Onychomycosis for Pharmacists: Part 1, Overcoming Common Misconceptions About Onychomycosis Post-test/Rationale

1. How common is onychomycosis? A. 1 in 10 persons*** B. 1 in 25 persons C. 1 in 50 persons D. 1 in 100 persons Correct Answer: A As described in this activity, 1 in 10 persons are affected by onychomycosis. This estimate is for the general population of the United States and varies greatly depending on specific demographics, such as age. For example, it is estimated that 25% of the population older than 70 years of age in certain regions may be affected.

2. What is the most common causative organism of onychomycosis? A. Dermatophytes*** B. Candida species C. Histoplasma species D. All of the above Correct Answer: A Dermatophytes comprise the majority of onychomycosis infections. It is estimated that these organisms are prevalent in approximately 68% of cases. Other organisms, such as yeast and non-dermatophyte molds, are contributors to the disease, but at much lower rates than dermatophytes.

3. Onychomycosis can cause which of the following: A. Painful toes B. Embarrassment C. Avoidance of social situations D. All of the above*** Correct Answer: D In addition to having physician complaints (discoloration and pain), onychomycosis may cause substantial psychological and social distress, including embarrassment, avoidance of social situations, negative self-esteem, and may even affect relationships. This may be because of the long-term nature of the disease and stigma associated with fungal infections within the general population.

4. Which of the following is a potential risk factor for onychomycosis: A. Use of nail polish B. Female gender C. Alcohol use D. Diabetes*** Correct Answer: D It is estimated one-third of patients with diabetes are affected by onychomycosis. This represents a substantial morbidity burden to this population and is of great concern because of the potential complications. Patients with diabetes may be prone to this infection because of poor vascularization. Nail polish is not associated with higher risk, nor is alcohol use. Infection rates are higher for men. 5. A woman, 34 years of age, asks which over-the-counter (OTC) product would be best for her thickened, discolored toenails. Which of the following is the most correct response: A. OTC terbinafine cream applied daily for 12 weeks B. OTC clotrimazole powder used daily for 48 weeks C. Tea tree oil applied twice daily for 6 months D. None of the above products, the patient should be referred to her health care provider***

Correct Answer: D OTC products have not been shown to be effective for treating onychomycosis to date. Patients should be referred to their primary care provider to be assessed for need of prescription therapy. This is especially important for patients from high-risk populations, such as older adults and those with diabetes. 6. A man, 70 years of age, is picking up his usual insulin prescription and mentions that his toes are painful. Upon further questioning, you learn that he has been having trouble trimming his toenails because the nails are so thick. He seems reluctant to bother his physician with this trivial matter. Which of the following is the most correct response: A. The patient is correct, this issue can be managed by self-care B. The patient should try an OTC product for 12 weeks C. The patient should see his physician about his nails because of the risk for complications*** D. The patient should only see the physician if he is having difficulty walking Correct Answer: C Self-care and OTC products are not effective for the treatment of onychomycosis. Additionally, patients should be treated prior to developing complications or other physical conditions. Therefore, this patient should be referred to his primary care provider for adequate assessment and treatment recommendations. 7. A patient recently diagnosed with onychomycosis presents a prescription for terbinafine. The patient expresses concern about the cost and the potential for adverse effects from the medication and asks about using a topical treatment instead. Which of the following is TRUE: A. Topical antifungal treatments have as many adverse effects as oral antifungals B. Treatment duration is longer for oral antifungal medications C. The mycologic and complete cure rates for terbinafine are greater than the topical treatments*** D. Topical treatments only have a mycologic cure rate of about 10% Correct Answer: C Cure rates with oral agents are greater from clinical trials, although data comparing both routes are lacking. Topical agents produce cure rates between 5.5% and 53.4%; however, oral agents result in cure rates up to 79% for fingernails. Therefore, success is better with oral agents yet adverse effects may limit use. Treatment duration is longer for topical agents (24 to 48 weeks versus 12 to 24 weeks).

8. A patient brings in a new prescription for itraconazole 200 mg once daily for 12 weeks. You check the patient’s medication profile and notice that he is also taking sotalol and warfarin for atrial fibrillation. Which one of the following management options is most correct: A. Dispense the itraconazole because drug interactions are present B. Contact the prescriber to switch to terbinafine, which is less likely to interact with the patient’s medications*** C. Suggest that the prescriber switch to itraconazole pulse therapy to minimize adverse effects D. Recommend that the patient use terbinafine cream to save money Correct Answer: B Itraconazole is prone to many drug-drug interactions that can negatively alter the effectiveness of this drug and expose the patient to decreased efficacy or increased toxicity from the interacting agent. Terbinafine is much less prone to drug-drug interactions and maintains high cure rates. Therefore, the correct action is to contact the physician to have the drug changed.

9. A man, 24 years of age, is concerned with getting onychomycosis from his roommate. Which one of the following is TRUE: A. Onychomycosis cannot be spread to other household members B. This individual can help prevent fungal nail infections by not walking barefoot, especially in shared showers*** C. Because this individual does not have diabetes, he is not at risk for developing onychomycosis D. The patient is only at risk if he shares nail clippers with his roommate Correct Answer: B Prevention is the best strategy for this individual, especially wearing footwear in the shower; additionally, he should not share nail clippers. Other prevention strategies include keeping feet clean and dry and maintaining good hygiene. Although he is less at risk than an individual with diabetes, anyone can be infected even if not immunocompromised.

10. Which one of the following is a potential complication from onychomycosis: A. Diabetic foot syndrome B. Cellulitis C. Systemic fungal infection D. All of the above*** Correct Answer: D Although rare, all of the above serious infections can be complications of onychomycosis. These complications are more common for immunocompromised individuals or other high-risk groups (e.g., older adults and those with diabetes), but untreated infections will have the potential to spread and even result in secondary bacterial infections for everyone. This point underlines the importance of prompt and adequate treatment, in addition to counseling for prevention strategies. By doing so, most infections can be managed with minimal discomfort and risk for the patient.