A dynamic calibration technique for temperature programmed desorption spectroscopy.

A novel, rapid and accurate calibration procedure as a means for quantitative gas desorption measurement by temperature programmed desorption (TPD) spectroscopy is presented. Quantitative measurement beyond the linear regime of the instrument is achieved by associating an instantaneous calibrated molar flow rate of gas to the detector response. This technique is based on fundamental methods, and is independently verified by comparison to the hydrogen desorption capacity of a known standard metal hydride with known stoichiometry. The TPD calibration procedure described here may be used for any pure gas, and the accuracy is demonstrated for the specific case of hydrogen.

Electron and hole transfer from indium phosphide quantum dots.

Electron- and hole-transfer reactions are studied in colloidal InP quantum dots (QDs). Photoluminescence quenching and time-resolved transient absorption (TA) measurements are utilized to examine hole transfer from photoexcited InP QDs to the hole acceptor N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) and electron transfer to nanocrystalline titanium dioxide (TiO2) films. Core-confined holes are effectively quenched by TMPD, resulting in a new approximately 4-ps component in the TA decay. It is found that electron transfer to TiO2 is primarily mediated through surface-localized states on the InP QDs.

Impact of drug usage review on drug utilisation.

Drug use review (DUR) programmes have been a component of efforts to improve prescribing practices in both the institutional and ambulatory care settings in various areas of the world. DUR provides the mechanism for developing standards, assessing current therapy, and implementing a specific intervention followed by reassessment of drug utilisation. A number of interventions aimed at improving drug prescribing practices have been included as components of the DUR process. At this time, face-to-face interaction with the prescriber has been shown to be the most effective intervention. However, DUR interventions have rarely been subjected to quality pharmacoeconomic evaluation. There is a need for future research to evaluate the effects of DUR programmes on overall healthcare outcomes.

Long-term use of benzodiazepines in a Swedish community: an eight-year follow-up.

Use of benzodiazepines in a Swedish community with a general population of about 20,000 was studied using data from a research registry on prescriptions. A cohort of all benzodiazepine users in 1976, aged 15-84 years, was identified and followed for 8 years with respect to continued benzodiazepine use. A strong tendency towards continuous use was observed. Nearly 70% of the cohort continued use of benzodiazepines during the first follow-up year, 56% used benzodiazepines during the second year as well. One third continued using benzodiazepines during all 8 years of follow-up. Heavy use, previous use of benzodiazepines and age were of great importance for predicting long-term use while sex and type of benzodiazepine were of minor importance. However, after 3 or 4 years of use the pattern was very much the same in all subgroups, about 90% of users continued irrespective of user characteristics.

Increased prescribing of antidepressants subsequent to beta-blocker therapy.

Using records of the Saskatchewan Prescription Drug Plan, we determined the incidence of antidepressant use (a marker for depressive symptoms) in patients who received beta-blockers or other treatments for chronic diseases (diuretics, antihypertensives, and hypoglycemics) during 1984, but not in the previous 6 months. Antidepressants initiated within 12 months after the study drug were counted. Of the 3218 new beta-blocker users, 6.4% received concurrent prescriptions (ie, within 34 days) for an antidepressant and beta-blocker. Only 2.8% of the reference group (no study drug use) received an antidepressant. A greater proportion of patients prescribed propranolol (9.5%) received an antidepressant than those prescribed other "lipophilic" (3.9%) or "hydrophilic" (2.5%) beta-blockers. Incidence ratios for propranolol revealed the overall risk antidepressant use was 4.8 (95% confidence interval [CI], 4.1 to 5.5) times that of the reference group and 2.1 (95% CI, 1.7 to 2.5) times that of all other study drug users. For propranolol, relative risk of antidepressant use (drug/reference group) varied with age and was greatest in the 20- to 39-year-old group (17.2; 95% CI, 13.7 to 21.5).

The Saskatchewan program for rational drug therapy: effects on utilization of mood-modifying drugs.

In 1978, the Joint Committee on Drug Utilization (JCDU) was appointed by the Saskatchewan Minister of Health to identify and analyze concerns related to drug use and to recommend appropriate methods for dealing with such concerns. Emphasis was placed on the quality of healthcare in the province and on the provision of information as a basis for education of the public and health professionals. Since 1978, 14 committee reports providing drug utilization statistics and specific recommendations for improving drug therapy have been distributed to Saskatchewan health professionals. The main focus has been on utilization studies of "mood-modifying" drugs (analgesics, minor and major tranquilizers, sedative/hypnotics, stimulants, and antidepressants). The JCDU initiated a program whereby drug profiles of certain patients were released to selected health professionals. Individuals who received daily doses in excess of JCDU guidelines for mood-modifying drugs over a three-month period were categorized as extreme users. Patient medication profiles of their drug use were forwarded on a quarterly basis to physicians who prescribed and the primary pharmacy that dispensed mood-modifying drugs to these patients. From the time of the first profiles (October-December 1979) until 1983, there was a 15 percent decrease in the number of extreme users. Between 1977 and 1985, there was a decrease in the percentage of the overall population receiving any prescriptions for these drugs (from 20 to 17.4 percent).

Evaluation of a computer-assisted medication refill reminder system for improving patient compliance.

Computer-generated refill reminder notices were mailed to patients receiving continual medication for cardiovascular diseases to measure improved compliance and to discover whether a computer-assisted program was economically viable. Guidelines were established to define compliance. A computer-assisted compliance intervention program did not significantly improve the rate at which patients had their prescriptions filled "on time" and the mean compliance rate for both experimental and control groups was greater than 79%. Also discussed were cost and compliance strategy implications and the receptiveness of patients to the reminder program.

Clinical pharmacokinetics of non-steroidal anti-inflammatory drugs.

The number of non-steroidal anti-inflammatory drugs (NSAIDs) available for clinical use has dramatically increased during the last decade. As a general rule, NSAIDs are well absorbed from the gastrointestinal tract, with the exception of aspirin (and possibly diclofenac, tolfenamic acid and fenbufen) which undergoes presystemic hydrolysis to form salicylic acid. Concomitant administration of NSAIDs with food or antacids may in some cases lead to delayed or even reduced absorption. The NSAIDs are highly bound to plasma proteins (mainly albumin), which limits their body distribution to the extracellular spaces. Apparent volumes of distribution of NSAIDs are, therefore, very low and usually less than 0.2 L/kg. The elimination of these drugs depends largely on hepatic biotransformation; renal excretion of unchanged drugs is usually small (less than 5% of the dose). Total body clearance is low and for most NSAIDs is less than 200 ml/min. The effect of age and disease on the disposition of NSAIDs has not been extensively studied. Due to the central role of the liver in the overall elimination of the majority of these compounds, hepatic disease will most likely lead to a significant alteration in their pharmacokinetic behaviour. NSAIDs have been reported to be involved in numerous pharmacokinetic drug interactions. Aspirin decreases the plasma concentrations of many other NSAIDs, although the clinical significance of this is uncertain. Due to the extremely high plasma protein binding of NSAIDs (around 99% in many cases), competition for the same binding sites on plasma proteins may be at least partly responsible for some interactions of NSAIDs with other highly bound drugs; however, another mechanism such as decreased metabolism or decreased urinary elimination is usually involved as well. The most important interactions with NSAIDs are those involving the oral anticoagulants and oral hypoglycaemic agents, though not all NSAIDs have been found to interact with these drugs. In clinical practice, there appear to be no clear-cut guidelines to assist the clinician in the selection of the most appropriate drug for an individual patient. The selection of an anti-inflammatory drug should be based on clinical experience, patient convenience (e.g. once or twice daily dosage schedule), side effects and cost. Since a marked interindividual variability exists in the clinical response to a given NSAID, clinicians prescribing these agents may try several of them sequentially until an adequate response is obtained.

Saskatchewan dial-access drug information service.

In September 1974 the colleges of pharmacy and medicine of the University of Saskatchewan began offering a drug information service to the pharmacists and physicians of Saskatchewan without charge. With the help of a radio-page system, calls are taken immediately by experienced pharmacists and pharmacologists. The cost of long-distance phone calls is borne by grants from the Saskatchewan medical and pharmaceutical associations. During the 1st year of operation 415 requests for information were received. Of 93 persons who called up to Feb. 28, 1975, 76% responded to an evaluation questionnaire; virtually all described the service as very valuable. The information received resulted in the alteration of drug therapy in one third of calls requesting information to assist in current treatment of a patient.