Second- and third-generation antihistamines in the treatment of urticaria

ABSTRACT: Chronic urticaria is mainly idiopathic in nature and can be difficult to treat. While less responsive to antihistamine therapy than acute urticaria, antihistamines still play a key role in the management of symptomatology. While many of the antihistamines still commonly used to treat urticaria are first generation H₁ antagonists (e.g., diphenhydramine, hydroxyzine), the more recently developed second-generation agents (e.g., loratadine, cetirizine) and their metabolites—the third-generation antihistamines (e.g., fexofenadine, norastemizole, descarboxyloratadine)—possess many of the desirable clinical effects of the first-generation agents with a more tolerable side effect profile. This review discusses the advantages and disadvantages of each of the various second- and third-generation agents available, and presents some of the data showing the differences among these agents in the treatment of chronic urticaria.     

Comparison of the potency of antihistamines

ABSTRACT: First- and second-generation antihistamines have proven effective in the management of patients with urticaria and allergic rhinitis; however, the efficacy of first-generation antihistamines has been compromised by undesirable side effects such as sedation, dry mouth, and blurred vision. Second-generation antihistamines, on the other hand, are less sedating and have fewer side effects than first-generation agents. Recently second-generation agents have been compared for their pharmacologic activities using an epicutaneous histamine-induced wheal and flare model in normal volunteers. Cetirizine was found to be superior to epinastine, ebastine, fexofenadine, terfenadine, loratadine, and placebo in inhibiting the wheal and flare response. Epinastine had the fastest onset of action at 30 minutes and terfenadine proved to be superior to its metabolite fexofenadine.     

Review of H1 antihistamines in the treatment of chronic idiopathic urticaria

Chronic idiopathic urticaria (CIU) can have a profound effect on patient quality of life (QOL). Ideally, any therapy used to treat CIU should be effective across a wide range of doses without causing unwanted side effects; a wide therapeutic window allows the physician to tailor treatment to the individual. Oral H1 antihistamines are the mainstay of therapy for CIU, but agents within this class diverge in their individual therapeutic indices. The literature was reviewed to compare the currently available oral H1 antihistamines regarding their efficacy and safety at a wide range of doses. If sedation and cognitive impairment are considered relevant to treatment selection due to their effect on QOL and safety, then newer-generation agents should be selected over older-generation antihistamines. There are few well-controlled clinical studies in which newer-generation agents have been directly compared. Moreover, there are no evidence-based data demonstrating statistical superiority of one newer-generation agent over another in the treatment of CIU. However, of the newer agents, those that are labelled nonsedating at recommended doses (fexofenadine, loratadine, and desloratadine) should be selected over cetirizine. In cases where the physician judges that a higher-than-recommended dose should be prescribed, or when the patient is likely to take a higher dose, the relative safety profile of these agents demands detailed consideration.     

Pharmacological rationale for the treatment of chronic urticaria with second‐generation non‐sedating antihistamines at higher‐than‐standard doses

Chronic urticaria (CU) is a long‐lasting and distressing condition that impairs patient quality of life (QoL) by disrupting sleep and diminishing work/school productivity. Thus treatment should not only be safe and effective but also not add to this impairment or increase risks to health or safety. Non‐sedating second‐generation antihistamines, with their long duration of action, pharmacodynamic properties that allow once‐daily dosing and lack of drug–drug interactions and sedative effects, are the first‐line symptomatic treatment option, but some patients have no adequate response to standard doses of these medications. Other therapeutic approaches to refractory urticaria have been suggested but have been limited by sparse clinical data and/or significant adverse effect profiles. Although discouraged by treatment guidelines, sedating antihistamines are frequently prescribed for nighttime use when urticaria symptoms are severe as add‐on therapy to a non‐sedating antihistamine. However, their pronounced effects on rapid eye movement sleep and hangover negatively impact QoL, learning and performance, and limit their use for patients in occupations that require alertness. For patients who do not respond adequately to standard doses of non‐sedating second‐generation antihistamines, increasing the dose of non‐sedating antihistamines thus may represent the safest therapeutic approach. Given the fact that only few controlled studies have assessed the efficacy and safety of high‐dose non‐sedating antihistamines in CU, patient safety should be a key consideration when choosing a specific antihistamine.     

Treatment of Urticaria

Urticaria is a cutaneous syndrome characterized by dermal edema (wheal) and erythema (flare) that blanches with pressure. The lesions typically last less than 24 hours and are usually pruritic. In 1983, Christensen and Maibach summarized the theory behind the use of histamine H₁ receptor antagonists (antihistamines) in clinical dermatology. These agents remain the mainstay of treatment for urticaria. This article reviews the medical literature on the effectiveness of antihistamines in urticarial syndromes, including acute, chronic idiopathic and the physical urticarias. Older antihistamines, such as chlorpheniramine and hydroxyzine, are effective in the treatment of urticarias, but they also have marked sedative and anticholinergic effects. Newer nonsedating antihistamines (second-generation antihistamines) have been developed that have reduced adverse effects because they do not cross the blood-brain barrier; these agents (acrivastine, cetirizine, loratadine, mizolastine, fexofenadine, ebastine, azelastine and epinastine) cause significantly less sedation and psychomotor impairment than their older counterparts. A review of the literature reveals that there are few studies which document the efficacy of second-generation antihistamines in the treatment of acute urticaria, a biologic entity that usually resolves within 3 weeks. We did not identify controlled studies that suggested superiority of any antihistamine in the treatment of acute urticaria. Loratadine or cetirizine, and possibly mizolastine, appear to be treatments of choice for chronic idiopathic urticaria. For symptomatic dermatographism, the combination of an antihistamine and an H₂ antagonist, e.g. chlorpheniramine and cimetidine, appears to be effective. Very few studies have been conducted on the use of antihistamines in the treatment of cold, cholinergic, and pressure urticaria. Antihistamines are the mainstay of urticarial therapy. This evidence-based review suggests that there are efficacy differences between newer, nonsedating antihistamines and older agents in some forms of the disorder. Clearly, further well-controlled clinical trials in larger numbers of patients are needed to clarify the role of these agents in the treatment of urticaria.     

Topical Retinoids in Acne Vulgaris

Topical retinoids represent a mainstay of acne treatment because they expel mature comedones, reduce microcomedone formation, and exert anti-inflammatory effects. The first-generation retinoid tretinoin (all-trans retinoic acid) and the synthetic third-generation polyaromatics adapalene and tazarotene are approved for acne treatment by the US FDA, whereas topical tretinoin, isotretinoin (13-cis retinoic acid), and adapalene are accredited in Canada and Europe. Topical retinoids have a favorable safety profile distinct from the toxicity of their systemic counterparts. Local adverse effects, including erythema, dryness, itching, and stinging, occur frequently during the early treatment phase. Their impact varies with the vehicle formation, skin type, frequency and mode of application, use of moisturizers, and environmental factors such as sun exposure or temperature. The broad anti-acne activity and safety profile of topical retinoids justifies their use as first-line treatment in most types of non-inflammatory and inflammatory acne. They are also suitable as long-term medications, with no risk of inducing bacterial resistance, for maintenance of remission after cessation of initial combination therapy.     

Desloratidine for the treatment of chronic urticaria

Chronic urticaria is a common dermatologic condition that is idiopathic in most cases. Antihistamines are the mainstays of treatment for this condition. The newer, second and third generation antihistamines are the preferred agents because of their improved safety profile and comparable efficacy to the first generation antihistamines. Desloratadine is a new non-sedating H1-receptor agonist. Based on clinical studies, desloratadine is a valuable new addition to the available treatment options and should be considered as a first-line therapy for patients with chronic urticaria.     

The urticaria spectrum: recognition of clinical patterns can help management

Urticaria has diverse clinical presentations and causes. The implication of classifying urticaria primarily by clinical presentation rather than aetiology is that management can be focused on specific clinical problems without extensive investigations. Management pathways may involve nonpharmacological measures and drug interventions, which can be grouped into first-, second- and third-line therapies. Stronger, but potentially more risky, second- and third-line approaches may be justified for patients who do not respond to first-line therapy with antihistamines even though it may not be possible to define a specific aetiology, such as autoimmune urticaria, with confidence.     

Effects of single therapeutic doses of promethazine, fexofenadine and olopatadine on psychomotor function and histamine-induced wheal- and flare-responses: a randomized double-blind, placebo-controlled study in healthy volunteers

Since most first-generation antihistamines have undesirable sedative effects on the central nervous systems (CNS), newer (second-generation) antihistamines have been developed to improve patients’ quality of life. However, there are few reports that directly compare the antihistaminic efficacy and impairment of psychomotor functions. We designed a double-blind, placebo controlled, crossover study to concurrently compare the clinical effectiveness of promethazine, a first-generation antihistamine, and fexofenadine and olopatadine, second-generation antihistamines, by measuring their potency as peripheral inhibitors of histamine-induced wheal and flare. Further, we investigated their sedative effects on the CNS using a battery of psychomotor tests. When single therapeutic doses of fexofenadine (60 mg), olopatadine (5 mg) and promethazine (25 mg) were given in a double-blind manner to 24 healthy volunteers, all antihistamines produced a significant reduction in the wheal and flare responses induced by histamine. In the comparison among antihistamines, olopatadine showed a rapid inhibitory effect compared with fexofenadine and promethazine, and had a potent effect compared with promethazine. In a battery of psychomotor assessments using critical flicker fusion, choice reaction time, compensatory tracking, rapid visual information processing and a line analogue rating scale as a subjective assessment of sedation, promethazine significantly impaired psychomotor function. Fexofenadine and olopatadine had no significant effect in any of the psychomotor tests. Promethazine, fexofenadine and olopatadine did not affect behavioral activity, as measured by wrist actigraphy. These results suggest that olopatadine at a therapeutic dose has greater antihistaminergic activity than promethazine, and olopatadine and fexofenadine did not cause cognitive or psychomotor impairment.     

Antihistamines and their role as antipruritics

Antihistamines that bind to the histamine 1 receptor (H1) serve as important therapeutic agents to counter the effects of histamine in the skin. Two generations of antihistamines exist; however, second-generation agents are more advantageous because they cause less sedation, have a longer half life and are more selective for the H1 receptor. While H1 antihistamines have proven to be effective at reversing the pruritus and cutaneous lesions of chronic urticaria, their ability to treat pruritus associated with other cutaneous and systemic diseases is unproven.     

Erlotinib-induced florid acneiform rash complicated by extensive impetiginization

Erlotinib (Tarceva) is an epidermal growth factor receptor (EGFR) inhibitor, a member of a new group of molecular targeted drugs that combine high efficacy against tumours with less, often self-limiting, toxicity, compared with traditional chemotherapeutics. It is used for treatment of solid-organ tumours, especially as second- or third-line therapy for non-small-cell lung cancer. Dose-related cutaneous side-effects and diarrhoea may be a significant obstacle to treatment compliance. We present two cases with long-lasting acneiform eruptions, complicated by significant impetiginization, resulting in hospitalization in one case. The other patient suffered from sleep-disturbing, itching crusts on the scalp. As the use of EGFR inhibitors is increasing, clinicians should be aware of their side-effects. Early and timely dermatological intervention may diminish adverse events for patients treated with these agents and improve quality of life.     

Antihistamines

In the 1990s, major improvements occurred in the therapeutic index of H1 antihistamines. The third-generation compounds promise to be more effective and nontoxic. The future major advances are likely to result from development and exploitation of non-H1 receptor-mediated antiallergic actions of these drugs.     

Pediculosis and the Pediatrician

Head lice commonly evoke feelings of disgust, revulsion, anger, and shame among parents and patients. There should, however, be no great cause for such alarm if a physician suspects pediculosis capitis. The recent introduction of several new pediculicidal drugs now allows a choice among four distinct therapeutic agents, which should substantially improve control of isolated cases and epidemics. Physicians must be aware that consumer groups are pressing public health authorities and drug manufacturers to establish proper treatment standards and safety warnings for the use of these agents. In addition, some controversy surrounds the use of lindane in children. This paper reviews the epidemiology and clinical appearance of pediculosis capitis in children, with emphasis on these recent developments. Pubic lice (Phthirus pubis) and body lice (Pediculus humanus corporis), both of which are much less common pediatric infestations, are mentioned only briefly.     

Etanercept for psoriasis in the pediatric population: experience in nine patients

Psoriasis commonly affects children and adolescents, and the need for safe, effective therapy is a special consideration in the pediatric population. In recent years, the use of targeted immunomodulatory biologic agents has been increasingly studied for the treatment of psoriasis. Of these, etanercept, a tumor necrosis factor-alpha antagonist, has been approved for the treatment of psoriasis and psoriatic arthritis in adults, and while it is approved for use in juvenile rheumatoid arthritis, formal studies are needed to demonstrate its safety and efficacy for childhood psoriasis. We present our preliminary experience of treating nine pediatric patients with generalized, recalcitrant psoriasis with etanercept therapy.     

An evidence-based review of the efficacy of antihistamines in relieving pruritus in atopic dermatitis

OBJECTIVE: To critically review the body of clinical trials that refute or support the efficacy of antihistamines in relieving pruritus in patients with atopic dermatitis. DESIGN: Review of MEDLINE from 1966 through March 1999, the Cochrane Database of Systematic Reviews, and Best Evidence to identify therapeutic trials of antihistamines in patients with atopic dermatitis. MAIN OUTCOME MEASURES: All randomized controlled trials or clinical trials of antihistamines used in the treatment of atopic dermatitis. We found 16 studies throughout the literature. RESULTS: Large, randomized, double-blind, placebo-controlled clinical trials with definitive conclusions (grade A trials) have not been performed. Two grade B trials (small, rigorous, randomized trials with uncertain results due to moderate to high alpha or beta error) refuted the use of antihistamines in relieving pruritus. One grade B trial supported the efficacy of antihistamines in relieving pruritus. All remaining trials (grade C) lacked placebo controls or randomization, or contained fewer than 20 patients in each treatment group. CONCLUSIONS: Although antihistamines are often used in the treatment of atopic dermatitis, little objective evidence exists to demonstrate relief of pruritus. The majority of trials are flawed in terms of the sample size or study design. Based on the literature alone, the efficacy of antihistamines remains to be adequately investigated. Anecdotally, sedating antihistamines have sometimes been useful by virtue of their soporific effect and bedtime use may be warranted. There is no evidence to support the effectiveness of expensive nonsedating agents.     

Transition from methotrexate and cyclosporine to other therapies including retinoids, ultraviolet light and biologic agents in the management of patients with psoriasis

Patients with psoriasis typically face longterm therapy for their chronic disease. Often, the therapeutic agents that physicians use to treat them may become less effective or may cause safety or toxicity issues. The clinician must then decide the next therapy for his/her patient and assess benefit/risk of the next therapeutic agent or combination. In moving the patient from one therapy to the next, specific characteristics of the transition must be assessed, and how to stop the existing therapy, and introduce the new agent(s). The decision making process must take into account the longterm risks to the patient. This article focuses on the transition for patients with psoriasis being managed with methotrexate and cyclosporine to retinoids, phototherapy, and newer agents.     

Labeled use of efinaconazole topical solution 10% in treating onychomycosis in children and a review of the management of pediatric onychomycosis

Onychomycosis is a difficult to treat condition whose prevalence is increasing. Until recently, there was no FDA approved antifungal agent for the treatment of onychomycosis in children. Although systemic antifungal agents are effective, their use is restricted by the potential adverse events and drug‐drug interactions. There is evidence regarding the safety and efficacy of topical antifungal agents for pediatric onychomycosis. We have summarized the results of a recently published study using efinaconazole topical solution 10% to treat onychomycosis in children and discuss management of pediatric onychomycosis. In a multicenter, open‐label phase 4 study, efinaconazole 10% solution was applied topically once daily in children aged 6 to 16 years with mild to severe, culture positive, distal and lateral subungual onychomycosis. Treatment was for 48 weeks with a follow‐up at week 52. Pharmacokinetics was performed in a subset of patients. There were 62 patients enrolled in the study. At week 52, the efficacy was mycological cure rate 65% and complete cure rate 40%. All treatment‐emergent adverse events (TEAE) were mild to moderate in severity with none resulting in study discontinuation. The only treatment‐related TEAE was ingrown toenail. Efinaconazole was detected at low levels in plasma. Efinaconazole topical solution 10% is effective and safe in treating onychomycosis in children age 6 to 16 years and was recently FDA‐approved for this indication. The on‐label use of other topical agents, tavaborole solution 5% and ciclopirox nail lacquer solution 8% is reviewed. We also briefly discuss the use of oral agents, terbinafine, itraconazole, and fluconazole in pediatric onychomycosis.     

皮肤肥大细胞瘤6例病例报道及文献复习

目的了解儿童皮肤肥大细胞瘤的临床特点。方法收集诊治的6例儿童皮肤肥大细胞瘤的临床资料,并复习近年来国内文献报道的资料完整的14例病例,分析疾病的临床表现、治疗及随访情况。结果共20例,男7例,女13例,平均年龄(11.7±8.6)个月,平均病程(9.3±6.7)个月。65%的患者出生时即有皮疹。皮损多为单发,以躯干为主。治疗多采取抗组胺药、糖皮质激素或手术切除。10例患儿随访2~60个月,皮损均有一定程度减退,局部遗留色素沉着或色素减退斑。结论肥大细胞瘤主要发生于婴幼儿,通常2岁以前发病,皮疹多为单发,好发于躯干,预后良好。     

Tacrolimus ointment: utilization patterns in children under age 2 years

Atopic dermatitis (AD) is a common eczematous skin condition; as many as 10-17 percent of all children are affected, and 35-60 percent of affected patients manifest symptoms manifest during the first year of life. Treatment principles for AD in young children involve conservative measures such as avoidance of hot water and environmental irritants, combined with liberal use of emollients after bathing. Low potency topical corticosteroids (TCS) are the current standard of therapy for AD in young children, reserving mid- and high-potency TCS for severe disease. However, complications of long-term use of TCS include skin atrophy, stria formation, telangiectasia, hypopigmentation, secondary infections, steroid acne, allergic contact dermatitis, and miliaria. The pediatric population is also at increased risk for systemic absorption because of their high ratio of skin surface to body mass. Systemic absorption may result in hypothalamic-pituitary-adrenal axis suppression and ultimately growth retardation. Although most topical and systemic corticosteroids are not approved by the Food and Drug Administration for use in children less than 2 years of age, conservative treatment often fails in this age group and frequently patients are treated with TCS, antibiotics, and antihistamines.