Effect of coadministration of corticosteroids on the development of contact sensitization

Transdermal rivastigmine: management of cutaneous adverse events and review of the literature

Alzheimer's disease is a chronic neurodegenerative disorder resulting in part from the degeneration of cholinergic neurons in the brain. Rivastigmine, a cholinesterase inhibitor, is commonly used as a treatment for dementia due to its ability to moderate cholinergic neurotransmission; however, treatment with oral rivastigmine can lead to gastrointestinal adverse effects such as nausea and vomiting. Transdermal administration of rivastigmine can minimize these adverse effects by providing continuous delivery of the medication, while maintaining the effectiveness of the oral treatment. While the transdermal form of rivastigmine has been found to have fewer systemic adverse effects compared with the oral form, cutaneous reactions, such as contact dermatitis, can lead to discontinuation of the drug in its transdermal form. Lack of patient compliance with regard to applying the patch to the designated site, applying the patch for the correct length of time or rotating patch application sites increases the risk of cutaneous adverse reactions. This article outlines the diagnosis and management of irritant contact dermatitis and allergic contact dermatitis secondary to transdermal rivastigmine. The large majority of reactions to transdermal patches are of an irritant type, which can be diagnosed clinically by the presence of a pruritic, erythematous, eczematous plaque strictly confined to the borders of the patch. In contrast, an allergic reaction can be differentiated by the presence of vesicles and/or oedema, erythema beyond the boundaries of the transdermal patch and lack of improvement of the lesion 48 hours after removal of the offending treatment. By encouraging the patient to follow a regular rotation schedule for the patch, and using lipid-based emollients for irritant dermatitis and pre- and post-treatment topical corticosteroids for allergic dermatitis, cutaneous reactions can often be alleviated and patients can continue with their medication regimen. Other simple changes to a patient's treatment routine, including minimizing the use of harsh soaps, avoiding recently shaven or damaged areas of skin and carefully removing the patch after use, can help to further decrease the risk of dermatitis development.

Challenges and opportunities in dermal/transdermal delivery

Transdermal drug delivery is an exciting and challenging area. There are numerous transdermal delivery systems currently available on the market. However, the transdermal market still remains limited to a narrow range of drugs. Further advances in transdermal delivery depend on the ability to overcome the challenges faced regarding the permeation and skin irritation of the drug molecules. Emergence of novel techniques for skin permeation enhancement and development of methods to lessen skin irritation would widen the transdermal market for hydrophilic compounds, macromolecules and conventional drugs for new therapeutic indications. As evident from the ongoing clinical trials of a wide variety of drugs for various clinical conditions, there is a great future for transdermal delivery of drugs.

Rivastigmine transdermal system for the treatment of mild to moderate Alzheimer's disease

Today patients with mild to moderate Alzhiemer's disease (AD) have a treatment approach choice: oral or transdermal delivery. The aim of this review was to provide a concise, comprehensive overview of the clinically relevant safety, tolerability and efficacy information available for the rivastigmine transdermal system. Relevant articles were identified through a MEDLINE search of publications in the past 3 years using the terms 'rivastigmine' and 'transdermal' or 'patch'. Efficacy, safety and tolerability of the rivastigmine patch vs. placebo were established in a large, international, 24-week, double-blind, randomised clinical trial and subsequent 28-week open-label extension study. Drug exposure with the 9.5 mg/24 h rivastigmine patch was not significantly different to that provided by an oral capsule dose of 12 mg/day. Most frequently observed adverse events were gastrointestinal. In the primary study, incidences of nausea, vomiting and diarrhoea were: 5%, 3% and 3% respectively in the placebo group; 7%, 6% and 6% in the 9.5 mg/24 h rivastigmine patch group; and 23%, 17% and 5% in the 12 mg/day capsule group. Most patients experienced no, slight or mild application-site skin reactions. De novo patients or those taking oral rivastigmine or donepezil may tolerate a switch to rivastigmine patch. By providing drug exposure that is not significantly different to the highest recommended rivastigmine capsule dose (12 mg/day), with less fluctuation over 24 h, rivastigmine patch offers similar efficacy with an improved tolerability profile. The rivastigmine patch provides a viable treatment option for patients with mild to moderate AD.

Skin tolerability associated with transdermal drug delivery systems: an overview

As transdermal patches become more widely prescribed, it is important that clinicians understand: (a) the common causes of skin reactions with these medications; (b) how to minimize these reactions; and (c) how to manage the signs and symptoms. Here we review published data for skin reactions with patch medications approved within the past decade. Overall, the most common application site signs and symptoms appear to be localized redness (erythema) or itching, sometimes accompanied by swelling (edema). Typically, these are mild to moderate in severity, transient in nature, and occur in 20% to 50% of patients. Most are localized to the area of application, and resolve spontaneously within several days following patch removal. Discontinuations due to these types of event are infrequent, ranging from 1.7% to 6.8% in the 6-month trials reviewed here. Based on expert opinion, the majority of these skin reactions would be a form of irritant contact dermatitis, with infrequent cases of allergic contact dermatitis. These types of reactions usually cause minimal pain or discomfort to the patient, and are unlikely to be of medical concern. Signs and symptoms of irritant contact dermatitis may be minimized by rotation of the application site, careful removal of the patch, and appropriate use of moisturizers and topical corticosteroids. In conclusion, the potential advantages of transdermal patches usually outweigh any additional skin issues; however, further research into treatment and management strategies is required.

Cutaneous Reactions to Transdermal Therapeutic Systems

Transdermal therapeutic systems have been increasingly used in the past two decades. However, cutaneous side effects are fairly common and may result in poor patient compliance. This review article summarizes the spectrum of reactions due to transdermal therapeutic systems and provides a current list of known allergens.

Transdermal drug delivery systems and skin sensitivity reactions. Incidence and management

Transdermal devices are now marketed for the delivery of systemic medication through the skin. Advantages associated with transdermal drug delivery include avoidance of first-pass metabolism and variable absorption as well as improved patient compliance. Drugs currently available by this route include scopolamine, nitroglycerin (glyceryl trinitrate), estradiol, nicotine, clonidine, fentanyl, and testosterone. This novel development has brought about a specific constellation of skin problems which vary widely in incidence between drugs. It is important to vary the site of drug administration to minimize these reactions. Any eczematous reaction can be treated with a moderately potent topical corticosteroid. Patients with topical sensitivity are usually tolerant of oral challenge but systemic sensitization has been reported and caution is still advocated before proceeding to this step. The increasing use of transdermal drug delivery systems across many specialities means that problems of skin sensitivity are of growing relevance to the dermatologist, the hospital specialist, and the primary care physician.

Use of topical corticosteroid pretreatment to reduce the incidence and severity of skin reactions associated with testosterone transdermal therapy

Local skin reactions at the application site are the most common adverse events associated with the testosterone transdermal delivery (TTD) systems used to treat postpubertal hypogonadism in males. This open-label, controlled pilot study was conducted to determine whether topical pretreatment with triamcinolone acetonide 0.1% cream might be useful in reducing the incidence and/or severity of chronic skin irritation when used in healthy volunteers receiving TTD systems. Adult male volunteers wore three topical systems, which were applied to the upper back daily (Monday through Friday) for 6 weeks: (1) TTD with no pretreatment of application site; (2) TTD with pretreatment of application site using triamcinolone acetonide 0.1% cream; and (3) an inactive occlusive dressing (control). On Monday through Thursday, systems were removed 24 hours after application. Patches applied on Friday were worn continuously for 72 hours until their removal on Monday. Skin reactions were graded on a scale from 0 to 4 (0 = none, 4 = severe) and were assessed daily by research personnel, beginning at the time of system removal (assessment 1) and on the two subsequent clinic visits (assessments 2 and 3). All skin irritation scores of all subjects were totaled for each treatment regimen to obtain a cumulative score per treatment regimen. The cumulative scores were also analyzed by assessment time and study week (weeks 1-6). Eighty-two subjects were enrolled in the study, and 65 completed the 6-week treatment course. Mean age of subjects was 24 years (range, 18-69 years), and mean weight was 79.0 kg (range, 58.9-127.3 kg). All subjects were white males. At assessment 1, pretreatment with triamcinolone acetonide 0.1% cream (compared with no pretreatment) was associated more often with scores of 0 (no erythema), with comparable occurrences of mild skin irritation, and with fewer occurrences of moderate erythema. At all three assessments, more subjects had lower cumulative scores with pretreatment than without pretreatment. At every assessment and in each week of the study, total weekly cumulative skin irritation scores were also lower with pretreatment than without pretreatment. No adverse experiences other than skin irritation were reported. Results of this study suggest that in patients using TTD systems, the incidence and severity of skin irritation at application sites may be reduced through pretreatment with triamcinolone acetonide 0.1% cream.