Objective: By examination of the original Yellow Card data to determine the duration of the latent period of the sclerosing peritonitis which formed part of the oculomucocutaneous syndrome that was associated with practolol, the beta-adrenergic receptor blocking agent that was withdrawn from clinical usage in the UK in December 1975 in response to reports of the syndrome.
Method: Relevant drug analysis prints (DAPs) for practolol were obtained from the Medicines and Healthcare Products Regulatory Agency (MHRA) and, by application to the Interim Committee on Yellow Card data, copies were obtained of the anonymised Yellow Card reports for all the 201 cases of sclerosing peritonitis that were reported in patients treated with practolol. These data were used to determine the latent period of this iatrogenic adverse drug reaction.
Results: It was shown that no other cause than practolol operated in all or a majority of the cases of sclerosing peritonitis and the suspected adverse reaction could properly be attributed to the drug. The latent period (the time period between the drug start date and the reaction start date) of the sclerosing peritonitis associated with practolol averaged 201 weeks (range 26-606 weeks; standard deviation 130 weeks).
Conclusion: The latent period of the sclerosing peritonitis that formed part of the practolol oculomucocutaneous syndrome averaged about 4 years and had a range of from 0.5 to over 11.5 years. The Yellow Card Scheme could detect this ultra long-latency adverse reaction.