Search PubMed⌕ Search

Biomedical subjects

D L Uden

Publications and source records attributed to D L Uden.

35 records · Page 2Linked to original sources
PubMed1984

Theophylline therapy. Titrating dosage requirements.

Theophylline has long been a cornerstone of bronchodilator therapy for asthma and chronic obstructive lung disease, but until recently its use carried the risk of serious, even fatal, toxicity. With recent advances in understanding of this drug's pharmacologic properties and pharmacokinetic characteristics, serious toxicity now can usually be avoided. The dosage requirements for theophylline demonstrate wide interpatient and intrapatient variation. Several factors responsible for this variation, most notably age, have been identified and used in definition of dosage guidelines for different patient groups. However, substantial variation still exists within these groups, necessitating measurement of serum concentration in selected patients. The measurements obtained are used to titrate the patient's dosage requirement in such a way as to maximize therapeutic response while minimizing risk of toxicity.

Administration, Oral↗
PubMed1982

Intravenous glycerol and mannitol therapy in children with intracranial hypertension.

Acute intracranial hypertension may respond to intravenous mannitol, but frequent administration can cause cerebral edema or renal problems. We evaluated the use of 20% glycerol administered intravenously as an alternative to mannitol. Intravenous glycerol and mannitol were equally effective in lowering acute elevations of intracranial pressure. The duration of effect was similar for both agents. Side effects of intravenous glycerol were related to concentration, rate, and frequency of administration. In severe encephalopathies, such as Reye syndrome, we recommend infusions of 20% glycerol or 20% mannitol at a dose of 0.5-1.0 gm per kilogram. Glycerol should be administered in 0.45% or 0.9% saline, no faster than 1.5 ml (3.3 mOsm) per minute.

Adolescent↗
PubMed1981

The effect of carbonated beverages on ipecac-induced emesis.

To determine the effect of carbonated beverages on syrup of ipecac, 24 pediatric patients were randomly administered six ounces of water or a carbonated beverage with syrup of ipecac. Changes in the abdominal girth, the volume of emesis, and time of emesis were monitored in all patients. In the carbonated beverage group a significant difference (P less than 0.05) was observed between the baseline and 10-min post-ipecac administration abdominal girth measurements. The time of emesis and volume of emesis were not significantly different in the water or carbonated beverage groups. We conclude that carbonated beverage administration does not alter the effectiveness of syrup of ipecac.

Abdomen↗
PubMed1981

Saliva-serum theophylline concentrations: substantial intrapatient and interpatient variation in predicting serum concentrations.

The relationships between serum and saliva concentrations were evaluated in 18 patients after single doses of three theophylline preparations. Simultaneous multiple saliva and serum samples were obtained after theophylline ingestion and were analyzed for theophylline content by the modified Schack and Waxler spectrophotometric method. Significant variability was observed in the data for those saliva/serum ratio sets obtained within 30 min of dosage. The mean correlation coefficient for saliva/serum sample sets obtained at and after 30 min was 0.86. Pearson product moment correlation coefficients determined for saliva/serum ratios at 2,4,6, and 8 hr ranged from 0.84 to 0.89, leaving 26% of the variance unexplained. Serum concentrations were calculated from a randomly selected saliva/serum ratio for each patient. Predicted serum concentrations were +/- 2 micrograms/ml of measured concentrations in only 143 of the 196 determinations (73%). Therefore, the use of saliva concentrations to predict serum values has substantial error in specific patients and may lead to incorrect dosage adjustments.

Adult↗
PubMed1978

Correlation of predicted versus measured creatinine clearance values in burn patients.

Four methods for predicting creatinine clearance (Ccr) from serum creatinine concentration (Scr) were evaluated in 19 male burn patients with burn wound sepsis. Measured Ccr values were calculated from 24-hour urinary catheter collections. Steady state Scr values were obtained during the same collection interval. Predicted Ccr values were derived from Scr using the methods of Cockcroft and Gault (Method II), Siersbaek-Nielsen, Kampmann and others (Method III) and Jeliffe (Methods I and IV). Wide differences between measured and predicted values were observed but were statistically significant (p less than 0.05) for Method I only. The smallest mean difference (+/-0.02 ml/min/1.73 m2) occurred with Method II measured-predicted data pairs. Method III predicted Ccr values which correlated best with measured values (r=0.770) and showed the least variability (+/-7.6 ml/min/1.73 m2). All methods appeared to overestimate when measured Ccr was less than 60 ml/min/1.73 m2. Use of estimated lean body weights did not improve correlations between predicted and measured Ccr values. While Methods II and III may provide useful initial approximations of Ccr in burn patients, reliance upon predicted Ccr values for dosage modification in burn patients may result in an insufficient reduction in dosage. Whenever possible, dosage regimens for drugs with narrow therapeutic margins should be developed or adjusted using pharmacokinetic values determined in the individual patient.

Adult↗
PubMedDate not supplied

Determination of theophylline bioavailability using saliva theophylline concentrations.

Substantial error occurs when individual saliva theophylline concentrations are used to predict serum theophylline concentrations. However, the use of saliva theophylline concentrations to determine product bioavailability has never been evaluated. Subjects in this study were 18 stable patients (20-51 yr) with a history of chronic obstructive pulmonary disease. Three preparations--a capsule (Elixophyllin 400 mg), elixir (Elixophyllin 373 mg), and tablet (Theolair 375 mg)--were administered in a randomized crossover design. Serum and saliva samples were obtained pre-dose and 0.25, 0.5, 1, 2, 4, 6, and 8 hours after theophylline administration. The saliva AUC0-infinity and serum AUC0-infinity were highly associated for the elixir (r = 0.84) tablet (r = 0.89), and capsule (r = 0.89). The bioavailability of the tablet and capsule calculated from elixir saliva and elixir serum AUC0-infinity were not significantly different (p = 0.2). The bioavailability of the tablet calculated from saliva and serum was 93% and 102%, respectively. The bioavailability of the capsule calculated from saliva and serum was 113% and 102% respectively. Our data suggests that theophylline bioavailability can be reliably estimated from saliva theophylline concentrations. However, study designs that include larger sample sizes and more frequent sampling may be necessary when determining bioavailability from saliva.

Adult↗
PubMedDate not supplied

Stability and delivery of vancomycin hydrochloride when admixed in a total parenteral nutrition solution.

Vancomycin hydrochloride, 400 mg/liter was mixed in six standard pediatric parenteral nutrition solutions with and without heparin added. The solutions were stored over a period of 8 days (192 hr) under refrigeration and at room temperature. Aliquots from all six solutions were assayed in duplicate for vancomycin at time 0, 24, 96, and 192 hr. All samples were run through an Ivex 0.22-micron filter, observed for physical incompatibilities, and frozen at -70 degrees C until assay. Our results indicate that vancomycin was stable and was delivered with loss in concentration of less than 5% with and without storage under refrigeration. This study suggests an alternative method for delivering vancomycin when treating a catheter-related infection. If vancomycin is delivered in this fashion, less manipulations of the line would be required. In addition, there may be a theoretical advantage of constantly bathing the catheter with vancomycin when the catheter is suspected of harboring the infecting organism.

Drug Stability↗
PubMedDate not supplied

Nitroglycerin adsorption to a combination polyvinyl chloride, polyethylene intravenous administration set.

Loss of nitroglycerin (NTG) from intravenous solutions to intravenous bags and administration sets has been well documented. This study was designed to examine a commercially available low adsorption administration set that was compatible with a volumetric infusion pump. A solution of NTG 100 micrograms/ml in dextrose 5% in glass bottles was used. Six study administration sets were tested. The infusion sets were connected to the NTG-containing glass bottles, filled as rapidly as possible, placed in the infusion pump, and set at the appropriate rate. Effluent was collected for NTG assay initially, and at 20 and 40 minutes, and 1, 1.5, 2, 3, 6, and 24 hours. The effects of flow rate were studied at 0.2 and 1.0 ml/min. The tubing performed similarly to other polyvinyl chloride (PVC)-containing sets at 0.2 ml/min and similar to non-PVC sets at 1.0 ml/min. The effect of an initial flush with 20-100 ml of 100 micrograms/ml NTG was also examined. An initial flush of 20 ml of 100 micrograms/ml NTG solution was found to enhance delivery of NTG immediately. NTG aliquots were stored frozen in glass vials prior to assay by high performance liquid chromatography.

Adsorption↗
PubMedDate not supplied

Practice models used by pharmacists in rural Minnesota to obtain Medicare reimbursement.

OBJECTIVES: (1) Define "incident-to" rules for Medicare reimbursement; (2) Describe how pharmacists can meet incident-to rules; (3) Provide examples of models of practice in rural areas that could be useful for meeting incident-to rules; and (4) Develop a strategy for creating a pharmacy practice model that could meet Medicare reimbursement rules in rural areas. DESIGN AND PARTICIPANTS: A survey of participants from the Pharmacy Rural Education, Practice and Policy Institute and the College of Pharmacy, University of Minnesota. SETTING: Community, hospital, and clinic practice sites in rural Minnesota. RESULTS: Four distinct models of practice have evolved that meet the incident-to rules of Medicare for reimbursement. Travel, proximity to physicians, and employment are the major determinants of the models described. CONCLUSION: Pharmacists in rural areas have demonstrated the ability to satisfy the incident-to rules for Medicare reimbursement. Collaborative agreements with physicians must include specific employment, practice, and supervisory relationships in order to satisfy these rules.

Centers for Medicare and Medicaid Services, U.S.↗
PubMedDate not supplied

The effect of heparin on three whole blood activated clotting tests and thrombin time.

Whole blood activated clotting time (ACT) can be determined by many different methods that use a variety of clotting cascade activators and end-points. This study compared the results of three whole blood ACT instruments at equivalent concentrations of heparin. Whole blood (9.8 ml) from 10 healthy adult volunteers without coagulation abnormalities was added to 0.2 ml of heparin solution producing heparin concentrations of 0, 0.1, 0.2, 0.4, 0.6, 0.8, and 1.0 U/ml. Coagulation status was determined in duplicate with the Hemochron 400 System (HC), the HemoTec Automated Coagulation Timer (HT), and the TriMed ACTivator (TM). Thrombin times or dilutions (TT) were also determined for each sample. Baseline values did not differ (p greater than 0.05); however, the HT and TM ACT values were significantly longer (p less than 0.05) than the HC ACT values at predicted heparin concentrations greater than 0.2 U/ml. Results from the HT and TM instruments were not significantly different. The HT and TM instruments both provided a greater ACT range over the heparin concentrations tested. Of the tests studied to monitor heparin therapy, mean scaled TTs showed the best correlation with predicted heparin concentrations.

Adult↗
PubMedDate not supplied

Pharmacokinetics of fluconazole in immune-compromised children with leukemia or other hematologic diseases.

STUDY OBJECTIVE: To describe the pharmacokinetics of fluconazole in immune-compromised children with leukemia or other hematologic disease. DESIGN: Prospective. SETTING: Children's Health Care-Minneapolis hematology/oncology inpatient ward and outpatient clinic. PATIENTS: Ten immune-compromised children (mean +/- SD age 7.4 +/- 4.0 yrs, weight 31.6 +/- 25.9 kg) with leukemia or other hematologic disease. INTERVENTIONS: Serum was sampled before and after a single 6-mg/kg intravenous dose and after seven oral 3-mg/kg doses of fluconazole. MEASUREMENTS AND MAIN RESULTS: Mean (SD) pharmacokinetics were distribution half-life 1.67 (1.25) hours, elimination half-life 15.62 (3.21) hours, total body clearance 0.63 (0.19) ml/min/kg, volume of distribution for the central compartment 0.56 (0.10) L/kg, volume of distribution at steady state 0.77 (0.12) L/kg, absorption half-life 0.41 (0.26) hour, and oral bioavailability 0.92 (0.09). Volume of distribution for the central compartment was highly correlated with body surface area (r2 = 0.891) and weight (r2 = 0.949). Volume of distribution at steady state correlated with body surface area (r2 = 0.986), and total body clearance correlated with body surface area (r2 = 0.867). CONCLUSIONS: Fluconazole elimination was well described using a two-compartment model. Oral absorption was rapid and nearly complete. Children have a larger volume of distribution for the central compartment and faster elimination rate than adults. Body surface area and weight are important factors in determining pharmacokinetics in these patients.

Absorption↗
PubMedDate not supplied

Activated clotting time tests with heparinase in the management of pediatric patients on cardiopulmonary bypass.

Routine ACT tests cannot distinguish between prolonged blood clotting due to heparin effect or acquired abnormalities of the coagulation system after a loading dose of heparin. The purpose of this study was to examine an ACT test that inactivates heparin with Heparinase allowing for ACT assessment with and without heparin effect (HR-ACT with/without Heparinase, HemoTec, Inc.). The HR-ACT values were compared with the standard OR procedure that employed the Hemochron ACT. Twenty pediatric patients undergoing cardiopulmonary bypass for repair of cardiac defects were examined. All comparative ACT values were obtained from the same blood sample. Five sampling times were examined: 1) A baseline ACT was obtained before heparin had been administered; 2) A pre bypass ACT after a single heparin dose; 3) On bypass; 4) A post protamine ACT at the conclusion of surgery; and 5) In the Intensive Care Unit (PICU), 1 hour post protamine. The HemoTec HR-ACT with Heparinase and HR-ACT tests differentiated clotting time results that reflected coagulation status without the heparin effect. It identified those patients on bypass who were less than 5 kg, with prolonged ACTs that were due in part to hemodilution despite efforts at hemoconcentration.

Adolescent↗
PubMedDate not supplied

Predictive performance of three methods of activated clotting time measurement in neonatal ECMO patients.

Previously reported activated clotting time (ACT) data in adults demonstrated higher values with the HemoTec LRACT (HT) and TriMed ACTivator (TM) techniques than with the Hemochron System P214/215 (HC) technique throughout a range of heparin concentrations. This study sought to determine if a difference exists in ACT values of neonatal patients receiving ECMO. ACTs were performed in nine neonatal ECMO patients using the HC, HT, and TM techniques. Techniques were compared for positive or negative direction of any prediction difference (bias), and the typical value of a difference (precision). Simultaneous, duplicate, morning, and afternoon ACT comparisons were obtained using all three techniques. Forty-six comparisons of HC values in the 180-240 sec range were analyzed. All techniques produced results different from the same sample. The HT and TM techniques were upwardly biased by 51 and 148 sec, respectively, when evaluated against HC. HT was negatively biased by 123 sec when evaluated against TM. Because ACT values vary among techniques, ACT target ranges should be technique specific. Future references to ACT data should identify the equipment and procedures employed.

Bias↗