Desensitization to methylphenidate – The relevance of continued drug intake for a successful outcome

Methylphenidate is the treatment of choice in attention-deficit / hyperactivity disorder (ADHD).The authors report the case of a 7 year old boy with ADHD and psoriasis who developed generalise derythema, pruritus and fever 5 hours after the first oral administration of methylphenidate. After 2 days of treatment the drug was discontinued with complete resolution of symptoms. Later on, the drug wasre-introduced with recurrence of the same clinical symptoms. Patch tests were performed with negative results. Desensitization was proposed and performed because there is no alternative treatment for ADHD. After the therapeutic dose was achieved, the mother interrupted drug intake because of a misunderstanding of instructions, and a mild rash subsided when another pill was administered. After this event the same desensitization procedure was carefully repeated. Interruption of drug intake during desensitization and consequent recurrence of clinical symptoms highlights the importance of continued exposure to the culprit drug in this kind of procedure.This modified protocol may enable patients with cutaneous reactions to this drug, to maintain therapy without recurrent reactions

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Allergic contact blepheroconjunctivitis with phenylephrine eyedrops ­the relevance of late readings of intradermal tests / Blefaroconjuntivitis alergica de contacto por colirio de fenilefrina. Relevancia de la lectura tardía de las pruebas intradermicas

Allergic reactions to midriatic eyedrops are rare despite extensively used by ophthalmologists. Phenylephrine is responsible for 54-95 % of cases reported in literature. We present the case of a 56-year-old man with blepharoconjunctivitis after instillation of phenylephrine 5 %, tropicamide 0.5 %, oxibuprocaine eyedrops. The patient reported good tolerance to the mentioned drugs. Immediate readings of prick and intradermal tests, performed with the suspected drugs, were negative. Late readings (48 and 72 hours) of epicutaneous tests were also negative. At 72 hours, prick and intradermal tests to phenylephrine were positive. Allergic blepharoconjunctivitis to phenylephrine was diagnosed. Phenylephrine is an extensively used midriatic that can act as a potent sensitizing agent and can be the cause of allergic contact reactions in exposed patients. With this case we illustrate the relevance of late readings of intradermal tests in the diagnosis of late hypersensitivity drug reactions. The authors discuss about possible mechanisms responsible for negative results of epicutaneous tests

Las reacciones alérgicas por colirios midriáticos son raras, a pesar de lo ampliamente usados por los oftalmólogos. La fenilefrina es responsable del 54-95% de los casos publicados. Presentamos el caso de un varón de 56 años, con blefaroconjuntivitis tras la instilación de un colirio compuesto de fenilefrina 5%, tropicamida 0,5% y oxibruprocaina. El paciente había tolerado anteriormente estos medicamentos. La lectura inmediata de las pruebas cutáneas (prick e intradermo) efectuadas con esos medicamentos, fue negativa. La lectura tardía (48 y 72 horas) de los tests epicutáneos también fue negativa. A las 72 horas, la prueba con fenilefrina, tanto el prick como la intradérmica, fue positiva. Por ello, el diagnóstico fue blefaroconjuntivitis alérgica por fenilefrina. La fenilefrina es una midriático ampliamente usado que puede actuar como agente sensibilizante, causando reacciones alérgicas de contacto en los pacientes expuestos. Este caso ilustra sobre la relevancia de la lectura tardía de las pruebas cutáneas para el diagnóstico de las reacciones tardías de hipersensibilidad. Se discuten los posibles mecanismos responsables de los resultados negativos de las pruebas epicutáneas

Delayed hypersensitivity reactions to corticosteroids

Background: Corticosteroids (CS) are widely used in the treatment of asthma, allergic disorders and other immunological diseases due to their anti-inflammatory and immunosuppressive properties. Physicians seldom suspect them of causing allergic reactions. However, more and more cases of hypersensitivity reactions to CS have been described. Reports of delayed allergic reactions to CS in patients with asthma or allergic rhinitis are scarce. Material and methods: We report the case of a 44-year-old woman with a history of mild persistent asthma and intermittent allergic rhinitis, treated with inhaled beclomethasone and salbutamol, who developed a delayed mucocutaneous and respiratory reaction after substitution of beclomethasone with budesonide. Conclusions: The interest of this case lies in the rarity of allergic reactions from inhaled CS in patients with asthma and/or rhinitis. These reactions therefore represent a diagnostic and therapeutic challenge

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Nimesulide-induced fixed drug eruption

Background: Nimesulide is a cyclooxygenase (COX) inhibitor with a high degree of selectivity to COX-2. It is a widely used and well tolerated nonsteroidal antiinflammatory drug that also has analgesic and antipyretic properties. The most frequently reported side effects concern the gastrointestinal tract. Pruritus and skin rash are the most common cutaneous adverse reactions. There are only eight cases of fixed drug eruptions due to nimesulide, described in the literature. Case report: The authors report a case of a patient with a history of antihistamine hypersensitivity who developed a bullous form of pigmented fixed drug eruption after nimesulide ingestion. Patch tests performed on residual skin lesion were positive to nimesulide, confirming that this was the culprit drug. Conclusions: Fixed drug eruptions are common cutaneous drug reactions, often misdiagnosed. A detailed anamnesis and physical examination are the key to suspect this condition

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