Prescribed Daily Dose Research Articles

Prescribing patterns of tricyclic and selective serotonin reuptake inhibitor antidepressants among a sample of adolescents and young adults.

There are few studies that document antidepressant prescribing in young patients. Although tricyclic antidepressants (TCAs) are considered equal in efficacy to selective serotonin reuptake inhibitors (SSRIs), the latter have an improved side effect profile. The aim of this study was to investigate the prescribing patterns of TCAs and SSRIs among adolescents and young adults, with reference to prescribing frequency, cost and dose. A retrospective drug utilization study was conducted over a 14-month period, from January 2000 to February 2001. There were 166 antidepressants prescribed to 98 adolescents and young adults. TCAs were prescribed more frequently than SSRIs, with amitryptiline and fluoxetine being the two most frequently prescribed antidepressants. Fluoxetine accounted for a higher ratio of cost to prescribing frequency than amitryptiline. Amitryptiline was issued in small quantities of tablets, resulting in a low average calculated prescribed daily dose (PDD). Duration of treatment was not considered optimal for SSRIs or TCAs. This study elicits prescribing patterns that contribute to the relative scarcity of data on antidepressant drugs for young patients.

Unita di consumo dei farmaci e valutazioni farmacoeconomiche: uso e misuso di DDD e PDD

In pharmacoeconomical evaluations the quantification of drug utilization has to be done on the basis of measurement units that allow comparisons among series of longitudinal and transversal data. The most common techniques used for the analysis and the comparison of drug utilization patterns are based either on the Defined Daily Dose (DDD), a unit system proposed by WHO’s Drug Utilization Research Group, or on the Prescribed Daily Dose (PDD), a statistical parameter obtained from the analysis of drug prescriptions. This article illustrates the meaning of the main indicators of drug consumption that can be build with these techniques, underlining their utility and limitations. The DDD is the conventionally established theoretical mean daily dose of a drug, referred to a way of administration and to its main indication. It is, therefore, a mere technical measurement unit that cannot be interpreted as mean prescribed or consumed dose, and even less as recommended dose. The PDD, on the contrary, is not a measurement unit but a statistical mean value, that expresses the central tendency of the prescription variability in a defined setting. Starting from Italian data on the consumption of wide-spread antibiotics, the use and interpretation of various indicators based on the DDDs and PDDs are discussed. The parameters derived with the DDD technique are suitable for monitoring drug utilization and pharmaceutical expenditure. The PDD method is more direct, indicates the mean quantities actually prescribed and permits the estimation of the total dose consumed per therapeutic cycle and of other clinically relevant parameters, but requires the acquisition of more data than the other technique does. It is also important to remark the fact that both methods can’t be directly used for economical evaluations trying to assess the efficiency of resource allocation, as they are not correlated to the clinical outcomes of the therapy.

Adherence to and dosing of statins differs according to apolipoprotein E-genotypes

Discontinuation and poor compliance is a major problem in long-term therapy, and in particular with cholesterol lowering drugs. Several studies have indicated that the cholesterol lowering efficacy of statins differs according to apoE genotypes. In effect LDL-cholesterol lowering capacity appears to be smaller in subjects with the ɛ4 allele. This reduced response in ɛ4 carriers may influence dosing regimens and discontinuation in daily practice. Our objective was to assess whether the use of statins in daily practice differs according to apoE genotypes. We used data from The Rotterdam Study, a population based prospective cohort study in the Netherlands, which started in 1990 and included 7,983 subjects of 55 years and older. Pharmacy records were available for approximately 99% of the cohort as of January 1, 1991. These records include the name of the drug, day of dispensing, dosage form, number of units dispensed, prescribed daily dose (PDD) and the Anatomical Therapeutic Chemical (ATC) code of the drug. During follow-up (until 31-05-2000) 1037 subjects started to use statins. We excluded 239 subjects because of missing data. We used the PDD to compare dosages of different statins. The PDD was calculated as: daily prescribed dose / standard dosage of the drug when prescribed for the main indication. The first PDD was the dose of the first statin prescription the patient received and the final PDD was the last dose that was prescribed to the patient. We used the Cox proportional hazard model to determine the rate of discontinuation in the first 3 years of statin use. We excluded subjects with the ɛ2ɛ2 genotype (n = 4) from this analysis. Subjects with the ɛ4ɛ4 genotype had a relative risk (RR) of 2.28 (95% CI 1.02, 5.12) to discontinue their statin-therapy within 3 years compared with subjects with the ɛ2ɛ3 genotype. In women this RR was 1.70 (CI 0.53, 5.42), vs 3.18 (CI 1.01, 10.03) in men. The dosage of the last prescription was significantly higher (P < 0.05) for subjects with ɛ3ɛ4 and ɛ4ɛ4 (1.16 PDD) compared with subjects with the ɛ3ɛ3 genotype (1.03 PDD). ApoE genotype is a determinant of both dosage regimens and discontinuation of statin therapy. This entails that those subjects who are genetically prone to develop hypercholesterolaemia show the highest risk of discontinuation of treatment precisely for that condition. This warrants further investigation.

Methadone prescribing to opiate addicts by private doctors: comparison with NHS practice in south east England.

To compare National Health Service (NHS) and private practice in prescribing methadone to opiate addicts. Survey of community pharmacies during 1995 (one in four random sample) and during 1997 (one in two random sample) in which data were collected on all methadone prescriptions currently being dispensed to opiate addicts. Dispensing community pharmacies in south east England. UNITS MEASURED: 829 methadone prescriptions (785 NHS and 44 private) from 1995, and 761 (703 NHS and 58 private) from 1997. (i) The prescribed daily dose of methadone; (ii) the form (oral mixture, tablets or ampoules); and (iii) the pick-up duration (daily collection of prescribed dose, through to weekly or fortnightly collection in a single pick-up). Private methadone prescriptions issued to addicts typically give twice the daily dose, are more than four times as likely to give the methadone in injectable form, and most commonly give prescriptions to be collected in a single large weekly or fortnightly installment instead of through daily dispensing, compared with NHS methadone prescriptions. The disparity between private and NHS methadone prescriptions is striking. The much higher doses, the lack of arrangements for installment collection and the frequent choice of injectable forms of methadone increase greatly the risk of abuse and diversion to the black market. Regulatory scrutiny of this private practice in the United Kingdom is currently minimal. Independent research is required to explore more fully the different nature of such private methadone prescribing.

Valutazione farmacoeconomica di una casistica di pazienti con riacutizzazione di bronchite cronica

Aim of this study is to operate a pharmaeconomical evaluation on case histories of patients affected by chronic bronchitis relapse, comparing the effectiveness of different molecules with antibiotic activity and the total cost far each considered drogo. The observational retrospective study has been conducted at the Bronchopncumology Depaliment of the E. Morelli Hospital (Reggio Calabria) on 344 patients aftècted by acute infective or chronic relapsed bronchopneumopaties between January, the 1st, 1997 and December, the 31th 1999. To avoid excessive data dispersal, the study considered only the active principles prescribed to at least 50 persons: ceftazidime, ceftriaxone, cefepime and piperacilline + tazobactam. AlI the patients have responded positively to the treatment, so the cost minimization analysis has been carried out far every dosage regimen, considering different parameters: nursing staff costs, consumable material and drug costs. The Prescribed Daily Dose (PDD) has been taken as unit of measurement for drug costs. The single adminstration cost is based on nursing costs and consumable material costs. To get the total therapy cost, it’s necessary to add the single administration drug costo. In this study, the lowest total cost is guaranteed by treatment with ceftriaxone.

Costi e profili di trattamento farmacologico nei pazienti con diabete di tipo 2: i risultati dello studio CODE-2

Objective To investigate PDDs (Prescribed Daily Doses) of ATC classes relevant to the treatment of diabetes mellitus (oral anti-diabetics, insulin, cardiovascular drugs) in different kinds of diabetic patients (complicated/not complicated, good/borderline/no glycaemic control). To estimate per patient and per population drug costs.

An approach for the estimation of drug prescribing using the defined daily dose methodology and drug dispensation data. Theoretical considerations and practical applications.

To test the hypothesis that comparison of defined daily dose (DDD) and drug user data may help to estimate drug exposure in a defined population and provide information about drug prescribing patterns. First, comparison of DDD figures with the number of apparent drug users (ADU, i.e., individuals for whom at least one prescription of the drug had been dispensed during a given time period) is demonstrated to correspond to the product of the prescribed daily dose (PDD) and the proportion of days in which the drug had been taken (days of treatment/days in a time period, D). The resulting equation (DDD/day)/ ADU in a time period = PDD x D is then applied to the analysis of different sets of drug dispensation data. Examples show that this approach may be helpful to monitor drug prescribing patterns over time. Moreover, in definite situations, it may provide reliable estimates of either PDD or D. Comparison of DDD and drug user data is suggested to be a cost-effective strategy to monitor drug prescribing patterns from an epidemiological perspective, which may be useful to researchers involved in drug utilisation studies as well as to health authorities for monitoring and regulatory purposes.

Examining the adequacy of quantities available for subsidized antidepressant prescriptions in Australia

In Australia the Pharmaceutical Benefits Scheme (PBS), a national drug insurance plan, aims to provide around a month's therapy for medication used in chronic conditions. However, there are marked differences among the most commonly used antidepressants in the number of days supply represented by the PBS maximum quantity after adjustment for the defined daily dose (DDD). The DDD is the assumed adult daily dose for a drug and is a WHO drug utilization standard. Whereas the selective serotonin re-uptake inhibitors (SSRIs) and moclobemide largely provide around a month's supply at the DDD, most tricyclic antidepressant (TCA) items provide considerably less than this. A patient tracking study was conducted to determine the average length of time between prescription re-supplies for a number of tricyclic antidepressants and newer antidepressants as a means of measuring the efficiency of PBS supply for the different classes of antidepressant. The number of days between dispensings was similar for patients no matter whether they were taking TCAs, SSRIs or moclobemide, although for the older antidepressants presumably at a much lower prescribed daily dose than the DDD. Care needs to be taken when adjusting usage with the DDD/1000/day unit of measurement in cases where the DDD does not reflect the prescribed daily dose (PDD). Copyright © 1999 John Wiley & Sons, Ltd.

Examining the adequacy of quantities available for subsidized antidepressant prescriptions in Australia.

In Australia the Pharmaceutical Benefits Scheme (PBS), a national drug insurance plan, aims to provide around a month's therapy for medication used in chronic conditions. However, there are marked differences among the most commonly used antidepressants in the number of days supply represented by the PBS maximum quantity after adjustment for the defined daily dose (DDD). The DDD is the assumed adult daily dose for a drug and is a WHO drug utilization standard. Whereas the selective serotonin re-uptake inhibitors (SSRIs) and moclobemide largely provide around a month's supply at the DDD, most tricyclic antidepressant (TCA) items provide considerably less than this .A patient tracking study was conducted to determine the average length of time between prescription re-supplies for a number of tricyclic antidepressants and newer antidepressants as a means of measuring the efficiency of PBS supply for the different classes of antidepressant. The number of days between dispensings was similar for patients no matter whether they were taking TCAs, SSRIs or moclobemide, although for the older antidepressants presumably at a much lower prescribed daily dose than the DDD. Care needs to be taken when adjusting usage with the DDD/1000/day unit of measurement in cases where the DDD does not reflect the prescribed daily dose (PDD).

An investigation into the prescribing patterns of selective serotonin re-uptake inhibitors in South Africa.

The primary aim of the study was to investigate the prescribing patterns of selective serotonin re-uptake inhibitors (SSRIs) used on a chronic basis in a defined South African patient population, and to calculate the average prescribed daily doses (PDDs) of selected SSRIs. Prescription data for 2117 patients from various medical schemes who were using antidepressant drugs on a chronic basis were analysed retrospectively. More than 70% of all the patients using antidepressants were females. The tricyclic antidepressants (TCAs) and the SSRIs accounted for approximately 75% of all the antidepressants prescribed. The average age of the patients using SSRIs was 48.1 years (SD = 13.4 years). Fluoxetine was the most frequently prescribed SSRI, accounting for 63.3% of all SSRI prescriptions and 21.9% of all antidepressant prescriptions. The average PDDs of citalopram (23.9 mg), fluoxetine (21.7 mg) and paroxetine (21.1 mg) were slightly higher than their defined daily doses (20 mg for all three drugs). The average PDD of fluvoxamine (93.5 mg) was lower than the DDD (150 mg), but was still within an acceptable dose range. It was concluded that fluoxetine was clearly the drug of choice in treating chronic depression in this patient sample, and that the PDDs used in the patient population studied were in agreement with local and internationally acceptable dosage ranges.

Local clinical guidelines: description and evaluation of a participative method for their development and implementation.

National guidelines are rarely followed by immediate change in clinical behaviour. We present our experience of an active educational method for local development and implementation of a guideline. To evaluate the effectiveness of a participative method for developing local clinical guidelines. A trial in a district of the effect of guideline development incorporating active participation of intended recipients on subsequent relevant prescribing. It was carried out in Wirral Family Health Services Authority district (the Wirral peninsula) comprising 69 general practices covering a population of 345,763. An exemplar guideline on 'hypertension in the elderly' was developed by the method described. The principal recommended drug was bendrofluazide 2.5 mg once daily. The differences in prescribed daily doses (PDD) of bendrofluazide 2.5 mg tablets per quarter per 1000 prescribing units (age-weighted population) between the intervention district and England as a whole was measured. Comparison of the intervention district with England data demonstrates a median difference of 122.49 PDD before and 206.34 PDD after guideline production, this change is statistically highly significant (Mann-Whitney two-tailed P < 0.0001; 95% CI = 36.51-104.77). Grouped regression analysis shows no significant difference (0.89) in slope gradients before guideline production (P = 0.35, 95% CI = -3.97-5.76), but the difference in slope gradients after (12.95) is statistically highly significant (P < 0.0001; 95% CI = 8.17-17.73). The data suggests that the change in clinical behaviour persisted for at least two years. Participation of intended recipient general practitioners and local specialists in the development of a guideline by an active educational method as described was followed by a favourable change in clinical behaviour which persisted for at least two years.

Analysis of total parenteral nutrition utilization in intensive-care patients

The objective of this study is to validate an all-in-one defined daily dose (DDD) methodology for studying the utilization of total parenteral nutrition (TPN) with patient-linked data. Furthermore, the utilization of TPN in intensive-care patients is described. In a prospective survey, conducted from March to August 1992 on two intensive-care units, 47 patients using TPN were followed. Adapted ratios of prescribed daily dose (PDD) and DDD for amino acids, fat emulsion, and carbohydrates were 0.76±0.22, 0.69±0.30 and 1.07±0.23 (mean±SD), respectively. The ratio of the number of TPN DDD's to the number of TPN treatment days was 0.84±0.18. The prescription rate of TPN was 19.9 DDD/100 beddays, composed of 5.9 DDD/100 beddays for amino acids, 5.8 for fat emulsion, and 8.2 (or carbohydrates. It was shown that the proposed all-in-one DDD methodology can be used to describe the utilization of TPN and its components. The DDD's for amino acids, fat emulsion, and carbohydrates are valid for use in intensive-care patients.

Metabolic Control in Diabetic Subjects in Three Swedish Areas With High, Medium, and Low Sales of Antidiabetic Drugs

The relationship between use of antidiabetic drugs and metabolic control was studied in Swedish diabetic populations in areas with high (Gotland), medium (Tierp), and low (Skellefteå) sales of antidiabetic drugs. The study population consisted of 405 drug-treated diabetic subjects aged 50-74 yr. In all three areas, glyburide comprised approximately 75% of the oral treatment. In accordance with sales, Gotland was found to be a heavy-use area, characterized by a high prevalence of insulin treatment (43%), combination therapy with sulfonylureas and biguanide (28%), and high prescribed daily doses (PDDs) of glyburide (15.5 +/- 0.8 mg) compared with other areas. In Skellefteå, 38% were on insulin, 4% were on combination therapy, and the PDD of glyburide was 7.1 +/- 0.6 mg. In Tierp, 27% were on insulin, 26% were on combination therapy, and the PDD of glyburide was 11.4 +/- 0.7 mg. In Gotland, both men and women had significantly lower HbA1c levels, regardless of treatment mode, and a tendency to be more overweight compared with the area with the least pharmacological intensity (Skellefteå). In the three diabetic populations, good metabolic control, defined as an HbA1c level of less than 7% and acceptable weight control (body mass index less than 27 for men and less than 25 for women), was achieved among only 16% in Gotland, 17% in Skellefteå, and 12% in Tierp.

Allgemeinärzte und Internisten verschreiben Psychopharmaka

An epidemiological study using data from a local German health insurance fund on the psychotropic drug prescription of physicians and the drug utilisation of their patients is presented. Taking a sample of 280 out-patients, descriptive methods are presented (defined daily dose (DDD), prescribed daily dose (PDD), active-agent-oriented classification of drugs, therapy-oriented classification of diagnoses). The following questions are answered by this study: Which patients with which indication received which dosage of which psychotropic drug for how long from which physicians? The patient-based structure of the data, taking into account the prescriptions of all physicians allows the course of therapies and the study of overall psychotropic medication. Prevalences estimates concerning the patients are also possible. Our results are compared with those of similar pharmaco-epidemiological studies; the difference in prevalence estimates, as well as advantages and possible disadvantages arising from the use of such secondary data base, are discussed.

Prescribed daily dose of phenoxymethylpenicillin in general practice.

Prescribed daily dose (PDD) of phenoxymethylpenicillin was estimated in a multipractice study in 1979 and in 1983. PDD increased from 2.08 mio IU in 1979 to 2.32 mio IU in 1983. PDD was independent of number of daily doses, and factors related to practice. Only slight variations with diagnosis and doctor's age was found.

Use of antibiotics in general practice in Denmark. Prescribed daily dose, duration of treatment and number of treatments in general practice.

Prescribed daily dose (PDD) and duration of treatment is estimated for the most commonly used antibiotics in a multipractice study. In 1979 574 general practitioners and in 1983 625 general practitioners recorded 7 681 respectively 8 182 prescriptions of antibiotics over a five-day period. PDD and the number of treatments were compared with Defined Daily Dose (DDD) and DDD/1 000 inhabitants/day from the official statistics of drug consumption. It was found that these commonly used units were rather misleading with regard to the daily dose actually prescribed and the number of treatments given in a certain period.

Patterns in drug utilization--national and international aspects: antihypertensive drugs.

There is a reasonable agreement between defined daily doses (DDDs) and prescribed daily doses (PDDs) of antihypertensive drugs, at least in Norway and Sweden. Sales and prescriptions of antihypertensive drugs in seven European countries (CSSR, Denmark, Finland, Iceland, Northern Ireland, Norway and Sweden) have increased 50 to 200% during the last 10 years. The drug statistics also illustrate marked qualitative and quantitative differences in the utilization of antihypertensive drugs between these seven European countries. Mortality in cardiovascular diseases also differs between these countries, particularly between Northern Ireland and Finland and the other countries. So do sales of alcohol and tobacco. However, none of these factors seem to co-vary with drug utilization.

A community pharmacy-based survey of antihypertensive and antidiabetic drug dosages in Northern Ireland.

International drug utilization data comparisons for antihypertensive and anti-diabetic agents based on standard daily dosage units, Defined Daily Doses (DDD), show that less of these drugs are prescribed per head of population in Northern Ireland than in Norway or Sweden. A study was designed to investigate whether actual prescribing practices in Northern Ireland might account for some of these apparent differences by comparing the average prescribed daily dose, (PDD) with the DDD for antihypertensive and antidiabetic drugs. Daily dosage information was collected on the antihypertensive and antidiabetic drugs dispensed at 47 Northern Ireland pharmacies during the month of October 1981. A high proportion (73%) of the community pharmacies randomly chosen to take part in the survey were able to record daily dosage instructions. Thirty per cent of the prescriptions monitored were ‘as directed’, but in over one-third (42%) of these cases, pharmacy staff ascertained how the drug was to be taken by questioning the recipient. For each antihypertensive and antidiabetic drug, the average prescribed daily dose (PDD) was calculated from the aggregated data. In general, the Northern Ireland PDDs were close to the Defined Daily Dose (DDD) units of international comparisons assigned to each drug. Most beta-blocking agents and other hypotensives had average prescribed daily doses that were only slightly lower than the DDDs assigned. The PDDs of all hypoglycaemic agents and insulin were marginally less than the corresponding DDDs. These results indicate that the apparent low prescribing of these drugs in Northern Ireland is not due to marked differences between assumed and actual prescribing practices.