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Biomedical subjects

E Doyle

Publications and source records attributed to E Doyle.

At least 19 recordsLinked to original sources

A comparison of the respiratory effects of high concentrations of halothane and sevoflurane.

We studied the respiratory effects of the administration of either 5% halothane or 8% sevoflurane in 70% nitrous oxide (N2O) for 5 min in 21 boys aged 1-5 years. A similar degree of ventilatory depression was noted with both agents. Minute volume fell by approximately 50% as a result of a reduction in tidal volume despite an increase in respiratory rate.

Anesthesia, Epidural↗

In vitro activity of gemifloxacin (SB-265805, LB20304a) against Legionella pneumophila and its pharmacokinetics in guinea pigs with L. pneumophila pneumonia.

The activity of gemifloxacin against intracellular Legionella pneumophila and for the treatment of guinea pigs with L. pneumophila pneumonia was studied. Gemifloxacin, azithromycin, and levofloxacin (1 microg/ml) reduced bacterial counts of two L. pneumophila strains grown in guinea pig alveolar macrophages by 2 to 3 log(10) units. Gemifloxacin and levofloxacin had roughly equivalent intracellular activities. In contrast, erythromycin had static activity only. Therapy studies of gemifloxacin, azithromycin, and levofloxacin were performed in guinea pigs with L. pneumophila pneumonia. When gemifloxacin (10 mg/kg) was given by the intraperitoneal (i.p.) route to infected guinea pigs, mean peak levels in plasma were 1.3 microg/ml at 0.5 h and 1.2 microg/ml at 1 h postinjection. The terminal half-life phase of elimination from plasma was 1.3 h, and the area under the concentration-time curve from 0 to 24 h (AUC(0--24)) was 2.1 microg. h/ml. For the same drug dose, mean levels in lungs were 3.4 microg/g at both 0.5 and 1 h, with a half-life of 1.5 h and an AUC(0--24) of 6.0 microg. h/ml. All 15 L. pneumophila-infected guinea pigs treated with gemifloxacin (10 mg/kg/dose given i.p. once daily) for 2 days survived for 9 days after antimicrobial therapy, as did 13 of 14 guinea pigs treated with the same dose of gemifloxacin given for 5 days. All 12 azithromycin-treated animals (15 mg/kg/dose given i.p. once daily for 2 days) survived, as did 11 of 12 animals treated with levofloxacin (10 mg/kg/dose given i.p. once daily for 5 days). None of 12 animals treated with saline survived. Gemifloxacin is effective against L. pneumophila in infected macrophages and in a guinea pig model of Legionnaires' disease, even with an abbreviated course of therapy. These data support studies of the clinical effectiveness of gemifloxacin for the treatment of Legionnaires' disease.

Animals↗

Rapid determination of gemifloxacin in human plasma by high-performance liquid chromatography-tandem mass spectrometry.

A method was developed for the determination of gemifloxacin (I) in human plasma using high-performance liquid chromatography-tandem mass spectrometry. Prior to analysis, the protein in plasma samples was precipitated with acetonitrile containing [13C2H3] gemifloxacin (II) to act as an internal standard. The supernatant was injected onto a PLRP-S column without any further clean-up. The mass spectrometer was operated in positive ion mode, employing a heat assisted nebulisation. electrospray interface. Ions were detected in multiple reaction monitoring (MRM) mode. The assay requires 50 microl of plasma and is precise and accurate within the range 10-5,000 ng/ml. The average within-run and between-run coefficients of variation were <11% at 10 ng/ml and greater concentrations. The average accuracy of validation standards was generally within +/-7% of the nominal concentration. There was no evidence of instability of I in human plasma following three complete freeze-thaw cycles and samples can safely be stored for at least 6 months at -20 degrees C. The method proved very robust and was successfully applied to the analysis of clinical samples from patients dosed with gemifloxacin.

Anti-Infective Agents↗

Pretreatment with ranitidine does not reduce the bioavailability of orally administered topotecan.

PURPOSE: The purpose of this randomized, two-period crossover study was to determine the pharmacokinetics of orally administered topotecan in the presence and absence of oral ranitidine. METHODS: Patients with solid malignant tumors refractory to standard treatment were given topotecan orally on a daily times five schedule repeated every 21 days. Topotecan was given initially at 2.3 mg/m2 per day; dose adjustments were permitted after the first dose of course 2 if necessary. Blood samples for pharmacokinetic assessments were drawn at protocol-specified times for up to 10 h following oral administration of topotecan on day 1 of courses 1 and 2. Patients were randomly assigned to receive a total of nine doses of ranitidine: 150 mg twice daily for 4 days before day 1 of one of the first two courses and 150 mg given 2 h before the first topotecan dose. Plasma samples were assayed for concentrations of active topotecan lactone (TPT-L) and total topotecan (TPT-T, lactone plus open-ring carboxylate form) using high-performance liquid chromatography with fluorescence detection. After completion of courses 1 and 2, patients could continue on therapy for days 1-5 of every 21 days if not withdrawn due to unacceptable toxicity, disease progression, protocol violation, or by request. Patients continued on treatment for a maximum of six courses. RESULTS: No pharmacokinetic parameter for either TPT-L or TPT-T differed significantly during administration of topotecan with ranitidine compared with topotecan alone (n = 13). Geometric mean ratios (95% confidence intervals, CIs) of areas under the curve in the presence and absence of ranitidine were 0.94 (0.80, 1.10) for TPT-L and 0.97 (0.80, 1.16) for TPT-T. Corresponding ratios (CIs) of peak plasma concentrations in the presence and absence of ranitidine were 1.06 (0.78, 1.44) for TPT-L and 1.07 (0.84, 1.38) for TPT-T. The median difference in time to peak plasma concentration was 0.0 h for TPT-L and -0.5 h for TPT-T (i.e. slightly faster in the presence of ranitidine). CONCLUSIONS: Administration of ranitidine prior to oral topotecan resulted in a similar extent of absorption. A slightly faster rate of absorption of topotecan was also observed, which is unlikely to be of clinical significance. Dosage adjustments of orally administered topotecan should not be necessary in patients who are pretreated with ranitidine, an H2 antagonist, or another agent that comparably raises gastric pH.

Administration, Oral↗

Phase I pharmacologic study of oral topotecan and intravenous cisplatin: sequence-dependent hematologic side effects.

PURPOSE: In in vitro studies, synergism and sequence-dependent effects were reported for the combination of topotecan and cisplatin. Recently, an oral formulation of topotecan became available. This phase I study was performed to assess the feasibility of the combination of oral topotecan and cisplatin, the pharmacokinetic interaction, and sequence-dependent effects. PATIENTS AND METHODS: Topotecan was administered orally (PO) daily for 5 days in escalating doses and cisplatin was given intravenously (IV) at a fixed dose of 75 mg/m(2) either before topotecan administration on day 1 (sequence CT) or after topotecan administration on day 5 (sequence TC) once every 3 weeks. Patients were treated in a randomized cross-over design. RESULTS: Forty-nine patients were entered onto the study; one patient was not eligible. Sequence CT induced significantly more severe myelosuppression than did sequence TC, and the maximum-tolerated dosage of topotecan in sequence CT was 1.25 mg/m(2)/d x 5. In sequence TC, the maximum-tolerated dosage of topotecan was 2.0 mg/m(2)/d x 5. Dose-limiting toxicity consisted of myelosuppression and diarrhea. Pharmacokinetics of topotecan and cisplatin were linear over the dose range studied; no sequence-dependent effects were observed. In addition, topotecan did not influence the protein binding of cisplatin or the platinum-DNA adduct formation in peripheral leukocytes in either sequence. CONCLUSION: The recommended dosages for phase II studies involving patients like the patients in our study are topotecan 1.25 mg/m(2)/d PO x 5 preceded by cisplatin 75 mg/m(2) IV day 1 once every 3 weeks, and topotecan 2.0 mg/m(2)/d PO followed by cisplatin 75 mg/m(2) IV day 5. No pharmacokinetic interaction could be discerned in our study. The antitumor efficacy of both schedules should be evaluated in a randomized phase II study.

Adult↗

Quantification of topotecan and its metabolite N-desmethyltopotecan in human plasma, urine and faeces by high-performance liquid chromatographic methods.

Sensitive high-performance liquid chromatographic (HPLC) methods have been developed and validated for the simultaneous determination of the antitumor drug topotecan and its metabolite N-desmethyltopotecan in human plasma, urine and faeces. Both compounds are reversibly hydrolysed to their hydroxycarboxylate forms at physiologic pH. Separate HPLC systems have been developed for the determination of lactone and total (lactone plus hydroxycarboxylate forms) concentrations in plasma. The instability of the analytes in plasma requires immediate protein precipitation with ice-cold methanol. The lactone forms of the analytes were stable in the methanol extracts for at least 15 months when stored at -70 degrees C. For the determination of the total levels, the plasma extracts were acidified with 25 mM phosphoric acid to convert the compounds into their lactone forms quantitatively. The sample pretreatment procedure for urine included dilution in methanol while the faecal samples were homogenized in distilled water and then extracted twice with an acetonitrile-ammonium acetate mixture. Separation was achieved on reversed-phase columns (Zorbax SB-C18) and detection was performed fluorimetrically at 380/527 nm. Within-run and between-run precisions were less than 10% and average accuracies were between 90 and 110%. The methods were used in a mass balance study in patients with malignant solid tumors to determine the disposition and routes of elimination of topotecan and N-desmethyltopotecan.

Antineoplastic Agents↗

Oral topotecan: bioavailablity and effect of food co-administration.

The aims of the study were twofold: (1) to evaluate the effect of food on the relative oral bioavailability of topotecan gelatin capsules in patients with solid tumours, and (2) to determine the absolute bioavailability of oral topotecan with reference to the intravenous (i.v.) formulation. The study had a randomized two-period cross-over design. On day 1 of the first treatment course patients were administered 2.3 mg m(-2) day(-1) of oral topotecan with or without a high-fat breakfast. They crossed over to receive the alternate regimen on day 2. In the second course (3 weeks later) fasted patients received topotecan orally (2.3 mg m(-2) day(-1)) or i.v. (1.5 mg m(-3) day). They crossed over to receive the alternate regimen on day 2. On days 3-5 of both treatment courses patients received oral topotecan. Plasma pharmacokinetics were performed on days 1 and 2 of the first and second course using a high-performance liquid chromatographic assay. Eighteen patients were enrolled in the study. The ratio of the area under the curve to infinity during fasted and high-fat treatment was 0.93+/-0.23 (90% confidence interval (CI) 0.83-1.03). Maximal plasma concentrations of topotecan were similar after ingestion of the capsules with (10.6+/-4.4 ng ml(-1)) or without food (9.2+/-4.1 ng ml(-1)) (P = 0.130). The time needed to reach maximal plasma levels was significantly prolonged after food intake (median 3.1 h, range 2.8-6.1) compared to fasted conditions (2.0 h, range 1.1-8.1) (P = 0.013). The absolute bioavailability of topotecan averaged 42+/-13% (90% CI 37-47%). The apparent terminal half-life was significantly longer after administration of oral topotecan (3.9+/-1.0 h) than after i.v. administration (2.7+/-0.4 h) (P < 0.001). Topotecan demonstrates suitable bioavailability for oral treatment. Co-administration of the topotecan gelatin capsules with a high-fat breakfast leads to a small decrease in absorption rate but does not affect the extent of absorption.

Administration, Oral↗

The intravascular migration of an epidural catheter.

The intravascular migration of an endhole epidural catheter in a child is described. We suggest measures to reduce the risk of inadvertent intravenous administration of local anaesthetic and means of reducing the effects of this with particular relevance to paediatric practice.

Anesthesia, Epidural↗

Comparison of morphine sulphate and codeine phosphate in children undergoing adenotonsillectomy.

We undertook a double-blind study to evaluate equianalgesic doses of intramuscular morphine sulphate (0.15 mg.kg-1) and codeine phosphate (1.5 mg.kg-1) in 40 healthy children undergoing adenotonsillectomy. There were no significant differences in pain scores, analgesic requirements or sedation scores between the two groups over the following 24 h. More children vomited in the morphine group (60%) than the codeine group (30%) between one and six h after the procedure (P < 0.05). Codeine phosphate is associated with less postoperative vomiting than morphine sulphate while providing comparable postoperative analgesia for adenotonsillectomy.

Adenoidectomy↗

Search for the PARK3 founder haplotype in a large cohort of patients with Parkinson's disease from northern Germany.

A founder haplotype on chromosome 2p for autosomal dominant Parkinson's disease (PD) has been postulated for two families of Northern European descent, and a new mutation in the alpha-synuclein gene (Ala30Pro) has been found in a German PD family. We evaluated 85 German PD patients and 85 ethnically matched controls for shared markers on chromosome 2p and for the new alpha-synuclein mutation. We found no evidence for linkage disequilibrium, suggesting that the putative founder mutation on chromosome 2p is not a common cause of PD in the local population. Furthermore, no patient carried the Ala30Pro change, supporting earlier findings that mutations in the alpha-synuclein gene are extremely rare.

Aged↗

Phase I and pharmacologic study of the combination of paclitaxel, cisplatin, and topotecan administered intravenously every 21 days as first-line therapy in patients with advanced ovarian cancer.

PURPOSE: To evaluate the feasibility of administering topotecan in combination with paclitaxel and cisplatin without and with granulocyte colony-stimulating factor (G-CSF) support as first-line chemotherapy in women with incompletely resected stage III and stage IV ovarian carcinoma. PATIENTS AND METHODS: Starting doses were paclitaxel 110 mg/m2 administered over 24 hours (day 1), followed by cisplatin 50 mg/m2 over 3 hours (day 2) and topotecan 0.3 mg/m2/d over 30 minutes for 5 consecutive days (days 2 to 6). Treatment was repeated every 3 weeks. After encountering dose-limiting toxicities (DLTs) without G-CSF support, the maximum-tolerated dose was defined as 5 microg/kg of G-CSF subcutaneously starting on day 6. RESULTS: Twenty-one patients received a total of 116 courses at four different dose levels. The DLT was neutropenia. At the first dose level, all six patients experienced grade 4 myelosuppression. G-CSF support permitted further dose escalation of cisplatin and topotecan. Nonhematologic toxicities, primarily fatigue, nausea/vomiting, and neurosensory neuropathy, were observed but were generally mild. Of 15 patients assessable for response, nine had a complete response, four achieved a partial response, and two had stable disease. CONCLUSION: Neutropenia was the DLT of this combination of paclitaxel, cisplatin, and topotecan. The recommended phase II dose is paclitaxel 110 mg/m2 (day 1), followed by cisplatin 75 mg/m2 (day 2) and topotecan 0.3 mg/m2/d (days 2 to 6) with G-CSF support repeated every 3 weeks.

Adult↗

The effect of ketamine on 0.25% and 0.125% bupivacaine for caudal epidural blockade in children.

Forty boys aged from one to five years undergoing orchidopexy were randomly allocated to receive one of two solutions for caudal epidural injection. Group A received 1 ml.kg-1 of 0.125% bupivacaine with ketamine 0.5 mg.kg-1 and Group B received 1 ml.kg-1 of bupivacaine 0.25% with ketamine 0.5 mg.kg-1. Postoperative pain was assessed by means of a modified Objective Pain Score and analgesia was administered if this score exceeded four. The median duration of caudal analgesia was 8 h in Group A compared with 9.5 h in Group B (P<0.05). The time taken to recover the ability to walk was a median of two h in Group A and three h in Group B (P<0.05). There were no differences between the groups in the incidence of urinary retention or postoperative sedation.

Acetaminophen↗

Modifying infant stress responses to major surgery: spinal vs extradural vs opioid analgesia.

Twenty-six infants due to undergo major abdominal or thoracic surgery under general anaesthesia were randomized to receive additional analgesia with group A) spinal/epidural analgesia; B) epidural analgesia or C) opioid analgesia with fentanyl. We wished to determine if spinal analgesia followed by epidural analgesia might result in more complete control of cardiovascular or stress responses than the other two treatment groups. Heart rate and blood pressure were recorded at five min intervals throughout surgery. Blood samples were taken for measurement of catecholamines and whole blood sugar on induction, 45 min after skin incision and at the end of surgery. Heart rate rose significantly at the start of surgery in groups B and C but not group A. Systolic blood pressures were higher in group C compared to A and B. The rise in plasma glucose concentrations was significantly different between the groups in the order C > B > A (P < 0.05). A similar trend was seen in the plasma adrenaline and noradrenaline concentrations but this failed to achieve significance due to the limited sample size.

Abdomen↗

Pre-emptive effect of multimodal analgesia in thoracic surgery.

Thirty subjects undergoing posterolateral thoracotomy were allocated randomly to receive one of two analgesic regimens: group Pre received i.v. morphine, i.m. diclofenac and intercostal nerve blocks from T2 to T11, 20 min before operation and placebo injections after operation. Group Post received placebo injections before operation, and i.v. morphine, i.m. diclofenac and intercostal nerve blocks from T2 to T11 at the end of surgery, before discontinuation of anaesthesia. Visual analogue pain scores, extent and duration of intercostal nerve block, analgesic consumption and complications were assessed during the postoperative period by a single blinded observer. Subjects were followed-up for a minimum of 12 months to determine the incidence of post-thoracotomy pain syndrome. During the first 48 h after operation there were lower pain scores in group Pre when taking a vital capacity breath but there were no significant differences between the groups in any other measure. The effects of pre-emptive analgesia given before surgery appeared to be relatively modest in terms of analgesia, analgesic consumption and long-term outcome and were of limited clinical significance.

Adult↗