EXTENDED AND REVISED PORPHYRIA DRUG LIST: SCHEME FOR PREVENTIVE MEASURES IN PORPHYRIA PHARMACOTHERAPY

Thunell S1, Bjernevik K2, Thunell G2

 

1Porphyria Centre Sweden, 2The Swedish Porphyria Association, Stockholm, Sweden

 

 

Background. An inquiry among Swedish carriers of acute porphyria (102 persons, 79 women, 23 men; 20-84 years) yielded 371 reports of intake of 171 different pharmaceutic drugs during the last twelve months. Twenty-four of the drugs were previously unclassified with regard to porphyrinogenicity and 25 classified as dangerous. In no case porphyria symptoms prompting medical attention developed. Conclusion. As previously observed by other workers, most carriers of acute porphyria seem to tolerate most drugs most of the time. The problem in porphyria drug counselling may primarily be to single out the occasional combination of a porphyrinogenic drug and a vulnerable patient that can result in the rise of a porphyria crisis. The "better safe than sorry" principle when adopted in porphyria pharmacotherapy with all probability will result in uncalled for undertreatment. If also potentially porphyrinogenic drugs are considered for use under specific precautions adapted to the actual porphyric vulnerability of the patient, this may be avoided. Extended and revised drug list. By undertaking a porphyrinogenicity classification of all pharmaceuticals included in the Swedish Pharmacopoeia 2003, a larger selection of drugs to consider for use in the acute porphyrias was aimed at. A total of 970 substances were categorized, of which 674 were classified as not or probably not porphyrinogenic, 182 as possibly porphyrinogenic and 113 as probably or most certainly porphyrinogenic. The general criteria used in the classifications will be presented in detail. The list, adopted for patient's use by also including commercial names of the drugs, will be published by the Swedish Porphyria Association, and will also be available in the drug database of the Norwegian and Swedish National Porphyria Centres, where the rational for the categorization of each substance will be given as well. Guide to precautions in drug treatment. In cases of strong or vital indication for drug therapy, by administration of a potentially porphyrinogenic drug unfortunate undertreatment is avoided where no safe alternative is at hand. A prerequisite for this strategy is the undertaking of preventive measures dimensioned to which extent the porphyria gene carrier is open to porphyric bye-effects of the drug. Five vulnerability classes can be deduced from age, gender, previous and current disease activity and current porphyrinogenic burden of the patient. A scheme over precautions to take will be presented in the form of a matrix where recommended measures are presented for each combination of drug porphyrinogenicity and patient vulnerability. The recommendations will also be available through the Norwegian and Swedish National Porphyria Centre's database, calling upon the generic or the commercial name of the substance.