A questionnaire study on the management of onychomycosis: a Canadian perspective

BACKGROUND

Onychomycosis of the toenails is a condition that responds poorly to griseofulvin. The introduction of terbinafine in Canada in May 1993 resulted in a marked shift in the choice of treatment for pedal onychomycosis.

METHODS

A questionnaire survey was carried out in 1996 among Canadian dermatologists regarding the management of onychomycosis.

RESULTS

There were 160 respondents from the roughly 350 practicing dermatologists. The dermatologists saw 8 +/- 0.6 patients per week (average +/- standard error (SE) with suspected or diagnosed onychomycosis, with 5 +/- 0.5 patients per week consulting the dermatologists for the first time. Most dermatologists performed mycological testing prior to starting treatment for onychomycosis. The management options for onychomycosis (mean +/- SE) were oral systemic antifungal therapy 51 +/- 3%, no therapy 31 +/- 3%, and nondrug therapy 9 +/- 2%. The majority of dermatologists (83%) used terbinafine as first-line therapy if, indeed, they used oral antifungal agents. In contrast, griseofulvin and ketoconazole were used as first-line therapy in 5% and 1% of cases, respectively. In Canada, there are no monitoring requirements when using oral terbinafine for onychomycosis. Therefore, it is not surprising that only 30% of dermatologists performed monitoring with terbinafine. In contrast, the frequency of monitoring with griseofulvin and ketoconazole was 40% and 80%, respectively. The subset of dermatologists who reported monitoring carried it out in only a fraction of their patients: 47%, 53% and 83% for terbinafine, griseofulvin, and ketoconazole, respectively. Therefore, the overall number of patients in whom regular monitoring was performed was 14.1% 21.2%, and 71.4% for terbinafine, griseofulvin, and ketoconazole, respectively. The perceived cure rates with terbinafine and griseofulvin (mean +/- SE) were 83.7 +/- 1% and 41 +/- 3.1%, respectively.

CONCLUSIONS

In May 1996, within three years of the introduction of terbinafine to Canada, this agent has become the drug of choice for the treatment of pedal onychomycosis (at the time of the survey neither itraconazole or fluconazole were approved for onychomycosis). Terbinafine has been found to be very effective and safe, and only a minority of dermatologists perform regular monitoring with this drug.

An overview of topical antifungal therapy in dermatomycoses. A North American perspective

Dermatophytes cause fungal infections of keratinised tissues, e.g. skin, hair and nails. The organisms belong to 3 genera, Trichophyton, Epidermophyton and Microsporum. Dermatophytes may be grouped into 3 categories based on host preference and natural habitat. Anthropophilic species predominantly infect humans, geophilic species are soil based and may infect both humans and animals, zoophilic species generally infect non-human mammals. It is important to confirm mycologically the clinical diagnosis of onychomycosis and other tinea infections prior to commencing therapy. The identity of the fungal organism may provide guidance about the appropriateness of a given topical antifungal agent. Special techniques may be required to obtain the best yield of fungal organisms from a given site, especially the scalp and nails. It is also important to realise the limitations of certain diagnostic aids e.g., Wood's light examination is positive in tinea capitis due to M. canis and M. audouinii (ectothrix organisms); however, Wood's light examination is negative in T. tonsurans (endothrix organism). Similarly, it is important to be aware that cicloheximide in culture medium will inhibit growth of non-dermatophytes. Appropriate media are therefore required to evaluate the growth of some significant non-dermatophyte moulds. For tinea infections other than tinea capitis and tinea unguium, topical antifungals may be considered. For effective therapy of tinea capitis an oral antifungal is generally necessary. Similarly, oral antifungals are the therapy of choice, especially if onychomycosis is moderate to severe. Furthermore, where the tinea infection involves a large area, in an immunocompromised host or if infection is recurrent with poor response to topical agents, then oral antifungal therapy may be necessary. Topical antifungal agents may be broadly divided into specific and nonspecific agents. The former group includes the polyenes, azoles, allylamines, amorolfine, ciclopirox and butenafine. Generally the topical agent is available as a cream, sometimes for use intravaginally. Less commonly, the formulation may be in the form of a powder, lacquer, spray, gel or solution. Many of these agents have a broad spectrum of activity, being effective against dermatophytes, yeasts and Malassezia furfur. For the treatment of tinea corporis, tinea cruris tinea versicolor and cutaneous candidosis, once or twice daily application may be required, the most common duration of therapy being 2 to 4 weeks. For tinea pedis the most common treatment duration is 4 to 6 weeks.

The risks of systemic corticosteroid use

Because of their potent antiinflammatory and immunosuppressive properties, systemic corticosteroids are used to modify a vast array of diseases. This class of drugs, however, has the potential to produce multiple adverse effects presenting the dermatologist with difficult decisions in the management of patients with potentially steroid responsive disorders. This article reviews the side effects of systemic corticosteroids, comments on strategies to minimize these side effects, as well as, outlining suggested mechanisms by which physicians may minimize the risks of medical legal consequences owing to adverse reactions to these drugs.

A double-blind, randomized, placebo-controlled trial of eutectic lidocaine/prilocaine cream 5% (EMLA) for analgesia prior to cryotherapy of warts in children and adults

Liquid nitrogen cryotherapy is an effective treatment modality for verrucae in children. However, sometimes the pain of the procedure is too much for the young child. In such instances the availability of an effective topical anesthetic would be of tremendous benefit. Warts are usually present on hardened skin, that is, the palms, periungual areas, and soles. In a double-blind, randomized, placebo-controlled, single-center, parallel-group trial with one visit, children (6-18 years old) and adults (>18 years old) had 2.5 g of lidocaine/prilocaine cream 5% applied under an occlusive dressing to the wart and a 1 to 2 mm area surrounding it 1 hour prior to liquid nitrogen cryotherapy. In both age groups the warts were subdivided by location-hardened skin areas versus nonhardened skin sites. The topical anesthetic was then removed and cryotherapy applied for 5 to 10 seconds. The pain of cryotherapy was assessed by the patient on a visual analogue scale (VAS) immediately after the cryotherapy and 4 and 8 hours later. There was no statistically significant difference in the pain of cryotherapy experienced following the application of active cream (n = 64) and placebo (n = 64). Exploratory subgroup analysis by wart location showed promising results for lidocaine/prilocaine cream 5% over placebo in children with warts on hardened skin sites (palms and soles). The topical anesthetic was safe and generally well-tolerated. Lidocaine/prilocaine cream 5% may provide some anesthesia in children receiving cryotherapy when the wart is on the palms or soles. Further studies are needed to better understand the site and age specificity of the anesthetic properties of lidocaine/prilocaine cream 5% when used to reduce the pain experienced during cryotherapy of warts.

Hepatitis associated with terbinafine therapy: three case reports and a review of the literature

Terbinafine is an allylamine antifungal agent first launched in the USA in May 1996 with an estimated 7.5 million individuals worldwide having used the drug. Given orally it is effective for the treatment of dermatophyte infections and is prescribed predominantly for the superficial mycoses. Adverse effects have been reported in 46.7% of patients receiving the oral drug (compared with 29.2% receiving placebo, the attributable risk to terbinafine being 17.5%). Thus, oral terbinafine is associated with the rare development of symptomatic idiosyncratic hepatobiliary dysfunction (1:45,000-1:54,000) and we now describe three patients who developed this disorder whilst taking the medication. The hepatitis produced has the features of both hepatocellular necrosis (with elevations of hepatic enzyme concentrations) and cholestatic injury (with elevations of alkaline phosphatase and cholesterol levels), the latency period between the start of medication and the development of liver injury being approximately 4-6 weeks. The US terbinafine product monograph recommends that serum hepatic enzymes should be assessed in individuals receiving terbinafine for more than 6 weeks, as a result of which some physicians monitor these values at baseline and at 4-6 weeks.

Cutaneous adverse effects associated with terbinafine therapy: 10 case reports and a review of the literature

Terbinafine is an allylamine antifungal agent widely used to treat dermatophyte onychomycosis and dermatomycoses. We report 10 severe cutaneous adverse reactions associated with terbinafine therapy which required discontinuation of the antifungal agent: erythema multiforme (five patients), erythroderma (one), severe urticaria (one), pityriasis rosea (one) and worsening of pre-existing psoriasis (two patients). The spectrum of cutaneous adverse effects associated with terbinafine therapy is reviewed. Patients should be counselled about discontinuing terbinafine at the onset of a cutaneous eruption and about seeking medical advice about further management.

The spectrum of cutaneous reactions associated with diltiazem: three cases and a review of the literature

BACKGROUND

Cutaneous reactions ranging from exanthems to severe adverse events have been reported in association with calcium channel blockers.

OBJECTIVE

Our purpose was to document cutaneous eruptions resulting from use of diltiazem.

METHODS

We describe three patients who experienced a cutaneous reaction (i.e., hypersensitivity syndrome reaction, pruritic exanthematous eruption, and acute generalized exanthematous pustulosis) possibly induced by diltiazem, summarize adverse reaction reports obtained from the Health Protection Branch, and review the literature on calcium channel blockers inducing cutaneous reactions.

RESULTS

Of the 315 cases of possible diltiazem-induced adverse reactions that were reported to the Health Protection Branch, 151 (48%) were cutaneous. The number of diltiazem-induced cutaneous events was significantly greater than those induced by either nifedipine or verapamil. However, no difference was found in the proportion of serious cutaneous adverse events to either of the three drugs.

CONCLUSION

Diltiazem has been associated with a variety of cutaneous reactions that appear to occur more frequently than with other calcium channel blockers.

Pharmacoeconomic analysis of topical treatments for tinea infections

BACKGROUND

A payor-perspective economic analysis of the topical creams ciclopirox, clotrimazole, ketoconazole, miconazole, and terbinafine (TER) used to treat dermatophytosis has been made. This pharmacoeconomic evaluation was conducted in Austria, Germany, and Switzerland.

METHODS

A four-phase approach was used. Phase 1: experts were assembled to identify the standard approach for management of fungal infections and a decision tree was constructed to model the process. Phase 2: meta-analysis was used to determine success, failure, and relapse rates. Phase 3: economic analyses performed included cost of regimen, total expected cost, and cost-effectiveness. Phase 4: sensitivity analyses (robustness analysis) were also executed to determine the validity of the assumptions.

RESULTS

In the total expected cost analysis, TER demonstrated the lowest overall cost of treating patients. Terbinafine also provided the highest number of disease-free days during the analytic time horizon and, consequently, the lowest cost per disease-free day. Sensitivity analyses suggest that TER is the most cost-effective topical product for treating dermatophytosis in Austria, Germany, and Switzerland.

CONCLUSIONS

All analytic scenarios suggest that TER therapy demonstrates lower expected costs and generates more DFDs when compared with the fungistatic topical therapies included in this pharmacoeconomic analysis. Terbinafine is expected to be the most cost-effective choice in Austria, Germany, and Switzerland for treatment of dermatophytosis minor.

Terbinafine: an update

Oral terbinafine was first introduced in the United Kingdom in February 1991 and was approved for the treatment of onychomycosis in the United States in May 1996. It is estimated that 4 million patients worldwide have been treated with oral terbinafine as of December 1996. The efficacy of terbinafine in the treatment of onychomycosis and other dermatomycoses is reviewed. The adverse-effects profile of oral terbinafine is evaluated.

The efficacy, safety and tolerability of antidepressants in late life depression: a meta-analysis

BACKGROUND

To determine the efficacy, safety and tolerability of antidepressants in depressed elderly patients.

METHODS

Search for randomized controlled double-blind studies evaluating atypical antidepressants (ATYPs), reversible inhibitors of monoamine oxidase-A, selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants in moderate/severe depressed patients > or = 60 years for > or = four weeks. The random effects model (single-arm; comparative) was used to aggregate efficacy, safety and dropout.

RESULTS

No difference in single-arm aggregation of outcomes for four antidepressant classes. Comparative analyses showed no statistical difference between outcomes, except SSRIs had a higher response rate than ATYPs.

CONCLUSION

Elderly show no differences in antidepressant class outcomes.

LIMITATIONS

Heterogeneity and lack of power.

CLINICAL RELEVANCE

There is little advantage for antidepressant classes over another in the aged.

Cytochrome P-450 3A: interactions with dermatologic therapies

Recent case reports and studies suggest that interactions involving the cytochrome P-450 mixed function oxidase system are important causes of medication toxicity and decreased efficacy during combination drug therapy. The cytochrome P-450 3A3/4 isoenzyme is involved in many significant drug interactions. New and familiar drugs continue to be implicated as having potentially serious interactions with this group of enzymes. An understanding of the basic principles of these interactions may have a major impact on patient outcome.

Oral terbinafine in the treatment of toenail onychomycosis: North American multicenter trial

BACKGROUND

Onychomycosis is an increasing problem with limited therapeutic options.

OBJECTIVE

We evaluated the safety and efficacy, of oral terbinafine, a new fungicidal antimycotic, in patients with toenail onychomycosis.

METHODS

A North American multicenter, double-blind, placebo-controlled study evaluated the mycologic and clinical efficacy of oral terbinafine 250 mg/day for 12 or 24 weeks in 358 patients with toenail onychomycosis.

RESULTS

A total of 74% of patients treated with 12 or 24 weeks of terbinafine achieved a successful clinical outcome. Approximately 11% of terbinafine responders showed evidence of relapse 18 of 21 months after cessation of treatment. Terbinafine was well tolerated; most adverse events were transient and mild to moderate in severity.

CONCLUSION

The results of this study confirm that oral terbinafine is a safe and effective therapy for the treatment of onychomycosis.

Drug interactions in human neuropathic pain pharmacotherapy

Current practice predicates the use of multiple drug combinations in the treatment of neuropathic pain. These combinations may be required because of multiple pain symptoms directly arising from neuropathic pathology, other symptoms attributable to the chronicity and severity of the patient's pain or conditions unrelated to their pain. A fear exists that combination drug use or the addition of a new drug to a therapeutic regimen may lead to increased drug toxicity or decreased efficacy. Many of the drug interactions of significance to neuropathic pain physicians involve the cytochromes P450 2D6 and 3A3/4 isoenzymes. Drug interactions should be more predictable based on the knowledge of which compounds induce, inhibit or are metabolized by specific cytochrome P450 enzymes. Mechanisms of induction or inhibition of biotransformation via the P450 hepatic enzyme system are discussed and various inducers, inhibitors and substrates relating to neuropathic pain pharmacotherapy are listed.

Comparative safety of tetracycline, minocycline, and doxycycline

BACKGROUND

Because minocycline can cause serious adverse events including hypersensitivity syndrome reaction (HSR), serum sicknesslike reaction (SSLR), and drug-induced lupus, a follow-up study based on a retrospective review of our Drug Safety Clinic and the Health Protection Branch databases and a literature review was conducted to determine if similar rare events are associated with tetracycline and doxycycline. Cases of isolated single organ dysfunction (SOD) attributable to the use of these antibiotics also were identified.

OBSERVATIONS

Nineteen cases of HSR due to minocycline, 2 due to tetracycline, and 1 due to doxycycline were identified. Eleven cases of SSLR due to minocycline, 3 due to tetracycline, and 2 due to doxycycline were identified. All 33 cases of drug-induced lupus were attributable to minocycline. Forty cases of SOD from minocycline, 37 cases from tetracycline, and 6 from doxycycline were detected. Hypersensitivity syndrome reaction, SSLR, and SOD occur on average within 4 weeks of therapy, whereas minocycline-induced lupus occurs on average 2 years after the initiation of therapy.

CONCLUSIONS

Early serious events occurring during the course of tetracycline antibiotic treatment include HSR, SSLR, and SOD. Drug-induced lupus, which occurs late in the course of therapy, is reported only with minocycline. We theorize that minocycline metabolism may account for the increased frequency of serious adverse events with this drug.

Multivesicular stellate cells in primary biliary cirrhosis

Stellate cells have only recently received attention in patients with primary biliary cirrhosis (PBC). We used electron microscopy and morphometry to perform a qualitative and quantitative examination of lipid-storing activity of stellate cells in liver biopsies of 26 patients with noncirrhotic and cirrhotic PBC. Parallel with this study, a comparative analysis of the morphology of stellate cells in 51 patients with livers of normal histology was performed. There was a marked increase in the total number of lipid vesicles in stellate cells in all PBC patients when compared to livers with normal histology. Multiple multivesicular stellate cells were seen in the livers of 21 out of 26 patients with PBC. There were 11 to 28 lipid vesicles per multivesicular stellate cell from 1 micromol/L to 5 micromol/L in diameter per lipid vesicle. Hepatocytes showed little or no steatosis in 24 out of 26 (92%) PBC patients. Multivesicular stellate cells were not seen in female patients with normal liver histology. These results suggest that there is an alteration in hepatic lipid-storage that involves stellate cells in PBC, which could be an early manifestation of this disease. Its significance remains to be determined.

Serious dermatologic reactions in children

Although serious reactions comprise only a small percentage of total adverse drug reactions, they are important in terms of morbidity and potential mortality. An update on serious dermatologic reactions in children is presented including serum sickness-like reactions due to cefaclor, hypersensitivity syndrome reactions (HSRs), and drug-induced pseudoporphyria. More detailed information on minocycline-induced reactions including drug-induced lupus and HSRs and lamotrigine-induced toxic epidermal necrolysis and Stevens-Johnson syndrome will be discussed.