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Biomedical subjects

P F Souney

Publications and source records attributed to P F Souney.

At least 19 recordsLinked to original sources
PubMed1996

Effects of ofloxacin administration on the reliability of urine glucose testing.

OBJECTIVE: To study the effects of ofloxacin on the reliability of urine glucose testing. DESIGN: Open-label, nonrandomized. SETTING: A university-affiliated tertiary care hospital, ambulatory clinic. PARTICIPANTS: Ten healthy volunteers (8 men and 2 women) aged 22-39 years. MAIN OUTCOME MEASURES: Phase I (in vitro) involved the addition of selected amounts of ofloxacin to a set of standard 50-mL urine samples prepared to simulate glycosuria. Phase II (in vivo) involved the oral administration of ofloxacin 400 mg to 10 subjects. Urine was collected: (1) immediately predose, (2) pooled 0-4 hours postdose, and (3) pooled 4-8 hours postdose. Known glucose concentrations were then added to these samples. Clinitest and Diastix tests were performed on all samples. The accuracy of these tests in determining glucose concentrations was compared among urine samples taken before and after ofloxacin dosing. RESULTS: None of the ofloxacin concentrations in phase I (0, 25, 50, 100, 200, 400, and 800 micrograms/mL) influenced these testing methods at the urine glucose concentrations of 0.0%, 0.5%, 1%, and 2%. Likewise, the accuracy of these two tests was unaffected by ofloxacin administration in phase II. CONCLUSIONS: In single-dose administration, ofloxacin does not interfere with Clinitest or Diastix for determining urine glucose concentrations.

Adult↗
PubMed1995

A fluorimetric liquid chromatographic method for the determination of propranolol in human serum/plasma.

A simple, rapid, and sensitive fluorimetric-high-performance liquid chromatographic method for the determination of propranolol in human serum/plasma has been developed, without the need for solvent extraction. The procedure required 200 microliters of serum/plasma, and the addition of 1 ml of acetonitrile for protein precipitation followed by vortexing and centrifugation at 10 000 g. The clear supernatant was evaporated to dryness under a stream of nitrogen at 50-60 degrees C, the residue was reconstituted in 100 microliters of methanol, and a 90 microliters portion was injected onto the high-performance liquid chromatograph for propranolol quantitation. Chromatography was accomplished using a Hypersil cyano column, a mobile phase of acetonitrile-aqueous acetic acid (1%) containing 0.2% triethylamine (35:65, v/v) (pH 3.6), a flow rate of 1.5 ml min-1, a fluorescence detector set at an excitation wavelength of 230 nm and an emission wavelength of 340 nm, and using pronethalol as the internal standard. Retention times for pronethalol and propranolol were 7.5 min and 9.5 min, respectively. Standard curves were linear in the range 5-200 ng ml-1. Relative standard deviations for both inter-day and intra-day precision analysis were less than 7% for serum. No interference was observed from endogenous serum/plasma components. Specificity was shown for some, but not all, commonly coadministered drugs tested. The advantages of this method include good precision, low sample volume, good reproducibility and recovery, and high sensitivity.

Adrenergic beta-Antagonists↗
PubMed1993

Crossover comparison of drug information online database vendors: Dialog and MEDLARS.

OBJECTIVE: To compare Dialog EMBASE with the National Library of Medicine's (NLM's) MEDLARS MEDLINE, TOXLINE, and TOXLIT to evaluate differences among the databases and vendors in a method consistent with routine drug information practice. DESIGN: Crossover comparison. METHODS: NLM MEDLARS databases MEDLINE, TOXLINE, and TOXLIT were searched directly. EMBASE was searched via Dialog Information Services. MEDLINE was searched back to 1980; TOXLINE and TOXLIT were searched back to 1981, reflecting the different database structures. EMBASE was searched back to 1980. To control bias, searches were randomized; identical strategies were used during the same session and were performed by the same trained searcher. RESULTS: Twenty-six drug information requests were compared. The MEDLARS and Dialog databases were generally similar, with no significant differences in the number of potentially relevant references, English references, clinically relevant references, available abstracts, unique citations, time online, and number of questions answered. EMBASE searches were more costly (p = 0.0005). TOXLIT was costlier than TOXLINE and MEDLINE (p = 0.0018). CONCLUSIONS: NLM MEDLARS databases were comparable to Dialog EMBASE. Although MEDLARS provided more total and English-language citations, the differences were small and did not influence the proportion of questions answered. The greatest difference between the vendors was the significantly lower cost of searching on MEDLARS. Although this difference may be partially offset by the significantly shorter search times on EMBASE, the mean 1.9 minutes saved would not recoup the mean $7.89 difference in cost. MEDLARS databases are less expensive for routine drug information requests.

Costs and Cost Analysis↗
PubMed1993

Stability of cyclosporine with magnesium sulfate in 5% dextrose injection.

The compatibility and stability of cyclosporine with magnesium sulfate in 5% dextrose injection was studied. Cyclosporine solution 50 mg/mL was added to each of three glass bottles containing magnesium sulfate injection and 5% dextrose injection; final theoretical concentrations of cyclosporine and magnesium sulfate were 2.0 mg/mL and 30 mg/mL, respectively. The samples were stored under fluorescent lighting at controlled room temperature (24 +/- 2.4 degrees C). At 6, 12, 24, and 36 hours each solution was visually inspected under normal lighting against a white and black background for color change, haze, or precipitation. Samples were assayed in duplicate for cyclosporine concentration by using a stability-indicating high-performance liquid chromatographic method. Turbidity occurred immediately after mixing but resolved in approximately 30 seconds. No other changes in clarity or color were noted. The admixtures retained > 90% of initial cyclosporine concentration for six hours, and there were no significant differences in mean cyclosporine concentrations among the individual samples. Cyclosporine 2.0 mg/mL added to magnesium sulfate 30 mg/mL in 5% dextrose injection was stable for six hours when stored in glass bottles at 24 degrees C under fluorescent lighting.

Cyclosporine↗
PubMed1992

The effect of vasoactive intestinal polypeptide on the lower esophageal sphincter in achalasia.

Vasoactive intestinal polypeptide (VIP) is one of the main neurotransmitters implicated in the relaxation of the lower esophageal sphincter (LES). The effect of exogenous VIP on LES motor activity was determined by esophageal manometry. LES pressure (LESP) and LES relaxation were compared in four healthy volunteers and in six patients with achalasia. The effects of intravenous doses of 1.5, 3, and 5 pmol.kg-1.min-1 of VIP were compared with placebo. Neither placebo nor 3 and 5 pmol.kg-1.min-1 of VIP produced any effect on esophageal motility in healthy volunteers. In achalasia the three doses of VIP caused a dose-dependent decrease in LESP with a significant improvement in LES relaxation. A dose of 5 pmol.kg-1.min-1 produced a maximal decrease of 51% in LESP. A beta-adrenergic agonist, isoproterenol, caused a decrease in LESP both in healthy volunteers and in patients with achalasia without improving LES relaxation. In summary, intravenous VIP improved LES relaxation and caused a decrease in LESP in patients with achalasia without affecting LESP in healthy volunteers, indicating that the LES muscle in achalasia is supersensitive to VIP. The current study suggests that a selective damage in the noncholinergic nonadrenergic innervation of the esophagus is in part responsible for the motor alteration seen in these patients. The findings and the inability of isoproterenol to improve LES relaxation despite decreasing LESP support a role in VIP as a indicator of LES relaxation.

Adolescent↗
PubMed1991

Transcutaneous electrical nerve stimulation decreases lower esophageal sphincter pressure in patients with achalasia.

Vasoactive intestinal peptide (VIP) is believed to be an inhibitory neurotransmitter responsible for lower esophageal sphincter (LES) relaxation. In patients with achalasia the concentration of VIP and the number of VIP-containing nerve fibers are reduced or absent. It has been suggested that the response to low-frequency transcutaneous electrical nerve stimulation (TENS) may be mediated by a nonadrenergic noncholinergic pathway in which the release of VIP is responsible for the smooth muscle relaxation. The present study was designed to evaluate the effect of TENS on LES pressure and on VIP plasma concentrations in six patients with achalasia (five female, one male). TENS was performed daily during one week for 45-min sessions with a pocket stimulator that delivered low-frequency pulses (6.5 Hz), at 10 pulses/sec of 0.1-msec duration at intensities of 10-20 mA until rhythmic flexion of the fingers was obtained without producing pain. LES pressure and VIP levels were obtained before TENS, after the first 45-min session, and after a week of daily stimulation. After 45-min, TENS produced a significant reduction (P less than 0.01) in LES resting pressure from the mean value 56 +/- 6.4 mm Hg to 42.3 +/- 6.4 mm Hg; with LES relaxation improvement from 50.6 +/- 3% to 63.1 +/- 3.2% (P less than 0.01). After one week of daily TENS, an additional reduction in LES resting pressure (40.3 +/- 4 mm Hg) was observed (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Therapeutic alternatives for subacute peripheral arterial occlusion. Comparison by outcome, length of stay, and hospital charges.

Thrombolytic therapy using streptokinase or urokinase has been shown to be a viable alternative to surgical thrombectomy in patients with subacute peripheral arterial occlusion. Urokinase is associated with higher success and lower complication rates than streptokinase, but the cost of urokinase is at least seven times higher. To address questions of utility and effectiveness in the treatment of subacute peripheral arterial occlusions, the authors designed a retrospective study of patients treated either by surgical thrombectomy (n = 70), thrombolysis with streptokinase (n = 19), or thrombolysis with urokinase (n = 22). Outcome of therapy, length of hospital stay, and total hospital charges in the three groups were examined. Treatment successes in the three groups, defined as complete clearing of the occluded segment with patency maintained for 60 days, were 76% for thrombectomy, 32% for streptokinase, and 64% for urokinase. Total duration of hospitalization was 21.1, 21.3, and 11.5 days (P less than .05), respectively. Mean charges for thrombolytic agents were $690 for streptokinase and $6429 for urokinase. Mean total hospital charges, however, were $25,978 for streptokinase, $22,203 for urokinase, and $25,336 for thrombectomy (P = NS). The higher cost of urokinase, then, accounted for the similar total charges, despite the shortened length of stay. These results suggest that urokinase is cost-effective compared to streptokinase for subacute peripheral arterial occlusion. Compared to thrombectomy, thrombolysis with urokinase has a marginally lower patency rate at 60 days, but a significantly shorter length of hospital stay.

Cost-Benefit Analysis↗
PubMed1991

High vasoactive intestinal polypeptide plasma levels in patients with Barrett's esophagus.

We have evaluated the correlation between vasoactive intestinal polypeptide (VIP) plasma concentration and severity of gastroesophageal reflux in patients with Barrett's esophagus and the possible differences in the VIP values of these patients compared with healthy volunteers. We also evaluated the relation between VIP plasma concentration and lower esophageal sphincter (LES) pressure in 24 patients with Barrett's esophagus. The mean VIP plasma concentration in 14 patients with severe gastroesophageal reflux was 25.6 +/- 0.75 pg/ml, significantly higher than the mean value observed in 10 patients with moderate reflux (18.9 +/- 0.67 pg/ml) (p less than 0.01). The mean LES resting pressure was significantly lower in the group of patients with severe gastroesophageal reflux than that observed in patients with moderate reflux (3 +/- 0.64 and 10.3 +/- 0.69 mm Hg, respectively; p less than 0.01). The mean VIP plasma concentration in 11 healthy volunteers (20.6 +/- 0.65 pg/ml) was significantly lower than the mean value observed in the subgroup of patients with severe gastroesophageal reflux (p less than 0.01). VIP values in patients with moderate reflux were not significantly different from those observed in our volunteers. There was a significant correlation between LES pressure and VIP plasma level (r = -0.9253; p less than 0.01). In conclusion, it is possible that the decreased LES resting pressure observed in patients with Barrett's esophagus and severe gastroesophageal reflux may be due to impairment of the VIPergic innervation, resulting in an increased local VIP release with possible overflow to peripheral plasma.

Adult↗
PubMed1991

The effect of transcutaneous nerve stimulation on sphincter of Oddi pressure in patients with biliary dyskinesia.

Vasoactive intestinal polypeptide (VIP) has been postulated as a neuropeptide with inhibitory neurotransmitter activity in nonadrenergic noncholinergic pathways. Transcutaneous electric nerve stimulation (TENS) relaxes the lower esophageal sphincter in patients with achalasia. Such response is accompanied by a 30% increase in VIP concentrations in the systemic circulation. Since the sphincter of Oddi (SO) receives a very dense VIP nerve supply, we evaluate the effect of TENS on SO motor activity and on VIP plasma concentrations in patients with biliary dyskinesia and in healthy volunteers. TENS was performed with a pocket stimulator for 45 min. SO pressure and VIP levels were obtained before and after 45 min of TENS. In patients with SO dyskinesia, TENS produced a significant decrease in SO pressure from 80.1 +/- 11.9 mm Hg to 58.3 +/- 9.7 mm Hg p less than 0.01); this was accompanied by a significant increase in VIP plasma levels from 21.1 +/- 0.5 pg/ml to 32.6 +/- 1.5 pg/ml (p less than 0.01). In healthy volunteers, TENS did not produce significant changes in SO pressure. However, a significant increase in VIP plasma values was observed (p less than 0.01). No significant changes in amplitude, duration and frequency of SO phasic contractions were observed in either of the two groups evaluated. We conclude that, in patients with SO dyskinesia, TENS decreases SO basal pressure, possibly by a direct action of the released VIP in the systemic circulation. In healthy volunteers, TENS increases VIP plasma values without significant effect on SO basal pressure. These findings suggest that the response to TENS may be mediated by VIP. It is also possible that the alterations seen in patients with biliary dyskinesia may be due to impairment of the VIP nerve supply at the level of the SO.

Adult↗
PubMed1990

Stability of famotidine in a 3-in-1 total nutrient admixture.

The stability of famotidine in a 3-in-1 total nutrient admixture stored at room temperature (24 degrees C) was evaluated over 24 hours. Famotidine injection was diluted to a theoretical concentration of 20 mg/L in a total nutrient admixture containing 5% amino acid injection, 25% dextrose injection, and 2.25% intravenous fat emulsion. Admixtures were prepared in 2-L ethylene-vinyl acetate bags using conventional techniques and stored at room temperature. At 0, 4, 8, 12, and 24 hours, the admixtures were visually inspected for color change, creaming, or phase separation, and samples were obtained for assay with a stability-indicating method of HPLC, using samples obtained at time zero as controls. Two-way analysis of variance was used for data evaluation. There was no evidence of color change, creaming, or phase separation before quantitative analysis was performed, nor was there significant change in observed famotidine concentration over 24 hours. Based upon our data, famotidine intravenous solution 20 mg/L in the solution tested is stable at room temperature for 24 hours.

Chromatography, High Pressure Liquid↗
PubMed1989

A critical review of continuous infusion H2 receptor therapy.

Recent studies suggest that continuous infusions of H2-receptor antagonists may be more effective than intermittent iv therapy to control gastric pH for the prevention of stress ulcers. Infusions of cimetidine, ranitidine, and famotidine have been shown either to have a beneficial clinical effect, to control gastric acid secretion, to maintain gastric pH greater than 4, or to have pharmacokinetic properties similar to intermittent doses. In addition, some evidence suggests that continuous infusions may permit the use of lower doses, leading to cost savings. However, as yet there have been no trials that directly compare continuous and intermittent regimens and show improved outcomes with a continuous regimen. Since candidates for parenteral administration of H2-receptor antagonists are most common in the ICU, several practical issues must be addressed. Patients who receive total parenteral nutrition (TPN) may be suitable candidates for continuous infusions of H2-blockers since these agents can be given in the same container as TPN solutions. These patients also usually have a parenteral access site and infusion pump dedicated to TPN administration. In other patients, drug incompatibilities, limited iv access lines, or a lack of infusion pumps may require frequent interruptions of the infusion in order to administer additional medications, which may lead to a loss of gastric pH control. In most patients, administration of an H2-blocker regimen which maintains consistent pH control after intermittent administration may be the most practical method by which to administer these agents.

Cimetidine↗
PubMed1989

Pharmacoeconomic aspects and formulary considerations related to histamine2-receptor antagonists.

Since the introduction of cimetidine in 1977, hospital expenditures for the histamine2-receptor antagonists have steadily increased, making them one of the most costly classes of therapeutic agents. As a result of cost considerations, we reviewed the available antiulcer agents in our hospital and evaluated the potential for therapeutic interchange within this group of agents. We found that by using famotidine as the principal agent in our hospital, drug cost savings of approximately $65,000 were realized. Additionally, avoiding the administration of approximately 13,000 parenteral doses with the selection of famotidine resulted in further reduction of drug administration costs. We conclude that the histamine2-receptor antagonists represent a cost-effective target for pharmacy cost-containment programs, without affecting patient therapeutic outcomes.

Formularies, Hospital as Topic↗
PubMed1988

Comparison of excretion of nicotinuric acid after ingestion of two controlled release nicotinic acid preparations in man.

We tested an inexpensive controlled-release nicotinic acid product (Bronson Pharmaceuticals, LaCanada, CA) and compared it with the standard, more expensive, controlled release product, Nicobid (Rorer Pharmaceuticals), by measuring the 24 hour urinary recovery of nicotinic and nicotinuric acids from ten subjects following 500 mg oral ingestion of each product. Nicotinuric acid is the major detoxification product of nicotinic acid and may serve as a simple quantitative index of hepatic biotransformation of nicotinic acid. Although both products demonstrated controlled release profiles, the rate of appearance of nicotinic and nicotinuric acid in the urine as well as the rate of in vitro drug dissolution of the Bronson product were more rapid compared with Nicobid. Moreover, the total amounts of nicotinic acid and nicotinuric acid recovered in the urine after 24 hours were greater for the Bronson product (P less than .05). Since sustained presentation of nicotinic acid to the liver may correlate with clinical antihyperlipidemic effects, our results suggest that the Bronson product may prove to be a clinically useful preparation.

Adult↗