Herb-drug interactions: a literature review

Herbs are often administered in combination with therapeutic drugs, raising the potential of herb-drug interactions. An extensive review of the literature identified reported herb-drug interactions with clinical significance, many of which are from case reports and limited clinical observations.
Cases have been published reporting enhanced anticoagulation and bleeding when patients on long-term warfarin therapy also took Salvia miltiorrhiza (danshen). Allium sativum (garlic) decreased the area under the plasma concentration-time curve (AUC) and maximum plasma concentration of saquinavir, but not ritonavir and paracetamol (acetaminophen), in volunteers. A. sativum increased the clotting time and international normalised ratio of warfarin and caused hypoglycaemia when taken with chlorpropamide. Ginkgo biloba (ginkgo) caused bleeding when combined with warfarin or aspirin (acetylsalicylic acid), raised blood pressure when combined with a thiazide diuretic and even caused coma when combined with trazodone in patients. Panax ginseng (ginseng) reduced the blood concentrations of alcohol (ethanol) and warfarin, and induced mania when used concomitantly with phenelzine, but ginseng increased the efficacy of influenza vaccination. Scutellaria baicalensis (huangqin) ameliorated irinotecan-induced gastrointestinal toxicity in cancer patients.
Piper methysticum (kava) increased the 'off' periods in patients with parkinsonism taking levodopa and induced a semicomatose state when given concomitantly with alprazolam. Kava enhanced the hypnotic effect of alcohol in mice, but this was not observed in humans. Silybum marianum (milk thistle) decreased the trough concentrations of indinavir in humans. Piperine from black (Piper nigrum Linn) and long (P. longum Linn) peppers increased the AUC of phenytoin, propranolol and theophylline in healthy volunteers and plasma concentrations of rifamipicin (rifampin) in patients with pulmonary tuberculosis. Eleutheroccus senticosus (Siberian ginseng) increased the serum concentration of digoxin, but did not alter the pharmacokinetics of dextromethorphan and alprazolam in humans. Hypericum perforatum (hypericum; St John's wort) decreased the blood concentrations of ciclosporin (cyclosporin), midazolam, tacrolimus, amitriptyline, digoxin, indinavir, warfarin, phenprocoumon and theophylline, but did not alter the pharmacokinetics of carbamazepine, pravastatin, mycophenolate mofetil and dextromethorphan. Cases have been reported where decreased ciclosporin concentrations led to organ rejection. Hypericum also caused breakthrough bleeding and unplanned pregnancies when used concomitantly with oral contraceptives. It also caused serotonin syndrome when used in combination with selective serotonin reuptake inhibitors (e.g. sertraline and paroxetine).
In conclusion, interactions between herbal medicines and prescribed drugs can occur and may lead to serious clinical consequences. There are other theoretical interactions indicated by preclinical data. Both pharmacokinetic and/or pharmacodynamic mechanisms have been considered to play a role in these interactions, although the underlying mechanisms for the altered drug effects and/or concentrations by concomitant herbal medicines are yet to be determined. The clinical importance of herb-drug interactions depends on many factors associated with the particular herb, drug and patient. Herbs should be appropriately labeled to alert consumers to potential interactions when concomitantly used with drugs, and to recommend a consultation with their general practitioners and other medical carers.

The impact of obesity on drug prescribing in primary care

Background

Healthcare costs attributable to obesity have previously involved estimations based on costs of diseases commonly considered as having obesity as an underlying factor.

Aim

To quantify the impact of obesity on total primary care drug prescribing.

Design of study

Review of computer generated and handwritten prescriptions to determine total prescribing volume for all drug classes.

Setting

Twenty-three general practice surgeries in the UK.

Method

Stratified random selection of 1150 patients who were obese (body mass index [BMI]>30 kg/m2) and 1150 age- and sex-matched controls of normal weight (BMI 18.5–<25 kg/m2). Retrospective review of medical records over an 18-month period.

Results

A higher percentage of patients who were obese, compared with those of normal weight, were prescribed at least one drug in the following disease categories: cardiovascular (36% versus 20%), central nervous system (46% versus 35%), endocrine (26% versus 18%), and musculoskeletal and joint disease (30% versus 22%). All of these categories had a P-value of <0.001. Other categories, such as gastrointestinal (24% versus 18%), infections (42% versus 35%), skin (24% versus 19%) had a P-value of <0.01, while respiratory diseases (18% versus 21%) had a P-value of <0.05. Total prescribing volume was significantly higher for the group with obesity and was increased in the region of two- to fourfold in a wide range of prescribing categories: ulcer healing drugs, lipid regulators, β-adrenoreceptor drugs, drugs affecting the rennin angiotensin system, calcium channel blockers, antibacterial drugs, sulphonylureas, biguanides, non-steroidal anti-inflammatories (NSAIDs) (P<0.001) and fibrates, angiotensin II antagonists, and thyroid drugs (P<0.05). The main impact on prescribing volumes is from numbers of patients treated, although in some areas there is an effect from greater dosage or longer treatment in those who are obese including calcium channel blockers, antihistamines, hypnotics, drugs used in the treatment of nausea and vertigo, biguanides, and NSAIDs (P<0.05) reflected in significantly increased defined daily dose prescribing.

Consumo de medicamentos em região do Estado de São Paulo (Brasil), 1985

Com o objetivo de avaliar as características do consumo de medicamentos na população urbana de Araraquara, SP, Brasil, foram coletados dados, por meio de entrevistas domiciliares, de uma amostra da população que consumiu pelo menos um medicamento nos quinze dias que antecederam a data da entrevista. O estudo foi realizado no período de agosto a setembro de 1985. Verificou-se que 42,1% dos medicamentos utilizados foram adquiridos sem prescrição médica. O consumo entre o sexo feminino foi maior que para o sexo masculino. Na automedicação o grupo que apresentou taxa mais elevada, segundo a faixa etária, foi o de 50 anos e mais, com 31,6%. Grande parte do consumo de medicamentos constituiu-se dos industrializados (97,6%). As prescrições médicas, feitas em consultas anteriores, e avalia das como bem sucedidas foram retomadas em situações diversas (12,0%), revelando o importante papel que o médico desempenha na formação dos critérios de escolha dos remédios utilizados nas práticas de automedicação. O farmacêutico e/ou balconista de farmácia contribui com 10,0% dos medicamentos usados que tiveram essa via de indicação. As orientações feitas por amigos, vizinhos e parentes (9,1%) revelaram intenso circuito de trocas de socializações quanto aos quadros móbidos e indicações terapêuticas.

Internet pharmacies : adding disclosure requirements would aid state and federal oversight : report to Congressional Requesters /

"GAO-01-69."

The Antibiotic Resistance and Prescribing in European Children Project: A Neonatal and Pediatric Antimicrobial Web-based Point Prevalence Survey in 73 Hospitals Worldwide

BACKGROUND: The neonatal and pediatric antimicrobial point prevalence survey (PPS) of the Antibiotic Resistance and Prescribing in European Children project (http://www.arpecproject.eu/) aims to standardize a method for surveillance of antimicrobial use in children and neonates admitted to the hospital within Europe. This article describes the audit criteria used and reports overall country-specific proportions of antimicrobial use. An analytical review presents methodologies on antimicrobial use.

METHODS: A 1-day PPS on antimicrobial use in hospitalized children was organized in September 2011, using a previously validated and standardized method. The survey included all inpatient pediatric and neonatal beds and identified all children receiving an antimicrobial treatment on the day of survey. Mandatory data were age, gender, (birth) weight, underlying diagnosis, antimicrobial agent, dose and indication for treatment. Data were entered through a web-based system for data-entry and reporting, based on the WebPPS program developed for the European Surveillance of Antimicrobial Consumption project.

RESULTS: There were 2760 and 1565 pediatric versus 1154 and 589 neonatal inpatients reported among 50 European (n = 14 countries) and 23 non-European hospitals (n = 9 countries), respectively. Overall, antibiotic pediatric and neonatal use was significantly higher in non-European (43.8%; 95% confidence interval [CI]: 41.3-46.3% and 39.4%; 95% CI: 35.5-43.4%) compared with that in European hospitals (35.4; 95% CI: 33.6-37.2% and 21.8%; 95% CI: 19.4-24.2%). Proportions of antibiotic use were highest in hematology/oncology wards (61.3%; 95% CI: 56.2-66.4%) and pediatric intensive care units (55.8%; 95% CI: 50.3-61.3%).

CONCLUSIONS: An Antibiotic Resistance and Prescribing in European Children standardized web-based method for a 1-day PPS was successfully developed and conducted in 73 hospitals worldwide. It offers a simple, feasible and sustainable way of data collection that can be used globally.

Evaluating explanations about drug prescriptions: effects of varying the nature of information about side effects and its relative position in explanations

This study evaluates computer-generated written explanations about drug prescriptions that are based on an analysis of both patient and doctor informational needs. Three experiments examine the effects of varying the type of information given about the possible side effects of the medication, and the order of information within the explanation. Experiment 1 investigated the effects of these two factors on people's ratings of how good they consider the explanations to be and of their perceived likelihood of taking the medication, as well as on their memory for the information in the explanation. Experiment 2 further examined the effects of varying information about side effects by separating out the contribution of number and severity of side effects. It was found that participants in this study did not “like” explanations that described severe side effects, and also judged that they would be less likely to take the medication if given such explanations. Experiment 3 therefore investigated whether information about severe side effects could be presented in such a way as to increase judgements of how good explanations are thought to be, as well as the perceived likelihood of adherence. The results showed some benefits of providing additional explanatory information.

Potential Drug-Drug Interactions in Prescriptions to Patients over 45 Years of Age in Primary Care, Southern Brazil

Background: Few cross-sectional studies involving adults and elderly patients with major DDIs have been conducted in the primary care setting. The study aimed to investigate the prevalence of potential drug-drug interactions (DDIs) in patients treated in primary care. Methodology/Principal Findings: A cross-sectional study involving patients aged 45 years or older was conducted at 25 Basic Health Units in the city of Maringa (southern Brazil) from May to December 2010. The data were collected from prescriptions at the pharmacy of the health unit at the time of the delivery of medication to the patient. After delivery, the researcher checked the electronic medical records of the patient. A total of 827 patients were investigated (mean age: 64.1; mean number of medications: 4.4). DDIs were identified in the Micromedex (R) database. The prevalence of potential DDIs and major DDIs was 63.0% and 12.1%, respectively. In both the univariate and multivariate analyses, the number of drugs prescribed was significantly associated with potential DDIs, with an increasing risk from three to five drugs (OR = 4.74; 95% CI: 2.90-7.73) to six or more drugs (OR = 23.03; 95% CI: 10.42-50.91). Forty drugs accounted for 122 pairs of major DDIs, the most frequent of which involved simvastatin (23.8%), captopril/enalapril (16.4%) and fluoxetine (16.4%). Conclusions/Significance: This is the first large-scale study on primary care carried out in Latin America. Based on the findings, the estimated prevalence of potential DDIs was high, whereas clinically significant DDIs occurred in a smaller proportion. Exposing patients to a greater number of prescription drugs, especially three or more, proved to be a significant predictor of DDIs. Prescribers should be more aware of potential DDIs. Future studies should assess potential DDIs in primary care over a longer period of time.

Trends in morphine prescriptions, illicit morphine use and associated harms among regular injecting drug users in Australia

This paper examines population trends in morphine prescriptions in Australia, and contrasts them with findings from annual surveys with regular injecting drug users (IDU). Data on morphine prescriptions from 1995 to 2003 were obtained from the Drug Monitoring System (DRUMS) run by the Australian Government Department of Health and Ageing. Data collected from regular IDU as part of the Australian Illicit Drug Reporting System (IDRS) were analysed (2001-2004). The rate of morphine prescription per person aged 15-54 years increased by 89% across Australia between 1995 and 2003 (from 46.3 to 85.9 mg per person). Almost half (46%) of IDU surveyed in 2004 reported illicit morphine use, with the highest rates in jurisdictions where heroin was less available. Recent morphine injectors were significantly more likely to be male, unemployed, out of treatment and homeless in comparison to IDU who had not injected morphine. They were also more likely to have injected other pharmaceutical drugs and to report injection related problems. Among those who had injected morphine recently, the most commonly reported injecting harms were morphine dependence (38%), difficulty finding veins into which to inject (36%) and scarring or bruising (27%). Morphine use and injection is a common practice among regular IDU in Australia. In some cases, morphine may be a substitute for illicit heroin; in others, it may be being used to treat heroin dependence where other pharmacotherapies, such as methadone and buprenorphine, are perceived as being unavailable or undesirable by IDU. Morphine injection appears to be associated with polydrug use, and with it, a range of problems related to drug injection. Further research is required to monitor and reduce morphine diversion and related harms by such polydrug injectors.

Aspirin and other non-steroidal anti-inflammatory drug prescriptions and survival after the diagnosis of head and neck and oesophageal cancer

Peer reviewed

Potentially Inappropriate Medications Defined by STOPP Criteria and the Risk of Adverse Drug Events in Older Hospitalized Patients

Background: Previous studies have not demonstrated a consistent association between potentially inappropriate medicines (PIMs) in older patients as defined by Beers criteria and avoidable adverse drug events (ADEs). This study aimed to assess whether PIMs defined by new STOPP (Screening Tool of Older Persons’ potentially inappropriate Prescriptions) criteria are significantly associated with ADEs in older people with acute illness.

Methods: We prospectively studied 600 consecutive patients 65 years or older who were admitted with acute illness to a university teaching hospital over a 4-month interval. Potentially inappropriate medicines were defined by both Beers and STOPP criteria. Adverse drug events were defined by World Health Organization–Uppsala Monitoring Centre criteria and verified by a local expert consensus panel, which also assessed whether ADEs were causal or contributory to current hospitalization. Hallas criteria defined ADE avoidability.Wecompared the proportions of patients taking Beers criteria PIMs
and STOPP criteria PIMs with avoidable ADEs that were causal or contributory to admission.

Results: A total of 329 ADEs were detected in 158 of 600 patients (26.3%); 219 of 329 ADEs (66.6%) were considered causal or contributory to admission. Of the 219 ADEs, 151(68.9%)considered causal or contributory to admission were avoidable or potentially avoidable. After adjusting for age, sex, comorbidity, dementia, baseline activities of daily living function, and number of medications, the likelihood of a serious avoidable ADE increased significantly when STOPP PIMs were prescribed (odds ratio, 1.847; 95% confidence interval [CI], 1.506-2.264; P.001); prescription of Beers criteria PIMs did not significantly increase ADE risk (odds ratio, 1.276; 95% CI, 0.945-1.722; P=.11).

Conclusion: STOPP criteria PIMs,unlike Beers criteria PIMs, are significantly associated with avoidable ADEs in older people that cause or contribute to urgent hospitalization.

A computerized audit of non-steroidal anti-inflammatory drug prescribing in general practice

The two group practices based in a city health centre decided to prescribe non-steroidal anti-inflammatory drugs in generic form from an agreed date. The practices' computer was used to identify the number of repeat prescriptions being issued for this group of drugs and to monitor the effectiveness of the changeover. Although both practices showed a marked increase in the level of generic prescribing there was considerable interpractice variation. Generic prescribing for one practice increased from 4% to 64% and for the other from 1% to 38% of repeat prescriptions issued for non-steroidal anti-inflammatory drugs over the study period. The reasons for this variation, the advantages of computerized audit and the problems associated with this self-imposed audit are discussed.

Outpatient prescriptions practice and writing quality in a paediatric university hospital.

BACKGROUND: The writing of prescriptions is an important aspect of medical practice. This activity presents some specific problems given a danger of misinterpretation and dispensing errors in community pharmacies. The objective of this study was to determine the evolution of the prescription practice and writing quality in the outpatient clinics of our paediatric university hospital.¦METHODS: Copies of prescriptions written by physicians were collected from community pharmacies in the region of our hospital for a two-month period in 2005 and 2010. They were analysed according to standard criteria, including both formal and pharmaceutical aspects.¦RESULTS: A total of 597 handwritten prescriptions were reviewed in 2005 and 633 in 2010. They contained 1,456 drug prescriptions in 2005 and 1,348 in 2010. Fifteen drugs accounted for 80% of all prescriptions and the most common drugs were paracetamol and ibuprofen. A higher proportion of drugs were prescribed as International Nonproprietary Names (INN) or generics in 2010 (24.7%) compared with 2005 (20.9%). Of the drug prescriptions examined, 55.5% were incomplete in 2005 and 69.2% in 2010. Moreover in 2005, 3.2% were legible only with difficulty, 22.9% were ambiguous, and 3.0% contained an error. These proportions rose respectively to 5.2%, 27.8%, and 6.8% in 2010.¦CONCLUSION: This study showed that fifteen different drugs represented the majority of prescriptions, and a quarter of them were prescribed as INN or generics in 2010; and that handwritten prescriptions contained numerous omissions and preventable errors. In our hospital computerised prescribing coupled with advanced decision support is eagerly awaited.