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Mahler C, Jank S, Pruszydlo MG, Hermann K, Gärtner H, Kaltschmidt J, Ludt S, Bertsche T, Haefeli WE, Szecsenyi J. [HeiCare®: a project aiming to improve medication communication across health care sectors]. Dtsch Med Wochenschr 2011; 136:2239-44. [PMID: 22028288 DOI: 10.1055/s-0031-1292036] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
BACKGROUND AND OBJECTIVE Changes between health care sectors represent a critical phase in long-term pharmacotherapy. The aim of the Hei CARE(®) project was to close the communication gap at the interface between primary care physicians (PCP), hospital physicians and patients, and to improve quality and safety of pharmacotherapy. METHODS Physicians who enrolled patients with long-term pharmacotherapy were able to participate in the Hei CARE(®) project. After enrolment the patient's medication was entered in the internet-based medication knowledge data base AiD PRAXIS and checked for medication interactions and optimized if necessary. At hospitalisation medication was transferred electronically to the hospital (AiD KLINIK(®)) and on discharge integrated in the discharge letter and faxed to the primary care physician (PCP). The project was evaluated using quantitative and qualitative methods. Hei CARE(®) -cases, in which medication was transferred electronically as planned, were compared with the other cases. PCPs' experiences were collected in focus groups. RESULTS One thousand and three chronically ill patients of 56 primary care practices participated. 259 patients were hospitalized between October 2005 and March 2009 of which entrance and discharge medication were transferred both ways via the electronic prescribing platform in 67 cases. The number of changes in medication was reduced in comparison to the other cases. Participating PCPs reported positive changes through Hei CARE(®) as well as further potential for optimizing communication across health care sectors. CONCLUSION Use of a common internet-based medication knowledge data base (Hei CARE(®) ) in both health care sectors reduced the number of changes in pharmacotherapy. Seamless care in chronically ill patients was thereby improved. The project also demonstrated that improving communication across health care sectors is a slow process.
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Katzenmaier S, Markert C, Riedel KD, Burhenne J, Haefeli WE, Mikus G. Determining the time course of CYP3A inhibition by potent reversible and irreversible CYP3A inhibitors using A limited sampling strategy. Clin Pharmacol Ther 2011; 90:666-73. [PMID: 21937987 DOI: 10.1038/clpt.2011.164] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We established a new limited sampling strategy to assess CYP3A activity and evaluated the time course of reversible (voriconazole) and irreversible (ritonavir) CYP3A inhibition. In this randomized trial, two groups, each with eight healthy participants, received CYP3A inhibitors voriconazole or ritonavir orally for 9 days, with 3 mg midazolam (MDZ) administered before the inhibitor treatment, on days 1, 2, 3, 5, 8, and 9 during inhibitor treatment, and on days 10, 11, and 12 (3 days) after discontinuation. Plasma MDZ area under the curve (AUC) between 2 and 4 h after oral administration in the form of a solution strongly correlated with MDZ clearance. Using this parameter, maximum inhibition of voriconazole and ritonavir was calculated to have occurred only 48 h after starting of the inhibitor (percentage of baseline MDZ clearance, voriconazole: 10.6%; ritonavir: 8.4%). Recovery of CYP3A activity occurred with a half-life of 24 h after voriconazole, whereas ritonavir inhibition was still strong 3 days after discontinuation. These findings underscore the substantial and gradual alterations in dose requirements in the first days of and after such combination therapies.
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Yimer G, Amogne W, Habtewold A, Makonnen E, Ueda N, Suda A, Worku A, Haefeli WE, Burhenne J, Aderaye G, Lindquist L, Aklillu E. High plasma efavirenz level and CYP2B6*6 are associated with efavirenz-based HAART-induced liver injury in the treatment of naïve HIV patients from Ethiopia: a prospective cohort study. THE PHARMACOGENOMICS JOURNAL 2011; 12:499-506. [DOI: 10.1038/tpj.2011.34] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Ngaimisi E, Mugusi S, Minzi O, Sasi P, Riedel KD, Suda A, Ueda N, Janabi M, Mugusi F, Haefeli WE, Bertilsson L, Burhenne J, Aklillu E. Effect of rifampicin and CYP2B6 genotype on long-term efavirenz autoinduction and plasma exposure in HIV patients with or without tuberculosis. Clin Pharmacol Ther 2011; 90:406-13. [PMID: 21814190 DOI: 10.1038/clpt.2011.129] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
We performed a prospective comparative study to examine, from a pharmacogenetics perspective, the effect of rifampicin (RIF) on long-term efavirenz (EFV) autoinduction and kinetics. In a study population of patients with HIV receiving EFV with RIF (arm 2, n = 54) or without RIF (arm 1, n = 128 controls), intraindividual and interindividual plasma EFV and 8-hydroxyefavirenz levels were compared at weeks 4 and 16 of EFV therapy. In arm 2, RIF was initiated 4 weeks before starting EFV. In controls (arm 1), the plasma EFV was significantly lower whereas 8-hydroxyefavirenz was higher at week 16 as compared to week 4. By contrast, there were no significant differences in plasma EFV and 8-hydroxyefavirenz concentrations over time in arm 2. At week 4, the plasma EFV concentration was significantly lower in arm 2 as compared to arm 1, but no significant differences were observed by week 16. When stratified by CYP2B6 genotype, significant differences were observed only with respect to CYP2B6*1/*1 genotypes. Ours is the first report of the CYP2B6 genotype-dependent effect of RIF on long-term EFV autoinduction.
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Senger C, Seidling HM, Quinzler R, Leser U, Haefeli WE. Design and evaluation of an ontology-based drug application database. Methods Inf Med 2010; 50:273-84. [PMID: 21057721 DOI: 10.3414/me10-01-0013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2010] [Accepted: 06/02/2010] [Indexed: 11/09/2022]
Abstract
OBJECTIVES Several recently published cases of preventable adverse drug reactions were associated with flaws in drug application. However, current clinical decision support (CDS) systems do not properly consider drug application issues and thus do not support effective prevention of such medication errors. With the aim to improve CDS in this respect, we developed a comprehensive model precisely describing all aspects of drug application. METHODS The model consists of 1) a schema comprising all relevant attributes of drug application and 2) an ontology providing a hierarchically structured vocabulary of terms that describe the possible values of the schema's attributes. Finally, medical products were annotated by a semi-automatic term assignment process. For evaluation, we developed an algorithm that uses our model to compute a meaningful similarity between medicinal products with respect to their drug application characteristics. RESULTS Our schema consists of 22 attributes. The ontology contains 248 terms, textual descriptions, and synonym lists. More than 58,700 medicinal products were automatically annotated with >386,600 terms. 2,450 drugs were manually reviewed by experts, adding >4500 terms. The annotation and similarity measure allow for (similarity) searches, clustering, and proper discrimination of drugs with different drug application characteristics. We demonstrated the value of our approach by means of a set of case studies. CONCLUSION Our model enables a detailed description of drug application, allowing for semantically meaningful comparisons of drugs. This is an important prerequisite for improving the ability of CDS systems to prevent prescription errors.
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Ngaimisi E, Mugusi S, Minzi OM, Sasi P, Riedel KD, Suda A, Ueda N, Janabi M, Mugusi F, Haefeli WE, Burhenne J, Aklillu E. Long-term efavirenz autoinduction and its effect on plasma exposure in HIV patients. Clin Pharmacol Ther 2010; 88:676-84. [PMID: 20881953 DOI: 10.1038/clpt.2010.172] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
We investigated the influence of gender and pharmacogenetic variations on long-term efavirenz autoinduction and disposition among patients with HIV in Tanzania (N = 129). Plasma concentrations (at 16 h) of efavirenz and 8-hydroxyefavirenz were quantified at weeks 4 and 16 of therapy. Genotyping was performed to identify cytochrome P450 (CYP) 2B6*6, CYP3A5*3, *6, and *7, and ABCB1-3435 C/T genotypes. There were reductions in the median efavirenz concentration (Wilcoxon matched-pair test P < 0.001) and efavirenz/8-hydroxyefavirenz ratio (P < 0.001) by 19 and 32%, respectively, at week 16 as compared with week 4. The proportion of patients with efavirenz concentration <1 µg/ml at week 16 was higher by 67, 25, and 5% in CYP2B6*1/*1, *1/*6, and *6/*6 genotypes, respectively. The defined therapeutic range based on observed plasma concentrations is affected by the time point of sampling and the CYP2B6 genotype. The effect of efavirenz autoinduction on reducing plasma exposure continues up to week 16 and predominantly affects CYP2B6 extensive metabolizers. Among CYP2B6 slow metabolizers, the presence of a CYP3A5 genotype allele is associated with greater effects of efavirenz autoinduction on plasma concentrations of the drug. The cumulative induction may influence the long-term antiretroviral therapy outcome, particularly in CYP2B6*1 carriers.
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Ghofrani H, Distler O, Gerhardt F, Gorenflo M, Grünig E, Haefeli W, Held M, Hoeper M, Kähler CM, Kaemmerer H, Klose H, Köllner V, Kopp B, Mebus S, Meyer A, Miera O, Pittrow D, Riemekasten G, Rosenkranz S, Schranz D, Voswinckel R, Olschewski H. Therapie der pulmonal arteriellen Hypertonie (PAH). Dtsch Med Wochenschr 2010; 135 Suppl 3:S87-101. [DOI: 10.1055/s-0030-1263316] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Seidling HM, Schmitt SPW, Bruckner T, Kaltschmidt J, Pruszydlo MG, Senger C, Bertsche T, Walter-Sack I, Haefeli WE. Patient-specific electronic decision support reduces prescription of excessive doses. Qual Saf Health Care 2010; 19:e15. [PMID: 20427312 DOI: 10.1136/qshc.2009.033175] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
OBJECTIVES Prescription of excessive doses is the most common prescription error, provoking dose-dependent adverse drug reactions. Clinical decision support systems (CDSS) can prevent prescription errors especially when mainly clinically relevant warnings are issued. We have built and evaluated a CDSS providing upper dose limits personalised to individual patient characteristics thus guaranteeing for specific warnings. METHODS For 170 compounds, detailed information on upper dose limits (according to the drug label) was compiled. A comprehensive software-algorithm extracted relevant patient information from the electronic chart (eg, age, renal function, comedication). The CDSS was integrated into the local prescribing platform for outpatients and patients at discharge, providing immediate dosage feedback. Its impact was evaluated in a 90-day intervention study (phase 1: baseline; phase 2: intervention). Outcome measures were frequency of excessive doses before and after intervention considering potential induction of new medication errors. Moreover, predictors for alert adherence were analysed. RESULTS In phase 1, 552 of 12,197 (4.5%) prescriptions exceeded upper dose limits. In phase 2, initially 559 warnings were triggered (4.8%, p=0.37). Physicians were responsive to one in four warnings mostly adjusting dosages. Thus, the final prescription rate of excessive doses was reduced to 3.6%, with 20% less excessive doses compared with baseline (p<0.001). No new manifest prescription errors were induced. Physicians' alert adherence correlated with patients' age, prescribed drug class, and reason for the alert. CONCLUSION During the 90-day study, implementation of a highly specific algorithm-based CDSS substantially improved prescribing quality with a high acceptance rate compared with previous studies.
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Bertsche T, Bertsche A, Krieg EM, Kunz N, Bergmann K, Hanke G, Hoppe-Tichy T, Ebinger F, Haefeli WE. Prospective pilot intervention study to prevent medication errors in drugs administered to children by mouth or gastric tube: a programme for nurses, physicians and parents. Qual Saf Health Care 2010; 19:e26. [PMID: 20378618 DOI: 10.1136/qshc.2009.033753] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
BACKGROUND Drug administration in children is an error-prone task for nurses and parents because individual dose adjustment is often necessary, and suitable formulations for children are frequently lacking. Hence, in the absence of measures for their prevention, medication errors are likely to occur. OBJECTIVE To assess the error prevalence in drug administration by mouth or gastric tube before and after implementing a programme for quality improvement for nurses and parents. DESIGN, SETTING AND PARTICIPANTS Prospective, two-period cohort intervention study on a paediatric neurology ward of a university hospital where drug administration procedures of nurses and parents were consecutively monitored during the routine drug administration hours. MAIN OUTCOMES MEASURE Prevalence of administration errors before and after implementing instructions for appropriate drug administration, and a teaching and training programme supported by information pamphlets. RESULTS Altogether, 1164 predefined administration tasks were assessed, 675 before and 489 after the intervention. Of these, 95.7% (after the INTERVENTION 92.6%) were performed by nurses. Errors addressed by the intervention were reduced from 261/646 tasks (40.4%) to 36/453 (7.9%, p<0.001) in nurses and from 28/29 (96.6%) to 2/36 (5.6%, p<0.001) in parents. Errors in predefined categories concerning tablet dissolution, tablet storage, oral liquids, tablet splitting, administration by gastric tube and others were all considerably less frequent after the intervention (each p<0.001). CONCLUSION Errors of drug administration by mouth and gastric tube represent a considerable and often neglected drug-related problem in paediatric inpatients. Targeted quality-improvement programmes can substantially and rapidly reduce error prevalence. Appropriate teaching and training of both nurses and parents supported by pamphlets was a highly efficient way to reduce error prevalence.
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Hafner V, Jäger M, Matthée AK, Ding R, Burhenne J, Haefeli WE, Mikus G. Effect of simultaneous induction and inhibition of CYP3A by St John's Wort and ritonavir on CYP3A activity. Clin Pharmacol Ther 2009; 87:191-6. [PMID: 19924124 DOI: 10.1038/clpt.2009.206] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We aimed to assess the effect of coadministration and withdrawal of a potent cytochrome P450 3A (CYP3A) inhibitor (ritonavir) and a potent CYP3A inducer (St John's wort) on CYP3A enzyme activity in an open, fixed-sequence study design. We investigated the pharmacokinetics of midazolam: (i) at baseline, (ii) after a single dose of either St John's wort or ritonavir (each n = 6), (iii) after 14 days of coadministration of ritonavir (300 mg b.i.d.) and St John's wort (300 mg t.i.d.), and (iv) at 2 days after cessation of both St John's wort and ritonavir. Combined administration of inducer and inhibitor resulted in a predominance of enzyme inhibition: coadministration of St John's wort and ritonavir with intravenous administration of midazolam resulted in an increase in the area under the plasma concentration-time curve (AUC)(0-8 h) of midazolam to 180% of baseline value, whereas with orally administered midazolam, the AUC(0-6 h) increased to 412% of baseline value (P < 0.05 for each). After cessation of the coadministered drugs, the AUC(0-6 h) of orally administered midazolam decreased to 6% of the level observed during combined administration, and the AUC(0-8 h) of intravenously administered midazolam decreased to 33% of the values observed during combined administration (P < 0.001 for each). Induction may be unmasked after the withdrawal of a combination of a potent CYP3A inhibitor and a potent CYP3A inducer, leading to substantial drops in drug exposure of CYP3A substrates. This may require substantial dose adjustments, particularly of orally administered drugs.
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Mahler C, Jank S, Hermann K, Haefeli WE, Szecsenyi J. [Information on medications - How do chronically ill patients assess counselling on drugs in general practice?]. Dtsch Med Wochenschr 2009; 134:1620-4. [PMID: 19650022 DOI: 10.1055/s-0029-1233990] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
BACKGROUND AND OBJECTIVE Patients with chronic disease have to rely on safe and efficacious drug treatment. They therefore need individual information on their medicaton, in which counselling within the setting of general practice plays a pivotal role. However, information that seems to be relevant from the doctor's point of view is not necessarily consistent with the information patients consider to be necessary. The question was addressed in this study on to what extent patients are satisfied with the information they have received on their medication in general practice? METHODS A standardized questionnaire consisting of the SIMS-D (German version of the Satisfaction with Information about Medicines Scale) and MARS-D (German version of the Medication Adherence Report Scale) was sent to 834 chronically ill patients between March 2007 and April 2008. RESULTS Patients felt quite satisfied with the information they received on "action and usage" of medication (mean 6.95; range 0 - 9). They were not quite so satisfied with the information they received on "potential problems of medication". Self-reported adherence showed a high mean of 23.6 (range 5 - 25). Less than half of the doctors (43.6 %) inquired "always" or "often" whether patients were taking any other drugs than those prescribed. CONCLUSION Patients wish to have more information on potential drug-related problems. More attention needs to be given to a structured review of drugs prescribed in general practice.
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Bertsche T, Kaltschmidt J, Haefeli WE. [Patient safety based on computer-assisted drug therapy. Electronic check-up of the patient]. Internist (Berl) 2009; 50:748-56. [PMID: 19430754 DOI: 10.1007/s00108-009-2398-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Patients in internal medicine frequently experience adverse drug events. Many of those events, however, are avoidable because they are caused by medication errors, which are particularly frequent in drug prescribing. Therefore, practical concepts are needed to make the rapidly growing knowledge on drugs available already during prescription. But also when deviations from standards are intended access to up-to-date information is required. Computer-based systems can offer support for prescribing clinicians to meet these claims and thus improve the quality of pharmacotherapy. To reach this goal, such systems have to be interlinked among each other and with systems of primary, secondary, and tertiary care. They must be based on scientific published evidence and should consider as many factors as possible for individualization of drug therapy. Individualization and focusing on relevant information are prerequisites to prevent inappropriate alerts (over-alerting) and thus to increase acceptance in practical use.
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Haefeli W. Medizinische Probleme und
Risiken bei der rabattvertragsgerechten Umstellung von
Inhalatoren in Deutschland – Erwiderung. Dtsch Med Wochenschr 2008. [DOI: 10.1055/s-0028-1082817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Pruszydlo MG, Quinzler R, Kaltschmidt J, Haefeli WE. [Medical problems and risks of switching drugs according to legal requirements of drug discount contracts in Germany]. Dtsch Med Wochenschr 2008; 133:1423-8. [PMID: 18592450 DOI: 10.1055/s-2008-1081094] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
INTRODUCTION Since 2007 German health insurance funds may conclude discount contracts with pharmaceutical companies for individual drugs. According to German legislation pharmacies are liable to preferentially dispense these drugs to patients of the respective funds if the prescribed drug is identical regarding active ingredient, strength, package size, and route of administration, and is approved for the same indication. We aimed to assess the number and nature of clinically relevant differences between prescribed drug and its legal alternatives. METHODS Using databases and expert systems of the drug information system AiD KLINIK we evaluated all 258 412 exchangeable drug pairs of the German market currently regulated by discount contracts. RESULTS 15,7 % of the drug pairs differed in dosage, in one quarter each colour or shape was significantly different, and in roughly 3 % the size of the substituted drug differed by more than 50 %. In 9,43 % splitting characteristics of solid oral doses differed and in 1,87 % the substituted drug contained additives with allergenic potential not present in the primarily selected drug. On average 0,44 clinically relevant differences could be calculated in each substitution. CONCLUSION This study has revealed that current legal provision ignore important medical criteria of the substitution process including individual risks (e. g. allergies). Patients will have to change the drug application process and will therefore need appropriate information and training. All these differences between substitutional drug pairs should already be known when prescribing so as to maintain patient safety in the face of this merely cost-saving measure.
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Quinzler R, Schmitt SPW, Szecsenyi J, Haefeli WE. Optimizing information on drug exposure by collection of package code information in questionnaire surveys. Pharmacoepidemiol Drug Saf 2007; 16:1024-30. [PMID: 17457950 DOI: 10.1002/pds.1406] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
PURPOSE The thorough analysis of special drug characteristics requires information on the specific brand of a drug. This information is often not sought in pharmacoepidemiologic surveys although in many countries packages are labelled with an unequivocal code (in Germany called Pharmazentralnummer (PZN)). We aimed to assess the benefit and quality of PZN information collected in self-completed questionnaires. METHODS We performed a survey in 905 ambulatory patients who were asked to list brand name, strength, and the PZN of all drugs they were taking. RESULTS The medication list was completed by 97.5% (n = 882) of the responding patients (mean age 67.3 years). Altogether 5543 drugs (100%) were mentioned in the questionnaires and for 4230 (76.3%) the exact drug package could be allocated on the basis of the PZN. When PZN was considered in addition to the drug name the quality of drug coding was significantly improved (p < 0.001) with regard to the allocation of drug package (74% versus 2%), brand (90% versus 70%), and strength (96% versus 86%). The time needed for drug coding was three times shorter. CONCLUSIONS The high response rate and high fraction of correct PZN indicate that the collection of package code information is a valuable method to achieve more accurate drug data in questionnaire surveys and to facilitate the drug coding procedure.
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Rengelshausen J, Göggelmann C, Burhenne J, Riedel KD, Mikus G, Walter-Sack I, Haefeli WE. Reduction in non-glomerular renal clearance of the caffeine metabolite 1-methylxanthine by probenecid. Int J Clin Pharmacol Ther 2007; 45:431-7. [PMID: 17725176 DOI: 10.5414/cpp45431] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
OBJECTIVE Urinary caffeine metabolic ratios used to quantify the activity of numerous drug-metabolizing enzymes are an established component of cocktail approaches for metabolic phenotyping. Because in vitro evidence suggests that 1-methylxanthine (1-MX), a major caffeine metabolite, is actively secreted into urine by organic anion transporters (hOATs), coadministration of renal hOAT inhibitors like probenecid may impair these procedures. METHODS In a randomized, placebo-controlled, double-blind crossover design, single oral doses of 300 mg caffeine with oral coadministration of placebo or 500 mg probenecid 3 times daily for 2 days were administered to 7 healthy men. The plasma and urine concentrations of caffeine and its major metabolites 1,7-dimethylxanthine (1,7-DMX) and 1-MX were determined by high-performance liquid chromatography. RESULTS Coadministration of probenecid resulted in a 34% reduction of the renal clearance of 1-MX (mean +/- SD 190 +/- 42 versus 290 +/- 83 ml min(-1), 95% CI on difference 0.2, 200, p = 0.04) with a 41% reduction in its estimated non-glomerular clearance. The renal clearances of caffeine and 1,7-DMX and the area under the plasma concentration-time curves of all substances were not significantly changed. CONCLUSIONS 1-MX undergoes renal tubular secretion which is substantially reduced by probenecid, possibly due to inhibition of renal hOATs. This inhibition may explain the influence of probenecid on urinary caffeine metabolic ratios and, thus, its impact on the assessment of enzyme activities. It also suggests that 1-MX might serve as a model substrate for the renal tubular transport of organic anions.
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Quinzler R, Szecsenyi J, Haefeli WE. Tablet splitting: patients and physicians need better support. Eur J Clin Pharmacol 2007; 63:1203-4. [PMID: 17899044 DOI: 10.1007/s00228-007-0382-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Seidling HM, Al Barmawi A, Kaltschmidt J, Bertsche T, Pruszydlo MG, Haefeli WE. Detection and prevention of prescriptions with excessive doses in electronic prescribing systems. Eur J Clin Pharmacol 2007; 63:1185-92. [PMID: 17786416 DOI: 10.1007/s00228-007-0370-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2007] [Accepted: 08/07/2007] [Indexed: 01/26/2023]
Abstract
INTRODUCTION Dose dependent adverse drug reactions are often caused by prescribing errors ignoring upper dose limits. Thus, computerised physician order entry incorporating maximum recommended therapeutic doses (MRTDs) might reduce prescriptions of excessive doses. We evaluated the suitability of MRTD information as published in the Summary of Product Characteristics (SPC) (MRTD(SPC)) or by the US Food and Drug Administration (MRTD(FDA)) and the value of Defined Daily Doses (DDD, World Health Organisation) as knowledge bases for an alerting system. METHODS In a large set of critical-dose drugs (N = 140) we compared MRTD(FDA) and DDD values with the corresponding German MRTD(SPC). We then retrospectively assessed a set of 633 electronically prescribed drugs (EPDs) issued at a university hospital and calculated prescription rates of excessive doses. RESULTS MRTD(FDA) was similar to MRTD(SPC) in 37% (N = 140), higher in 32%, and lower in 31% of drugs. On average, available DDD values (N = 129) were 1.6 times lower than MRTD(SPC), with 64% being lower, 33% similar, and 3% larger than MRTD(SPC). Prescription rates of excessive doses according to MRTD(FDA) were 2.5-fold higher (6.1%) than according to MRTD(SPC) (2.5%) (p < 0.01). However, only one in four EPDs categorised as overdosed according to MRTD(FDA) exceeded MRTD(SPC), and MRTD(FDA) values were available only for 67% of all assessed EPDs. CONCLUSION Our study revealed a remarkable number of prescriptions with doses exceeding approved limits. Their prevention appears feasible but the choice of an appropriate database for MRTDs is essential, and differences between available information sources are large.
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Josephson F, Allqvist A, Janabi M, Sayi J, Aklillu E, Jande M, Mahindi M, Burhenne J, Bottiger Y, Gustafsson LL, Haefeli WE, Bertilsson L. CYP3A5 genotype has an impact on the metabolism of the HIV protease inhibitor saquinavir. Clin Pharmacol Ther 2007; 81:708-12. [PMID: 17329995 DOI: 10.1038/sj.clpt.6100117] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
CYP3A is the main enzyme subfamily involved in the metabolism of the HIV protease-inhibitor saquinavir. We hypothesized that individuals homozygous for CYP3A5*1 might have a higher oral clearance of saquinavir, compared with subjects lacking functional CYP3A5 alleles. A single-dose pharmacokinetic trial of saquinavir soft gel capsules, 1,200 mg, was performed in 16 black Tanzanian healthy volunteers with two functional CYP3A5 alleles (*1/*1) and in 18 volunteers without functional CYP3A5 alleles (both alleles being either *3, *6, or *7). The median area under the plasma concentration-time curve (AUC)0-24 reached among subjects with two functional alleles was 1,410 ng h/ml (interquartile range (IQR) 826-1,929), whereas it was 2,138 ng h/ml (IQR 1,380-3,331) in subjects without (P=0.0533, Mann-Whitney U-test). The median ratio of saquinavir over its M2 plus M3 hydroxy metabolites in urine was 64 (IQR 52-73) in subjects with two functional alleles, whereas it was 145 (IQR 89-181) in those without (P=0.000078, Mann-Whitney U-test). In conclusion, saquinavir is metabolized by CYP3A5. The median AUC0-24 for saquinavir among individuals with two functional CYP3A5 alleles was 34% lower than among those with no functional alleles. To clarify the clinical importance of the CYP3A5 polymorphism, further studies should be conducted on saquinavir, dosed to steady state, in the presence of ritonavir boosting.
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Abstract
Ein 64-jähriger Patient mit gut eingestellter essentieller Hypertonie berichtet überzeugend vom Therapieerfolg mit Yohimbin in der Akutbehandlung seiner erektilen Dysfunktion. Er wünscht die Verschreibung dieser Substanz, wovon wiederum sein Arzt nicht begeistert ist, da Akuteffekte dieser Behandlung ungewöhnlich sind und die Blockade von α2-adrenergen Rezeptoren den Blutdruck erhöhen kann. Sie einigen sich auf die Objektivierung von Wirksamkeit oder Versagen von Yohimbin in einer experimentellen Untersuchung nach einem Single Case Randomized Trial Design, also einer kontrollierten Versuchsanordnung in einem Einzelpatienten mit doppelblinder Durchführung. Der zehnmalige Vergleich von Placebo und oralem Yohimbin ließ keinen Unterschied erkennen und verhinderte, dass der Patient mit einer potenziell schädlichen Arzneimittel-Kombination exponiert wurde.
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Quinzler R, Gasse C, Schneider A, Kaufmann-Kolle P, Szecsenyi J, Haefeli WE. The frequency of inappropriate tablet splitting in primary care. Eur J Clin Pharmacol 2006; 62:1065-73. [PMID: 17024485 DOI: 10.1007/s00228-006-0202-3] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2006] [Accepted: 08/16/2006] [Indexed: 10/24/2022]
Abstract
INTRODUCTION We assessed the frequency and determinants of tablet splitting in primary care in Germany and evaluated the quality of information on divisibility in the Summary of Product Characteristics (SPCs) and in the Package Leaflet (PL) as legal sources of information for health care providers and patients. METHODS We performed a cross-sectional questionnaire survey among patients of 59 general practitioners in the German Federal State Saxony-Anhalt in 2005 in order to collect detailed information on all drugs of patients maintained on more than three drugs. RESULTS The response rate was 82.1% (n=905) and 3,158 drugs (tablets and dragées) were included in the analyses. Of all drugs, 24.1% were split (762 of 3,158): 8.7% of all split tablets were unscored (66 of 762) and 3.8% of all split tablets were not allowed to be split (29 of 762). Tablets of the higher price categories and higher strengths were twice as likely to be split. Only 22.5% of the SPCs (9 of 40) of the split unscored tablet brands contained explicit information on divisibility and only 36.4% of the PLs (8 of 22) of the split brands that were not allowed to be split stated that splitting was not appropriate. CONCLUSION The splitting of tablets in primary care is a frequent habit likely driven by medical and economic considerations. Almost 1% of all tablets are split that must not be fragmented. However, the SPC and PL provide only limited information on divisibility stressing the need to improve this information promptly to avoid medication errors.
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Haefeli WE. [Drug administration errors--what information is required to enable patients to safely take their drugs?]. THERAPEUTISCHE UMSCHAU 2006; 63:363-5. [PMID: 16841570 DOI: 10.1024/0040-5930.63.6.363] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
More than 100 different routes of drug administration are known for which highly specialised galenic formulations and sophisticated containers and application devices have been developed. Consequently substantial knowledge is required to use them in a proper and most successful way. The trend of moving the responsibility for drug application to patients and care givers necessitates their appropriate and comprehensive information to enable them to administer medication safely, skilfully, and correctly. This also includes practical skills for instance to open blisters and containers, to split tablets when needed, and to inhale, inject, or ingest the drugs. This article compiles the areas of information which should be covered, communicated, and checked by the prescribing physician and the dispensing pharmacist to maximise the patients' odds for a successful therapy.
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Abstract
Knapp ein Drittel der ambulanten Patienten teilen ihre Tabletten vor der Einnahme. Diese gängige Praxis birgt, neben etlichen Vorteilen, allerdings auch einige Risiken für die Arzneimitteltherapie. Vor allem ältere Patienten sind häufig nicht in der Lage Tabletten exakt zu teilen und die unsachgemäße Teilung z.B. von Retardpräparaten kann zu einer Überdosierung führen. Ob eine Tablette geteilt werden darf, hängt im Wesentlichen von den Wirkstoffeigenschaften, der Galenik, der Form der Tablette und der Beschaffenheit der Bruchkerbe ab. Darüber hinaus muss gesichert sein, dass der Patient über die erforderliche Bereitschaft und Fingergeschicklichkeit verfügt, seine Tabletten zu teilen, um die Compliance nicht zu beeinträchtigen. Nicht zuletzt muss der Patient über die richtige Teilungstechnik informiert sein, damit beim Teilen zwei gleichgroße Bruchstücke entstehen und die Wirksamkeit der Therapie nicht gefährdet wird.
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Bertsche T, Haas M, Oberwittler H, Haefeli WE, Walter-Sack I. Arzneimittel in Schwangerschaft und Stillzeit. Dtsch Med Wochenschr 2006; 131:1016-22. [PMID: 16673226 DOI: 10.1055/s-2006-939888] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
BACKGROUND AND OBJECTIVE In selecting drugs for treatment during pregnancy and breastfeeding it is essential to be certain of their safety. But categories are lacking that systematically relate the current state of knowledge of individual substances--rather than just drug classes--to each trimester of pregnancy. As such a stratification of risk would be helpful, it was the aim of this study to propose a new and more differentiated classification. METHODS Internationally available literature and electronic data bases providing details on adverse effects of individual drugs during pregnancy and breastfeeding as well as summaries of product characteristics of the drugs served as comprehensive sources of information. Account was taken of compound-specific data on toxicity during the reproductive and developmental stages, genotoxicity and carcinogenicity (in animals and in-vitro experiments) and drug-specific experience as documented in women during pregnancy and breastfeeding. RESULTS A new risk classification and appropriate recommendations for clinical management were developed to ensure the safety of drugs given during pregnancy and breastfeeding, taking into account the varying risks during the three trimesters of pregnancy and the perinatal period. Antibiotics were selected as a model for drugs in general and classified according to the new system. CONCLUSION The proposed new classification of risk makes it possible to select safe agents in the treatment of pregnant and/or breastfeeding women. It is based on the current state of knowledge about a particular substance, also in relationship to the developmental phase of the breastfed child.
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Knaup P, Pilz J, Kaltschmidt J, Ludt S, Szecsenyi J, Haefeli WE. Standardized documentation of drug recommendations in discharge letters--a contribution to quality management in cooperative care. Methods Inf Med 2006; 45:336-42. [PMID: 16964347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
OBJECTIVES To analyze the necessity and potential usefulness of a computerized physician order entry (CPOE) system in supporting the writing of pharmacotherapeutic recommendations in discharge letters. METHODS Systematic analysis of drug recommendations in discharge letters of a hospital providing tertiary care, structured interviews with in-hospital prescribers, and focus groups with general practitioners who admit patients to this hospital. RESULTS We analyzed 1800 randomly selected discharge letters, 1205 of which contained pharmacotherapeutic recommendations. The frequencies, structure, and quality of these recommendations varied considerably between departments. Nearly 16% of the recommendations contained both proprietary (brand) and non-proprietary names (active ingredient). Interviewed clinicians expressed interest in CPOE systems that check for contraindications and interactions between drugs, suggest cheaper products, and automatically insert active ingredients when omitted. The focus group sessions confirmed that the pharmacotherapeutic recommendations in current discharge letters do not effectively support daily clinical practice. CONCLUSIONS Documenting active ingredients as well as brand names in drug therapy recommendations is currently not part of clinical practice. Computerized decision support can help to optimise the structure and communication of therapeutic information across interfaces and can be a quality factor with considerable influence on process quality, outcome quality, and costs of cooperative patient care.
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