Introduction
Peanut allergy is being increasingly recognised and prevalence is reported to be in the range of 1–3 per cent for the population. There are no sequential data which accurately report the prevalence of peanut allergy in the UK population, but in common with other allergic conditions, the available evidence indicates that the prevalence is increasing.1
Although the risk of peanut allergy after ingestion of peanut containing foods is well recognised, the role of peanut oil as an allergen is controversial. Peanut oil, otherwise known as arachis oil, is the refined fatty oil obtained from the seeds of Arachis hypogaea L (peanut). This part of the nut has not been associated with allergic reactions in individuals with peanut allergy.
The Chief Medical Officer's update in August 20032 advised that there was insufficient evidence to conclude that exposure to medicinal products containing peanut oil leads to sensitisation to peanut protein. However, although the risk of an allergic reaction is low, as a precaution the Committee on Safety of Medicines (CSM) has advised that:
1 Patients known to be allergic to peanuts should not use medicines containing peanut oil.
2 As there is a possible relationship between peanut allergy and soya allergy, patients allergic to soya should also avoid medicinal products containing peanut oil.
For a practising otolaryngologist this is highly relevant as one of the most widely prescribed products, Naseptin® (Alliance), contains peanut oil. We therefore carried out a survey to find out how well this advice was followed. The following case report shows the increasing public awareness of peanut allergy.
Case report
A nine-year-old boy was seen in clinic with a history of recurrent epistaxis and examination revealed prominent vessels on the anterior nasal septum. These were treated with silver nitrate and the boy was prescribed Naseptin cream to be applied to the affected area for two weeks. The next morning the consultant was contacted by the boy's mother who informed him that her son had been excluded from school because his teacher had a severe nut allergy. Despite the best efforts of the consultant to reassure the headmaster that the likelihood of the teacher coming into contact with the cream was very remote indeed and probably less than coming into contact with nut products if walking around a supermarket, the headmaster refused to allow the boy back into the class. As a compromise it was agreed that the boy could still attend school but would need to join another class for the duration of his treatment with Naseptin cream.
Materials and methods
A simple questionnaire was designed using just three questions:
1 Do you use Naseptin® cream in your clinical practice?
2 Are you aware that Naseptin® cream contains peanut oil?
3 If you prescribe Naseptin® cream, do you ask your patients whether they have peanut allergy?
This questionnaire was sent out to all ENT practitioners registered with the British Association of Otolaryngologists. The questionnaire was sent out in June 2006 and data were collected until September 2006. A total of 901 questionnaires were sent out of which 434 were returned. Twelve questionnaires were disregarded as answers were incomplete. A total of 422 questionnaires were analysed, and although this is only 46 per cent of the sample group, we feel that it is a sufficiently large number to be representative of the ENT practice in the UK.
Results and analysis
Results confirmed that a majority of ENT practitioners, who responded to the survey, use Naseptin cream in their practice (90.4 per cent of consultants, 100 per cent of registrars). Amongst users, most are aware that Naseptin contains peanut oil (overall 81.5 per cent with 74.3 per cent of practicing consultants and 93.6 per cent of registrars). However, not all those who prescribe Naseptin ask their patients whether they have a peanut allergy (62.6 per cent consultants, 87.3 per cent of registrars) (Figures 1 and 2).
Awareness of the arachis oil content of Naseptin amongst prescribing otolaryngologists (per cent). Light grey = per cent aware; dark grey = per cent unaware
Prescribing otolaryngologists (per cent) who ask patients about peanut allergy. Light grey = per cent who asked patients; dark grey = per cent who did not ask patients
From the results it is clear that most practitioners who use Naseptin are aware of the fact that it contains peanut oil, however, not all follow the advice of the Committee on Safety of Medicines and ask patients whether they have a peanut allergy.
Discussion
The issue of allergenicity of refined peanut oil (arachis oil) is controversial and the literature does not give a clear answer. Taylor et al. Reference Taylor, Busse, Sachs, Parker and Yunginger3 studied 10 peanut sensitive volunteers who received either peanut oil or olive oil in the control arm. No allergic reactions to the peanut oil were observed. This was confirmed in a second double-blind controlled studyReference Hourihane, Bedwani, Dean and Warner4 where 60 peanut sensitive volunteers received either crude peanut oil or refined peanut oil and 10 per cent of volunteers experienced an allergic reaction to the crude peanut oil but no allergic reactions were observed with the refined peanut oil. However, it has been suggested that exposure to arachis oil in infancy can lead to an increased risk of developing peanut allergy. Lack et al. Reference Lack, Fox, Northstone and Golding5 looked at a cohort of 49 children with a history of peanut allergy. Through interviews with the parents, the authors showed a significant relationship between peanut allergy and the use of skin preparations containing peanut oils. They therefore concluded that sensitisation to peanut protein may occur in children through the application of peanut oil to inflamed skin. However, since it was a retrospective cohort study the relationship found might be coincidental and further studies are required to confirm these findings. Despite this, various authors are of the opinion that the increasing incidence in peanut allergy could be explained by sensitisation through topical skin preparations containing peanut oil.Reference Weeks6, Reference Merz7
• Naseptin cream is widely used amongst ENT practitioners
• There have been concerns as to whether the use of Naseptin cream is appropriate in patients with peanut allergy
• The issue of allergenicity of refined peanut oil (arachis oil) is controversial and the literature does not give a clear answer
• The Committee on Safety of Medicines considers that there is insufficient evidence to suggest that exposure to medicinal products containing peanut oil leads to sensitisation to peanut protein; however, they advise to avoid its use in patients who are allergic to peanut
• The manufacturer has currently not received any reports of allergenicity caused by the use of Naseptin cream in peanut allergic patients but they advise in their Summary of Product Characteristics against its use in patients allergic to peanut
• This survey amongst ENT practitioners has shown that although most are aware that Naseptin contains peanut oil not all of those who prescribe Naseptin ask their patients whether they have a peanut allergy
An earlier study by Olszewski et al. Reference Olszewski, Pons, Moutete, Aimone-Gastin, Kanny and Moneret-Vautrin8 demonstrated the persistence of small amounts of allergenic protein (in the range of 0.1–0.2 mcg/g of oil) in peanut oil, despite refinement. However, Peeters et al.,Reference Peeters, Knulst, Rynja, Bruijnzeel-Koomen and Koppelman9 who investigated content of proteins in peanut oils at various stages of refinement by means of enzyme-linked immunosorbent assay, found that refined peanut oils contain less than 0.3 ng/ml of proteins, which is insufficient for allergic sensitisation.
Currently, the manufacturer (Alliance) of Naseptin has not received any reports of allergic-type reactions but does not exclude them due to the possibility of under reporting. (J. Barber, Alliance Pharmaceuticals Ltd, Personal Communication)
Conclusion
Although there is no evidence that refined arachis oil is allergenic in individuals with peanut allergy, there is controversy over whether the exposure to arachis oil can lead to sensitisation to peanut protein. It therefore remains good practice to inform patients about this risk and avoid using arachis oil containing products in peanut allergic patients. Such practice may avoid possible litigation in the future.
