Thank you for publishing a topical article by Professor Barry Kay (Clinical, May 24). I would like to raise a number of issues.
Loratadine is incorrectly spelt and reference is made to 'so-called ''third-generation'' antihistamines', which is currently not included in the classification defined by the British Society for Allergy and Clinical Immunology.
As Professor Kay suggests, these more recently introduced antihistamines 'do not have any advantages over the second-generation selective and non-sedating antihistamines'. I would therefore suggest that these be classed in the same category as selective and non-sedating histamines, criteria that they appear to fulfil.
Such classification systems lend themselves to misrepresentation when based solely on chronology rather than pharmacological and clinical properties.
Although I do not disagree with the table referring to the potential of mizolastine to be cardiotoxic, I believe insufficient information is provided to allay potential concerns.
Through clinical development and post-marketing surveillance, there have been no reports in which cardiotoxicity – in the form of cardiac dysrhythmias – is definitely attributable to the administration of mizolastine.
However, the data sheet clearly indicates the groups of patients who may be at an increased risk of cardiotoxicity, and provides appropriate recommendations for the use of mizolastine.
Dr Jim Laughton
Medical Affairs Manager
Schwarz Pharma UK
Professor Kay replies:
The term 'third-generation antihistamine' is widely used. You only have to type it in to any search engine to appreciate this. It is useful shorthand to describe more recently introduced antihistamines such as desloratadine, levocetirizine and fexofenadine.
I agree the classification is not satisfactory for the reasons given, but the point is every one knows what is meant by third-generation antihistamines even if the terminology is imperfect.
Cardiotoxicity is clearly referred to for mizolastine in the electronic Medicines Compendium and Dr Laughton accepts this. However, he is right that izolastine is only available on prescription. The misspelling of loratadine is a typographical error.