A retrospective analysis of the prescribing patterns of isotretinoin
Kruger, Ulrich Victor
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Acne is a very common disease affecting approximately 85% of people in some stage of their life (Wolff et al., 2005:2). The systemic drug isotretinoin is the only acne drug which has an influence on all the pathophysiological factors of this highly prevalent disease and is considered as the most effective treatment for acne, although it should be limited to the treatment of severe acne. Isotretinoin prescribing is under the largest risk-minimisation programme (called iPLEDGE) ever implemented for a drug in the United States of America, due to concerns with pregnancies during isotretinoin treatment (Honein et al., 2007:11). In comparison South Africa has no equal managing programme to regulate isotretinoin prescribing and the need to identify certain prescribing patterns is deemed necessary. The general objective of this study was to analyse the prescribing patterns of isotretinoin, including aspects of cost, in a section of the private healthcare sector of South Africa. A quantitative, retrospective drug utilisation review was performed to evaluate the prescribing patterns and cost of isotretinoin containing products claimed through a pharmacy benefit management organisation, over the study period of 2005 and 2006. Data were analysed by using the Statistical Analysis System, 9.1 (SAS). The information of prescriber, age, gender, and cost of isotretinoin usage were considered and evaluated. A total number of 6 427 and 6 927 patients claimed 18 589 and 20 232 isotretinoin prescriptions respectively during 2005 and 2006. Isotretinoin total costs contributed to 34.4% (n = R6 810 090) and 36.3% (n = R6 533 241) of the total identified acne medicine costs for 2005 and 2006 respectively. Isotretinoin represented the highest percentage of total costs in relation to any other acne product identified in both study years. Average costs of R314.82 ± 205.92 per prescribed isotretinoin item in 2005 and R277.63 ± 192.63 in 2006 were recorded in comparison to the total database medicine item cost of R95.33 ± 192.21 in 2005 and R95.33± 227.99 in 2006. The generic products of isotretinoin were claimed at a lower ratio (generic vs. innovator product ratio of 1.8:1 in 2005 and 2.2:1 in 2006) in relation to the total database (generic ratio of 3:1 in both years). Dermatologists prescribed 68.2% and 65.7% of isotretinoin prescriptions and general practitioners 27.5% and 29.7%. General practitioners were more likely to prescribe the generic equivalents of isotretinoin (68.9% in 2005 and 72.1% in 2006) in comparison to dermatologists (59.7% in 2005 and 63.4% in 2006). The teenage group 12 to 19 years received 48.4% (n = 8 989) and 47.7% (n = 9 656) of isotretinoin prescriptions claimed respectively at an estimated cost of R275 000 and R260 000 per 10 000 beneficiaries in this age group respectively for 2005 and 2006. There were 71 patients identified over both study years in the age group younger than 12 years, in which isotretinoin use is not recommended. Female patients received 56.2% (n = 10 450) and 57.4% (n = 11 610) of the total number of isotretinoin prescriptions claimed respectively for 2005 and 2006. The average cost per isotretinoin prescription claimed for male patients was higher (R406.36 ± 233.76 and R358.69 ± 218.29 respectively for 2005 and 2006) in relation to female patients (R335.15 ± 209.98 and R296.36 ± 197.74 respectively for 2005 and 2006). The median ages for female and male patients were 21 years and 18 years respectively. The concern, however, was the high number of female patients of child-bearing potential identified (2 892 and 3 201 female patients respectively for 2005 and 2006), claiming their isotretinoin prescriptions. Systemic isotretinoin occurred alone in 70.8% and 69.3% of prescriptions claimed respectively for 2005 and 2006. Oral contraceptives occurred in combination with isotretinoin in only 8.6% and 9.2% of isotretinoin prescriptions claimed. The contra-indicated use of a systemic tetracycline in combination with systemic isotretinoin occurred in 139 (0.75%) and 130 (0.64%) prescriptions. It can be concluded that the use of isotretinoin increased. Dermatologists played the major role in prescribing isotretinoin. The number of female isotretinoin users (especially of child-bearing potential) could be a concern, although pregnancy prevalence should be identified in South Africa. It is recommended that further studies be conducted in South Africa regarding the usage and control of isotretinoin, including the extension of regulating programmes, with special reference to age and gender. Effective management of the increasing popularity of this ultimately successful acne treatment is of utmost importance to ensure the effective and safe usage of isotretinoin.
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