychomycosis in patients with insulin-dependent and non-insulin-dependent diabetes mellitus: a multicentre trial

BACKGROUND

Diabetes mellitus (DM) affects an estimated 175 million people world-wide. Approximately one-third of patients with DM have toenail onychomycosis.

OBJECTIVES

To determine the efficacy and safety of terbinafine treatment of toenail onychomycosis in patients with DM receiving insulin and/or oral antidiabetic agents. Special interest was focused on potential drug interactions with oral hypoglycaemic substances.

METHODS

In a multicentre trial, patients suffering from insulin-dependent DM (IDDM) or non- insulin-dependent DM (NIDDM) with toenail onychomycosis were treated for 12 weeks with oral terbinafine 250 mg daily and followed up to 48 weeks. In addition to clinical, mycological and laboratory investigations, blood glucose levels were monitored.

RESULTS

At the end of the trial (week 48), a mycological cure rate of 73% was achieved. The rates of clinical cure and complete cure (mycological cure plus clinical cure) were 57% and 48%, respectively. There was no statistically significant difference between the NIDDM and IDDM groups with respect to the cure rates (P > 0.05). No hypoglycaemic episode was reported and none of the patients had hypoglycaemia during the treatment phase.

CONCLUSIONS

With excellent cure rates and a good tolerability profile, terbinafine should continue to be a drug of choice for the treatment of toenail onychomycosis in the rising number of NIDDM patients receiving multiple medication.

Focal nodular hyperplasia of the liver after intraconazole treatment

A 38-year-old woman developed focal nodular hyperplasia of the liver after she had received a 4-month treatment with intraconazole 200 mg/d for a fungal infection of her fingernails. Because the patient underwent yearly liver ultrasound examinations because of the removal of a breast carcinoma, when the tumor was discovered incidentally, it was clear that it had developed within the past year after she had begun receiving intraconazole. Although various chemical agents and drugs have been considered as possible etiologic factors in the development of focal nodular hyperplasia of the liver, cases occurring after intraconazole therapy have not been reported before. Apart from the theoretical considerations with regard to the pathogenesis of nodular hyperplasia of the liver, this case could gain practical importance, as it shows a new adverse effect of a drug that has been used in more than 34 million patients over the past 10 years. Furthermore, this case should draw attention to the possibility of drug-induced benign hepatic tumors, as they may mimic malignant and metastatic disorders, which might be especially alarming in patients undergoing routine examinations after removal of malignant tumors, such as our patient.

Pharmacology of itraconazole

Itraconazole is a triazole antifungal agent that has a broad spectrum of activity and is well tolerated. Itraconazole is highly efficacious, particularly because its main metabolite, hydroxy-itraconazole, also has considerable antifungal activity. The original capsule formulation of itraconazole may lead to variability in absorption and the plasma concentration. For the treatment of superficial fungal infections, this is not problematical because itraconazole accumulates at the infection site, making consistently high plasma concentrations unnecessary -- a characteristic that has been exploited in the development of a pulse regimen. Because consistent plasma concentrations are critical for the more serious systemic fungal infections, variable absorption of itraconazole from the capsules limits their application. Moreover, underlying disease processes and medical interventions can reduce absorption from the capsules in some patients with systemic fungal infections. To widen the beneficial application of itraconazole to include such patients, an oral solution and an intravenous formulation were developed. These formulations combine lipophilic itraconazole with hydroxypropyl-beta-cyclodextrin, a ring of substituted glucose molecules, which improves the solubility of itraconazole. The enhanced absorption and bioavailability of itraconazole from these new formulations make them ideal for the treatment of systemic fungal infections in a wide range of patient populations. The additional flexibility offered by the different routes of administration also means that itraconazole can be used in patients at high risk, such as children or those requiring intensive care, for whom the capsule formulation may be impractical.

Current management of fungal infections

The management of superficial fungal infections differs significantly from the management of systemic fungal infections. Most superficial infections are treated with topical antifungal agents, the choice of agent being determined by the site and extent of the infection and by the causative organism, which is usually readily identifiable. One exception is onychomycosis, which usually requires treatment with systemically available antifungals; the accumulation of terbinafine and itraconazole in keratinous tissues makes them ideal agents for the treatment of onychomycosis. Oral candidiasis in immunocompromised patients also requires systemic treatment; oral fluconazole and itraconazole oral solution are highly effective in this setting. Systemic fungal infections are difficult to diagnose and are usually managed with prophylaxis or empirical therapy. Fluconazole and itraconazole are widely used in chemoprophylaxis because of their favourable oral bioavailability and safety profiles. In empirical therapy, lipid-associated formulations of amphotericin-B and intravenous itraconazole are safer than, and at least as effective as, conventional amphotericin-B (the former gold standard). The high acquisition costs of the lipid-associated formulations of amphotericin-B have limited their use.

Oral antifungals as prophylaxis in haematological malignancy

In the standard treatment of patients with haematological malignancy, immunosuppressive therapy produces prolonged periods of neutropenia and mucositis, which increase the risk of systemic fungal infection. In allogeneic bone marrow transplantation, this risk extends well beyond the period of neutropenia when graft-versus-host disease, and its treatment, result in prolonged lymphocytopenia. Various agents are used for antifungal prophylaxis and treatment but all have limitations: amphotericin B is restricted by the need for intravenous infusion and the occurrence of adverse events, fluconazole by its narrow spectrum of activity and the emergence of fluconazole-resistant fungi and itraconazole capsules by erratic absorption. Oral administration of antifungals has clear advantages in prophylaxis and an important current strategy is to maximize the extent and reliability of the oral bioavailability of antifungal agents. Mucositis is the main obstacle for success of strategies based on oral delivery. In this review, the ability of these new oral formulations to deliver sufficient antifungal prophylaxis is evaluated.