Dose-time relationships for elicitation of contact allergy to para-phenylenediamine.

Skin-sensitizing chemicals exhibit dose-response relationships for the elicitation of contact dermatitis. Previously, considerable work has been carried out in which the elicitation of allergic skin reaction has been examined as a function of the applied concentration. However, the relationship between exposure time, dose and response has not been explored in any depth. The present work has extended our initial assessment of the relationship between both exposure time and concentration for para-phenylenediamine (PPD) in a group of 19 PPD-allergic volunteers. The results clearly demonstrate that a relationship exists between both exposure time and concentration. Positive responses to PPD were directly proportional to exposure time: at 5 min 16% responded; at 15 min, 38%; at 30 min, 50%; and at 120 min, 69%. A similar direct relationship was found between concentration of PPD and response: after 120 min, 22% of patients had responded to 0.01%, and 69% to 1% PPD. All exposures for 1 and 2 min were negative. Subsequent evaluation using repeated 5 min open application testing demonstrated a cumulative effect, as after 8 days 39% of the panel reacted, more than double the number that reacted to a single occluded 5-min treatment. It was noted that there was marked subject variability in exposure time and dose required to elicit an allergic response. These results are of relevance for the general interpretation of patch test data, especially with regard to risk assessment.

An audit of the use of self-administered adrenaline syringes in patients with angio-oedema.

BACKGROUND: Self-administered adrenaline syringes may be prescribed for patients at risk of life-threatening episodes of angio-oedema or anaphylaxis. OBJECTIVES: To determine whether patients are able to use these syringes appropriately and adequately. METHODS: Twenty-nine consecutive patients who had been prescribed self-administered adrenaline syringes for severe angio-oedema were recruited. All completed a questionnaire (unsupervised), and were asked to demonstrate how to use a dummy syringe. RESULTS: Three of 29 (10%) patients had been prescribed syringes in the absence of severe angio-oedema or collapse. Seventeen of 29 (59%) patients had been prescribed two syringes, and 21 of 29 (72%) kept a syringe with them at all times. Twenty of 28 (71%) patients had had the use of a syringe demonstrated to them with the initial prescription, but two of 29 (7%) had never been shown how to use it. Only six of 26 (23%) patients had been told to telephone for an ambulance after using a syringe. Only seven of 29 (24%) patients would use a syringe for an episode of collapse, whereas eight of 28 (29%) would use one for an episode of lip swelling. Nine of 21 (43%) patients had not been warned about adverse effects, although 13 of 20 (65%) given adrenaline had had at least one adverse effect. Of the 25 patients asked to demonstrate their use of a syringe, only 14 (56%) were able to perform all steps correctly, and three (12%) were unable to perform any of the steps. Despite this, all 29 patients felt confident about giving themselves an injection, and most felt more secure having been prescribed syringes. CONCLUSIONS: As self-administered adrenaline syringes are prescribed for life-threatening events, it is vital that they are given to appropriate patients with adequate written instructions and proper demonstration at the time of the initial prescription. As a result of this study we have developed a more detailed patient information leaflet, and all patients are shown how to use a syringe for a second time when attending the clinic for follow-up.