Background: Warfarin is an anticoagulant that is used for the prophylactic and therapeutic treatment for a wide range of thrombo-embolic disorders. The prescribing and monitoring of warfarin therapy is challenging due to the fact that warfarin exhibits numerous interactions with other drugs and a variety of factors that influence the dosing of warfarin. Objective: The general objective of this study was to investigate the prevalence of drugs prescribed with warfarin that may have a potential drug-drug interaction (DDI) with warfarin. Methods: This was a cross-sectional, observational or qualitative study that was conducted on medicine claims data of a pharmaceutical benefit management company for patients receiving warfarin therapy for a six year period, ranging from 1 January 2005 to 31 December 2010. Drug products that were co-prescribed with warfarin were also identified from the medicine claims database. The total number of prescriptions for all drug products during the study period were analysed and compared to the warfarin dataset. This was done by means of the SAS 9.1® computer package (SAS Institute, 2004). The total number of prescriptions and medicine items claimed from the database during the study period were respectively 49 523 818 and 118 305 941. Potential DDls between warfarin and coprescribed drugs were identified and classified according to a clinically significant rating. The clinically significance ratings of potential DDls are described in three degrees of severity, identified as major, moderate and minor (Tatro, 2011 :xiv). Results: The database consisted of 427 238 warfarin prescriptions and 427 744 warfarin medicine items, which represented 0.9% of the total number of prescriptions and 0.4% of total number of medicine items. The total number of patients who claimed warfarin prescriptions through the database represented 0.9% (n=68 575) of the total number of patients who claimed prescriptions in the total database (2005-2010). General practitioners prescribed the highest frequency of warfarin medicine items, representing 58.3% (n=249 202) of the total number prescribed. The age group that claimed the highest frequency of warfarin prescriptions (n=327 592, 76.6%) and the highest frequency of warfarin medicine items (n=327 984, 76.7%) was age group 4 (consisting of patients 59 years and older). The distribution between females and males regarding warfarin prescriptions claimed (n=205 999, 48.2%; n=221 117, 51.8%) and warfarin medicine items claimed (n=206 232, 48.2%; n=221 390, 51.8%) were almost equal. General practitioners prescribed the highest average PDD (7.01 mg ± 9.86 mg) of warfarin medicine items. Paediatric cardiologists prescribed the lowest average PDD (4.61 mg ± 1.29 mg) of warfarin medicine items. A d-value of 0.1 indicates that there is no practical difference of the average PDD between general practitioners and paediatric cardiologists. The average PDD of warfarin medicine items between females (6.60 mg ± 9.06 mg) and males (6.74 mg± 8.41 mg) was almost equal. The age group who was prescribed the highest average PDD was age group 2 (consisting of patients 20 years to 39 years old) (7.42 mg± 7.42 mg). Age group 4 (consisting of patients 59 years and older) (6.50 mg± 8.90 mg) was prescribed the lowest average PDD of warfarin medicine items. A d-value of 0.1 indicates that there is no practical difference of the average PDDs of warfarin medicine items between these two age groups. The results revealed that drugs with a significance rating (SR) of 1 (n=155 066, 43.3%), 2 (n=30128, 8.4%), 4 (n=137144, 38.3%), and 5 (n=36144, 10.1%) were co-prescribed with warfarin in the six year study period. The five drugs that was co-prescribed with warfarin most frequently was aspirin (n=48 903, 13.6%), thyroxine (n=33 954, 9.5%), amiodarone (n=25 056, 7.0%), simvastatin (n=19 070, 5.3%) and celecoxib (n=10 794, 3.0%). These five drugs have a SR of 1. Conclusions: This study showed that the top five drugs most frequently prescribed with warfarin are aspirin, thyroxine, amiodarone, simvastatin and celecoxib. These drugs can potentially interact with warfarin. The potential interactions of these drugs are rated with a significance rating of 1. This concludes that drugs that can potentially cause life threatening effects and permanent damage are commonly co-prescribed with warfarin. Clinical data concerning the INR or PT must be obtained in order to evaluate whether or not warfarin therapy is changed when a potentially interacting drug is co-prescribed. The age of the patients as well as the duration of warfarin treatment should also be obtained in order to assess whether warfarin treatment is changed with the progression of age. / MPharm (Pharmacy Practice), North-West University, Potchefstroom Campus, 2013

Background: Warfarin is an anticoagulant that is used for the prophylactic and therapeutic treatment for a wide range of thrombo-embolic disorders. The prescribing and monitoring of warfarin therapy is challenging due to the fact that warfarin exhibits numerous interactions with other drugs and a variety of factors that influence the dosing of warfarin. Objective: The general objective of this study was to investigate the prevalence of drugs prescribed with warfarin that may have a potential drug-drug interaction (DDI) with warfarin. Methods: This was a cross-sectional, observational or qualitative study that was conducted on medicine claims data of a pharmaceutical benefit management company for patients receiving warfarin therapy for a six year period, ranging from 1 January 2005 to 31 December 2010. Drug products that were co-prescribed with warfarin were also identified from the medicine claims database. The total number of prescriptions for all drug products during the study period were analysed and compared to the warfarin dataset. This was done by means of the SAS 9.1® computer package (SAS Institute, 2004). The total number of prescriptions and medicine items claimed from the database during the study period were respectively 49 523 818 and 118 305 941. Potential DDls between warfarin and coprescribed drugs were identified and classified according to a clinically significant rating. The clinically significance ratings of potential DDls are described in three degrees of severity, identified as major, moderate and minor (Tatro, 2011 :xiv). Results: The database consisted of 427 238 warfarin prescriptions and 427 744 warfarin medicine items, which represented 0.9% of the total number of prescriptions and 0.4% of total number of medicine items. The total number of patients who claimed warfarin prescriptions through the database represented 0.9% (n=68 575) of the total number of patients who claimed prescriptions in the total database (2005-2010). General practitioners prescribed the highest frequency of warfarin medicine items, representing 58.3% (n=249 202) of the total number prescribed. The age group that claimed the highest frequency of warfarin prescriptions (n=327 592, 76.6%) and the highest frequency of warfarin medicine items (n=327 984, 76.7%) was age group 4 (consisting of patients 59 years and older). The distribution between females and males regarding warfarin prescriptions claimed (n=205 999, 48.2%; n=221 117, 51.8%) and warfarin medicine items claimed (n=206 232, 48.2%; n=221 390, 51.8%) were almost equal. General practitioners prescribed the highest average PDD (7.01 mg ± 9.86 mg) of warfarin medicine items. Paediatric cardiologists prescribed the lowest average PDD (4.61 mg ± 1.29 mg) of warfarin medicine items. A d-value of 0.1 indicates that there is no practical difference of the average PDD between general practitioners and paediatric cardiologists. The average PDD of warfarin medicine items between females (6.60 mg ± 9.06 mg) and males (6.74 mg± 8.41 mg) was almost equal. The age group who was prescribed the highest average PDD was age group 2 (consisting of patients 20 years to 39 years old) (7.42 mg± 7.42 mg). Age group 4 (consisting of patients 59 years and older) (6.50 mg± 8.90 mg) was prescribed the lowest average PDD of warfarin medicine items. A d-value of 0.1 indicates that there is no practical difference of the average PDDs of warfarin medicine items between these two age groups. The results revealed that drugs with a significance rating (SR) of 1 (n=155 066, 43.3%), 2 (n=30128, 8.4%), 4 (n=137144, 38.3%), and 5 (n=36144, 10.1%) were co-prescribed with warfarin in the six year study period. The five drugs that was co-prescribed with warfarin most frequently was aspirin (n=48 903, 13.6%), thyroxine (n=33 954, 9.5%), amiodarone (n=25 056, 7.0%), simvastatin (n=19 070, 5.3%) and celecoxib (n=10 794, 3.0%). These five drugs have a SR of 1. Conclusions: This study showed that the top five drugs most frequently prescribed with warfarin are aspirin, thyroxine, amiodarone, simvastatin and celecoxib. These drugs can potentially interact with warfarin. The potential interactions of these drugs are rated with a significance rating of 1. This concludes that drugs that can potentially cause life threatening effects and permanent damage are commonly co-prescribed with warfarin. Clinical data concerning the INR or PT must be obtained in order to evaluate whether or not warfarin therapy is changed when a potentially interacting drug is co-prescribed. The age of the patients as well as the duration of warfarin treatment should also be obtained in order to assess whether warfarin treatment is changed with the progression of age. / MPharm (Pharmacy Practice), North-West University, Potchefstroom Campus, 2013

“Off-label use” is defined as the use of medicine for indications other than recommended or registered for, e.g. the prescribing of a particular active substance for a patient younger than the substance is recommended or indicated for, or different formulations or dosages of a substance (Ekins-Daukes et al., 2004:349; Stedman’s medical dictionary, 2006). Off-label prescribing is common, and fluctuates by physician, patient and drug (Eguale et al., 2012:781). Drug classes most commonly prescribed off-label include anti-asthmatic, cardiovascular drugs and antidepressants. Lee et al. (2012:140) found that 9 out of 10 antidepressants prescribed were associated with unapproved usage of antidepressants. An antidepressant can be defined as a substance that prevents or relieves depression or depressive episodes (Mosby, 2009:115). There is paucity of information on the off-label prescribing practices of antidepressants in the South African private health sector. According to Eguale et al. (2012:781), the paucity of information on off-label prescribing practices may be, in part, ascribed to the difficulty in the establishment of reasons for treatment. The objective of this study was to determine the prescribing patterns of antidepressants as well as to identify off-label prescribing of antidepressants among adults in a section of the private health sector of South Africa by using a medicine claims database. A quantitative and observational, descriptive cross-sectional design was followed in this study. Data for a period of a year, from January to December 2010 were obtained for analysis. The data set consisted of medicine claims for a total number of 1 220 289 patients, containing a total of 8 515 428 prescriptions and 20 527 777 medicine items. The study population (patients receiving antidepressants 18 years and older) accounted for 14.8% (n = 1 220 289) of the total data set. The average age of patients receiving antidepressants was 56.1 ± 16.6 (median = 56.2) (Inter quartile range = 43.3–68.1). Results of the study showed that antidepressant prescriptions accounted for 8.3% (n = 8 515 428) of all prescriptions claimed during 2010. A total 3.5 % (n = 20 527 777) of antidepressants were claimed during the study period. Using the DU90% method it was established that the majority of antidepressant medicine items were prescribed by general practitioners (i.e. 75.7%, n = 702 285) and psychiatrists (14.9%, n = 702 285). Almost 72% (n = 702 885) of antidepressant medicine items claimed for the study population were for women. The most prescribed antidepressants (based on the DU90%) were amitriptyline (20.6%, n = 702 885), citalopram (19.2%), escitalopram (14.6%), fluoxetine (11.7%), venlafaxine (5.7%), paroxetine (5.2%), duloxetine (4.4%), sertraline (3.8%), bupropion (3.1%) and mirtazapine (2.6%). Amitriptyline accounted for 82.4% of off-label prescriptions (n = 2 635), whereas escitalopram and fluoxetine accounted for 4.2% and 3.8%, respectively. The tricyclic antidepressants (TCAs) were mostly prescribed off-label for migraine, headache and sleep disorders. The off-label prescribing of selective serotonin re-uptake inhibitors (SSRIs) included menopause, schizophrenia and headache. The off-label indicated prescriptions of the serotonin and noradrenaline re-uptake inhibitors (SNRIs) were mostly for schizophrenia and other anxiety disorders. Mirtazapine, a serotonin modulator/tetracyclic antidepressant, was mostly prescribed off-label for anxiety disorders. Off-label prescriptions for bupropion, a noradrenaline and dopamine re-uptake inhibitor mainly included other anxiety disorders and attention deficit hyperactivity disorder (ADHD). Furthermore, the prescribed daily dose (PDD) of each active antidepressant for all off-label indications was determined. In conclusion: This study investigated the off-label prescribing patterns of antidepressants among adults a section of the private health sector of a South Africa, using a large medicine claims database. Recommendations for future research were made. / MPham (Pharmacy Practice), North-West University, Potchefstroom Campus, 2014

“Off-label use” is defined as the use of medicine for indications other than recommended or registered for, e.g. the prescribing of a particular active substance for a patient younger than the substance is recommended or indicated for, or different formulations or dosages of a substance (Ekins-Daukes et al., 2004:349; Stedman’s medical dictionary, 2006). Off-label prescribing is common, and fluctuates by physician, patient and drug (Eguale et al., 2012:781). Drug classes most commonly prescribed off-label include anti-asthmatic, cardiovascular drugs and antidepressants. Lee et al. (2012:140) found that 9 out of 10 antidepressants prescribed were associated with unapproved usage of antidepressants. An antidepressant can be defined as a substance that prevents or relieves depression or depressive episodes (Mosby, 2009:115). There is paucity of information on the off-label prescribing practices of antidepressants in the South African private health sector. According to Eguale et al. (2012:781), the paucity of information on off-label prescribing practices may be, in part, ascribed to the difficulty in the establishment of reasons for treatment. The objective of this study was to determine the prescribing patterns of antidepressants as well as to identify off-label prescribing of antidepressants among adults in a section of the private health sector of South Africa by using a medicine claims database. A quantitative and observational, descriptive cross-sectional design was followed in this study. Data for a period of a year, from January to December 2010 were obtained for analysis. The data set consisted of medicine claims for a total number of 1 220 289 patients, containing a total of 8 515 428 prescriptions and 20 527 777 medicine items. The study population (patients receiving antidepressants 18 years and older) accounted for 14.8% (n = 1 220 289) of the total data set. The average age of patients receiving antidepressants was 56.1 ± 16.6 (median = 56.2) (Inter quartile range = 43.3–68.1). Results of the study showed that antidepressant prescriptions accounted for 8.3% (n = 8 515 428) of all prescriptions claimed during 2010. A total 3.5 % (n = 20 527 777) of antidepressants were claimed during the study period. Using the DU90% method it was established that the majority of antidepressant medicine items were prescribed by general practitioners (i.e. 75.7%, n = 702 285) and psychiatrists (14.9%, n = 702 285). Almost 72% (n = 702 885) of antidepressant medicine items claimed for the study population were for women. The most prescribed antidepressants (based on the DU90%) were amitriptyline (20.6%, n = 702 885), citalopram (19.2%), escitalopram (14.6%), fluoxetine (11.7%), venlafaxine (5.7%), paroxetine (5.2%), duloxetine (4.4%), sertraline (3.8%), bupropion (3.1%) and mirtazapine (2.6%). Amitriptyline accounted for 82.4% of off-label prescriptions (n = 2 635), whereas escitalopram and fluoxetine accounted for 4.2% and 3.8%, respectively. The tricyclic antidepressants (TCAs) were mostly prescribed off-label for migraine, headache and sleep disorders. The off-label prescribing of selective serotonin re-uptake inhibitors (SSRIs) included menopause, schizophrenia and headache. The off-label indicated prescriptions of the serotonin and noradrenaline re-uptake inhibitors (SNRIs) were mostly for schizophrenia and other anxiety disorders. Mirtazapine, a serotonin modulator/tetracyclic antidepressant, was mostly prescribed off-label for anxiety disorders. Off-label prescriptions for bupropion, a noradrenaline and dopamine re-uptake inhibitor mainly included other anxiety disorders and attention deficit hyperactivity disorder (ADHD). Furthermore, the prescribed daily dose (PDD) of each active antidepressant for all off-label indications was determined. In conclusion: This study investigated the off-label prescribing patterns of antidepressants among adults a section of the private health sector of a South Africa, using a large medicine claims database. Recommendations for future research were made. / MPham (Pharmacy Practice), North-West University, Potchefstroom Campus, 2014

Thesis (M.Pharm. (Pharmacy Practice))--North-West University, Potchefstroom Campus, 2008.

Acid-related disorders are common, chronic conditions that have considerable impact on a patient's quality of life. In a study conducted by Majumdar et al. (2003:2411) the prevalence of chronic acid-related disorders was 2.3%. Acid-related disorders represent a major financial consideration with respect to the costs of drug prescribing (Whitaker, 1998:6). Health care cost increases each year. This leads to an increased interest in economic evaluation of health care and medical technologies (Anell & Svarvar, 2000:175). Health care providers no longer make treatment decisions independent of the consideration of the resultant cost. The treatment provided must not only provide value but the value must be documented to justify spending money. Economic evaluation research has emerged to offer guidance to policy makers, practitioners, health plans and institutions facing difficult treatment and coverage decisions (Ellis era/., 2002:271). The main objectives of this study were to investigate the prescribing patterns and cost of acid reducing medicine with special reference to proton pump inhibitors and histamine-2 receptor antagonists in a section of the private health care sector of South Africa from 2001 to 2006. A longitudinal retrospective drug utilisation study was done on acid reducing medicine items claimed through a national medicine claims database. The five study years were 2001, 2002, 2004, 2005 and 2006. All the study years stretched from 1 January to 31 December. It was determined that acid reducing medicine items prescribed decreased from 2.74% during 2001 to 2.50% during 2006 of all medicine items claimed. The same decreasing trend was observed regarding the cost of acid reducing medicine items. The cost percentage decreased from 4.89% (2001) to 3.72% (2006). However, the average cost per medicine item for the acid reducers increased by 5.35% from 2001 (R230.04 ± 176.29) to 2002 (R243.72 ± 184.18) and then decreased by 15.23% from 2002 to 2004. It again decreased with 15.05% from 2004 (R206.19 ± 179.42) to 2006 (R175.70 ± 172.55). The changes in the average cost of acid reducers were of no practical significance. Proton pump inhibitors represented about half of the acid reducing medicine items prescribed and more than 70% of the total cost of acid reducing medicine items during the study years. The average cost of PPIs revealed a practical significant decrease (d > 0.8) from 2002 (R372.42 ± 156.62) to 2006 (R241.56 ± 177.21). H2RAs contributed between 15.00% and 18.26% of all acid reducing medicine items while contributing to between 9.68% and 16.85% of the total cost of all acid reducers. The active ingredient most often prescribed was lansoprazole during 2001 and 2002, esomeprazole during 2004 and omeprazole during 2005 and 2006. Lanzor® 30mg was the acid reducer with the highest cost from 2001 to 2005, while Pariet® 20mg took the lead in 2006. Zantac® 150mg effervescent tablets were the H2RA, with the highest cost, during the five study years. The percentage innovator items decreased by 4.50% from 2001 to 2002, increased by 1.01% from 2002 to 2004 and decreased again by 31.06% from 2004 to 2006. The slight increase in the percentage innovator medicine items claimed from 2002 to 2004 may be explained by the introduction of Nexiam® (esomeprazole) into the market in 2002. The total number of generic medicine items claimed contributed between 9.62% (n = R1 788 242.25) in 2001 and 30.75% (n = R3 196 163.34) in 2006 of the total cost of acid reducing medicine items. The average cost per day of innovator medicine items was higher than the average cost per day of generic medicine items. This might be explained by a lower average cost for generic medicine items. It was also determined that the prevalence of the two-drug regimens was the highest during the five study years. The Helicobacter pylori (H.pylori) eradication treatments, which included different antibiotics, increased from 2.72% in 2001 to 5.05% in 2006. The PDD for most of the active ingredients of H2RAs and PPIs remained stable during the study years. However, it appears that the PDDs, of the PPIs, active ingredients were more constant than the PDDs, or the H2RAs, active ingredients. The median of the different PPI active ingredients was reasonably more constant than the median of the different H2RA active ingredients. Thus the changes between the PPIs' and H2RAs' active ingredients might be explained by the variation in the median (the number of days the relevant medicine item was claimed for). It is then also recommended that the aspects of generic substitution as well as the usage of H2RAs as prescribed vs. self medication should be further investigated to increase possible cost savings. / Thesis (M.Pharm. (Pharmacy Practice))--North-West University, Potchefstroom Campus, 2008.

Acid-related disorders are common, chronic conditions that have considerable impact on a patient's quality of life. In a study conducted by Majumdar et al. (2003:2411) the prevalence of chronic acid-related disorders was 2.3%. Acid-related disorders represent a major financial consideration with respect to the costs of drug prescribing (Whitaker, 1998:6). Health care cost increases each year. This leads to an increased interest in economic evaluation of health care and medical technologies (Anell & Svarvar, 2000:175). Health care providers no longer make treatment decisions independent of the consideration of the resultant cost. The treatment provided must not only provide value but the value must be documented to justify spending money. Economic evaluation research has emerged to offer guidance to policy makers, practitioners, health plans and institutions facing difficult treatment and coverage decisions (Ellis era/., 2002:271). The main objectives of this study were to investigate the prescribing patterns and cost of acid reducing medicine with special reference to proton pump inhibitors and histamine-2 receptor antagonists in a section of the private health care sector of South Africa from 2001 to 2006. A longitudinal retrospective drug utilisation study was done on acid reducing medicine items claimed through a national medicine claims database. The five study years were 2001, 2002, 2004, 2005 and 2006. All the study years stretched from 1 January to 31 December. It was determined that acid reducing medicine items prescribed decreased from 2.74% during 2001 to 2.50% during 2006 of all medicine items claimed. The same decreasing trend was observed regarding the cost of acid reducing medicine items. The cost percentage decreased from 4.89% (2001) to 3.72% (2006). However, the average cost per medicine item for the acid reducers increased by 5.35% from 2001 (R230.04 ± 176.29) to 2002 (R243.72 ± 184.18) and then decreased by 15.23% from 2002 to 2004. It again decreased with 15.05% from 2004 (R206.19 ± 179.42) to 2006 (R175.70 ± 172.55). The changes in the average cost of acid reducers were of no practical significance. Proton pump inhibitors represented about half of the acid reducing medicine items prescribed and more than 70% of the total cost of acid reducing medicine items during the study years. The average cost of PPIs revealed a practical significant decrease (d > 0.8) from 2002 (R372.42 ± 156.62) to 2006 (R241.56 ± 177.21). H2RAs contributed between 15.00% and 18.26% of all acid reducing medicine items while contributing to between 9.68% and 16.85% of the total cost of all acid reducers. The active ingredient most often prescribed was lansoprazole during 2001 and 2002, esomeprazole during 2004 and omeprazole during 2005 and 2006. Lanzor® 30mg was the acid reducer with the highest cost from 2001 to 2005, while Pariet® 20mg took the lead in 2006. Zantac® 150mg effervescent tablets were the H2RA, with the highest cost, during the five study years. The percentage innovator items decreased by 4.50% from 2001 to 2002, increased by 1.01% from 2002 to 2004 and decreased again by 31.06% from 2004 to 2006. The slight increase in the percentage innovator medicine items claimed from 2002 to 2004 may be explained by the introduction of Nexiam® (esomeprazole) into the market in 2002. The total number of generic medicine items claimed contributed between 9.62% (n = R1 788 242.25) in 2001 and 30.75% (n = R3 196 163.34) in 2006 of the total cost of acid reducing medicine items. The average cost per day of innovator medicine items was higher than the average cost per day of generic medicine items. This might be explained by a lower average cost for generic medicine items. It was also determined that the prevalence of the two-drug regimens was the highest during the five study years. The Helicobacter pylori (H.pylori) eradication treatments, which included different antibiotics, increased from 2.72% in 2001 to 5.05% in 2006. The PDD for most of the active ingredients of H2RAs and PPIs remained stable during the study years. However, it appears that the PDDs, of the PPIs, active ingredients were more constant than the PDDs, or the H2RAs, active ingredients. The median of the different PPI active ingredients was reasonably more constant than the median of the different H2RA active ingredients. Thus the changes between the PPIs' and H2RAs' active ingredients might be explained by the variation in the median (the number of days the relevant medicine item was claimed for). It is then also recommended that the aspects of generic substitution as well as the usage of H2RAs as prescribed vs. self medication should be further investigated to increase possible cost savings. / Thesis (M.Pharm. (Pharmacy Practice))--North-West University, Potchefstroom Campus, 2008.