The effect of different doses of cyclosporin A on the systemic exposure of orally administered paclitaxel

The objective of this study was to define the minimally effective dose of cyclosporin A (CsA) that would result in a maximal increase of the systemic exposure to oral paclitaxel. Six evaluable patients participated in this randomized cross-over study in which they received at two occasions two doses of 90 mg/m(2) oral paclitaxel 7 h apart in combination with 10 or 5 mg/kg CsA. Dose reduction of CsA from 10 to 5 mg/kg resulted in a statistically significant decrease in the area under the plasma concentration-time curve (AUC) and time above the threshold concentrations of 0.1 microM (T>0.1 microM) of oral paclitaxel. The mean (+/-SD) AUC and T>0.1 microM values of oral paclitaxel with CsA 10 mg/kg were 4.29+/-0.88 microM x h and 12.0+/-2.1 h, respectively. With CsA 5 mg/kg these values were 2.75+/-0.63 microM x h and 7.0+/-2.1 h, respectively (p=0.028 for both parameters). In conclusion, dose reduction of CsA from 10 to 5 mg/kg resulted in a significant decrease in the AUC and T>0.1 microM values of oral paclitaxel. Because CsA 10 mg/kg resulted in similar paclitaxel AUC and T>0.1 microM values compared to CsA 15 mg/kg (data which we have published previously), the minimally effective dose of CsA is determined at 10 mg/kg.

Metabolism and excretion of paclitaxel after oral administration in combination with cyclosporin A and after i.v. administration

The objective of this study was to compare the quantitative excretion of paclitaxel and metabolites after i.v. and oral drug administration. Four patients received 300 mg/m2 paclitaxel orally 30 min after 15 mg/kg oral cyclosporin A, co-administered to enhance the uptake of paclitaxel. Three weeks later these and three other patients received 175 mg/m2 paclitaxel by i.v. infusion. Blood samples, urine and feces were collected up to 48-96 h after administration, and analyzed for paclitaxel and metabolites. The area under the plasma concentration-time curve of paclitaxel after i.v. administration (175 mg/m2) was 16.2 +/- 1.7 microM x h and after oral administration (300 mg/m2) 3.8 +/- 1.5 microM x h. Following i.v. infusion of paclitaxel, total fecal excretion was 56 +/- 25%, with the metabolite 6alpha-hydroxypaclitaxel being the main excretory product (37 +/- 18%). After oral administration of paclitaxel, total fecal excretion was 76 +/- 21%, of which paclitaxel accounted for 61 +/- 14%. In conclusion, after i.v. administration of paclitaxel, excretion occurs mainly in the feces with the metabolites as the major excretory products. Orally administered paclitaxel is also mainly excreted in feces but with the parent drug in highest amounts. We assume that this high amount of parent drug is due to incomplete absorption of orally administered paclitaxel from the gastrointestinal tract.

Sequence-dependent toxicity profile in modified FAMTX (fluorouracil-adriamycin-methotrexate) chemotherapy with lenograstim support for advanced gastric cancer: a feasibility study

For advanced irresectible gastric cancer, sequential high-dose methotrexate and 5-fluorouracil (both on day 1) combined with adriamycin on day 15 (FAMTX regimen), cycled every 28 days, is a fairly effective but toxic treatment, with a high incidence of neutropenic fever, dose reductions and dose delays. In order to improve FAMTX toxicity, we studied the feasibility of two modified FAMTX regimens with lenograstim support. Seven advanced gastric cancer patients were treated with all three FAMTX drugs on day 1 followed by lenograstim 150 microgm(-2)for 10 days, in 21-day cycles (FUMA regimen). The next seven patients were treated with the same drugs at the same doses, but with adriamycin 1 day prior to methotrexate and 5-fluorouracil administration (AFUM regimen). Patients were monitored for toxicity, response, and survival. The total number of courses was 27 for FUMA and 35 for AFUM with a median of four courses per patient in each cohort. In the FUMA regimen, considerable toxicity consisting of mucositis and fatigue as well as grade 4 neutropenia occurred, and forced four out of seven patients to stop treatment. The consecutive AFUM regimen showed only mild toxicity, and all patients could finish treatment without dose reductions or delays. We found unanticipated and probably sequence-dependent toxicity profiles in two investigational, modified FAMTX schedules with lenograstim support, leading to high rates of dose-limiting toxicity in the FUMA regimen as opposed to mild toxicity in the AFUM regimen, even though the same total drug doses and treatment cycle length (dose intensity) were employed.

Successful treatment with paclitaxel of a patient with metastatic extra-adrenal pheochromocytoma (paraganglioma). A case report and review of the literature

This case report describes the history of a patient with an aggressive course of a metastatic extra-adrenal pheochromocytoma (paraganglioma) who received different combination chemotherapy regimens with no or short-lasting clinical benefit. However, during treatment with single-agent paclitaxel, there was a significant clinical improvement, a partial biochemical response and a minor roentgenologic response, which was sustained for 1 year. In this report we present this case and also review the literature on the chemotherapy used for this rare disease over the past 15 years. To enable the activity of paclitaxel against this neoplasm to be determined, more patients need to be treated.

Phase I and pharmacokinetic study of oral paclitaxel

PURPOSE

To investigate dose escalation of oral paclitaxel in combination with dose increment and scheduling of cyclosporine (CsA) to improve the systemic exposure to paclitaxel and to explore the maximum-tolerated dose (MTD) and dose-limiting toxicity (DLT).

PATIENTS AND METHODS

A total of 53 patients received, on one occasion, oral paclitaxel in combination with CsA, coadministered to enhance the absorption of paclitaxel, and, on another occasion, intravenous paclitaxel at a dose of 175 mg/m(2) as a 3-hour infusion.

RESULTS

The main toxicities observed after oral intake of paclitaxel were acute nausea and vomiting, which reached DLT at the dose level of 360 mg/m(2). Dose escalation of oral paclitaxel from 60 to 300 mg/m(2) resulted in significant but less than proportional increases in the plasma area under the concentration-time curve (AUC) of paclitaxel. The mean AUC values +/- SD after 60, 180, and 300 mg/m(2) of oral paclitaxel were 1.65 +/- 0.93, 3.33 +/- 2.39, and 3.46 +/- 1.37 micromol/L.h, respectively. Dose increment and scheduling of CsA did not result in a further increase in the AUC of paclitaxel. The AUC of intravenous paclitaxel was 15.39 +/- 3.26 micromol/L.h.

CONCLUSION

The MTD of oral paclitaxel was 300 mg/m(2). However, because the pharmacokinetic data of oral paclitaxel, in particular at the highest doses applied, revealed nonlinear pharmacokinetics with only a moderate further increase of the AUC with doses up to 300 mg/m(2), the oral paclitaxel dose of 180 mg/m(2) in combination with 15 mg/kg oral CsA is considered most appropriate for further investigation. The safety of the oral combination at this dose level was good.

Coadministration of oral cyclosporin A enables oral therapy with paclitaxel

i.v. paclitaxel is inconvenient and associated with significant and poorly predictable side effects largely due to the pharmaceutical vehicle Cremophor EL. Oral administration may be attractive because it may circumvent the use of Cremophor EL. However, paclitaxel, as well as many other commonly applied drugs, has poor bioavailability caused by high affinity for the mdrl P-glycoprotein drug efflux pump, which is abundantly present in the gastrointestinal tract. Consequently, inhibition of P-glycoprotein by oral cyclosporin A (CsA) should increase systemic exposure of oral paclitaxel to therapeutic levels. A proof-of-concept study was carried out in 14 patients with solid tumors. Patients received one course of oral paclitaxel of 60 mg/m2 with or without 15 mg/kg CsA and with i.v. paclitaxel in subsequent courses. The pharmacokinetics of paclitaxel and its major metabolites were determined during the first two courses. In addition, levels of CsA, Cremophor EL, and ethanol were measured. Bioavailability of oral paclitaxel in combination with CsA was 8-fold higher than after oral paclitaxel alone (P<0.001). Therapeutic concentrations were achieved on average during 7.4 h, which is comparable with an equivalent i.v. dose. The oral combination was well tolerated and did not induce gastrointestinal toxicity or myelosuppression. Cremophor EL plasma levels after oral drug administration were undetectable. In conclusion, coadministration of oral CsA increased the systemic exposure of oral paclitaxel from negligible to therapeutic levels. The combination enables treatment with oral paclitaxel. Undetectable Cremophor EL levels after oral administration may have a very beneficial influence on the safety of the treatment with oral paclitaxel.

Blood volume determination by the carbon monoxide method using a new delivery system: accuracy in critically ill humans and precision in an animal model

OBJECTIVE

To evaluate accuracy and repeatability of blood volume determinations made by the carbon monoxide method, using a ventilator-driven administration system.

DESIGN

Prospective within-patient comparison, using simultaneous measurements by two methods to determine accuracy. Prospective laboratory investigation in animals to estimate repeatability.

SUBJECTS

For accuracy: Nineteen ventilated critically ill patients in a university hospital intensive care unit. For repeatability: Six anesthetized, mechanically ventilated normovolemic pigs because this is impossible to perform in humans.

INTERVENTIONS

In the accuracy study, a small mass of carbon monoxide was administered via a closed breathing system and arterial blood samples were taken from existing cannulas. In the repeatability study, an intramuscular sedative was given, followed by an inhalational anesthetic induction and mechanical ventilation via a tracheal tube. Left axillary artery and external jugular vein cannulas were sited. Anesthesia was maintained using an intravenous infusion. Five sequential circulating hemoglobin and blood volume estimations were made using the carbon monoxide method.

MEASUREMENTS AND MAIN RESULTS

The small carboxyhemoglobin increase produced by uptake of a small, known mass of carbon monoxide was used to estimate the circulating blood volume. Simultaneous measurement, using 51Cr-labeled red blood cells, was performed. Twenty measurements were made in 19 patients. The bias (mean difference between blood volume measurements by the two methods) was 397 mL (5.53 mL x kg(-1)) +/-415 mL (+/-5.95 mL x kg(-1)); the limits of agreement (mean difference +/-2 SD) were -433 mL and 1227 mL (-6.36 mL x kg(-1) and 17.42 mL x kg(-1)). Therefore, 95% of expected differences will lie between these limits. The mean blood volume was 75.8 mL x kg(-1) in the animals. The coefficient of variation of repeated estimates was 9.49%. Mean circulating hemoglobin mass was 7.31 mmol with a coefficient of variation of 10.18%. The mean hemoglobin concentration, by co-oximetry, was 5.014 mmol x L(-1), coefficient of variation, 2.99%.

CONCLUSION

This arrangement is a potential bedside method of estimating blood volume and circulating hemoglobin mass. We have rendered the technique more acceptable clinically by creating a ventilator-driven administration system.

Pharmacokinetics of paclitaxel administered as a 3-hour or 96-hour infusion

AIM

To investigate the pharmacokinetics of paclitaxel (Paxene) administered to patients with advanced breast or ovarian cancer and to document safety and anti-tumour activity in this study population.

PATIENTS AND METHODS

Patients with advanced breast or ovarian cancer were accrued to two clinical studies. Paclitaxel (Paxene) was administered as a 3-h 175 mg m-2 or as a 96-h 140 mg m-2(105 mg m-2 in the presence of liver metastases) infusion. Patients not responding to the 3-h schedule were permitted to cross-over to the 96-h schedule. The data were compared to those of five patients who were previously treated with paclitaxel administered as Taxol (140 mg m-296-h infusion) at our Institute.

RESULTS

Fourteen patients with breast cancer and five ovarian cancer patients were entered into this study. Seven patients received the 3-h regimen, and 12 were assigned to the 96-h schedule. Five patients originally treated with the 3-h schedule, crossed over to the 96-h arm. For the 3-h 175 mg m-2 dose, the area under the plasma concentration vs time curve (AUC) was (mean+/-SD) 16.9+/-4.8 h x micromol x l-1, whereas the AUCs were 5.5+/-1.2 and 4.3+/-0.9 h x micromol x l-1 for the 96-h 140 mg m-2 and 105 mg m-2 doses, respectively. The clearance of paclitaxel was independent of the dose in the 96-h group, indicating linear pharmacokinetics. Pharmacokinetics of Paxene (96-h 140 mg m-2) were not significantly different from the kinetics after Taxol (96-h 140 mg m-2) administration.

Phase I and pharmacokinetic study of irinotecan administered as a low-dose, continuous intravenous infusion over 14 days in patients with malignant solid tumors

PURPOSE

To evaluate the feasibility of administering irinotecan as a continuous intravenous infusion for 14 to 21 days.

PATIENTS AND METHODS

Patients with solid tumors refractory to standard therapy received continuous infusions of irinotecan by means of an ambulatory infusion pump. The starting dosage was 12.5 mg/m(2)/d for 14 days every 3 weeks. After identification of the maximum-tolerated dose for the 14-day infusion schedule, the protocol was amended to prolong the infusion duration to 17 and 21 days. Pharmacokinetics of irinotecan and SN-38 and its glucuronide were determined using high-performance liquid chromatography and noncompartmental modeling.

RESULTS

Thirty-three patients received 85+ courses. At the first dose level (12.5 mg/m(2)/d), cumulative grade 3 or 4 diarrhea and grade 3 or 4 neutropenia occurred in three of five patients. At a dosage of 10 mg/m(2)/d, 14-day administration resulted in grade 4 diarrhea in two of six patients and one episode of grade 4 vomiting occurred, whereas with 17-day administration, one episode of grade 3 nausea and two episodes of grade 3 or 4 diarrhea were observed in six patients. Increasing the number of days of infusion to 21 days was not feasible because of cumulative diarrhea. Hematologic toxicity was rare. The mean metabolic SN-38 area under the curve/irinotecan area under the curve ratio was 16% +/- 6% compared with 3% to 5% after short infusion schedules involving therapeutic dosages. Partial responses were observed in two patients with extraovarian and colorectal cancer.

CONCLUSION

The recommended dosage is 10 mg/m(2)/d for 14 days, repeated every 3 weeks. Enhanced metabolism of irinotecan to SN-38 may explain in part the low recommended dose for this schedule.

Measuring brain tissue oxygenation compared with jugular venous oxygen saturation for monitoring cerebral oxygenation after traumatic brain injury

Jugular bulb oximetry is the most widely used method of monitoring cerebral oxygenation. More recently, measurement of brain tissue oxygenation has been reported in head-injured patients. We compared the changes in brain tissue oxygen partial pressure (PbO2) with changes in jugular venous oxygen saturation (SjVO2) in response to hyperventilation in areas of brain with and without focal pathology. Thirteen patients with severe head injuries were studied. A multiparameter sensor was inserted into areas of brain with focal pathology in five patients and outside areas of focal pathology in eight patients. A fiberoptic catheter was inserted into the right jugular bulb. Patients were hyperventilated in a stepwise manner from a PaCO2 of approximately 35 mm Hg to a PaCO2 of 22 mm Hg. There was no significant change in cerebral perfusion pressure or arterial partial pressure of oxygen with hyperventilation. In areas without focal pathology, there was a good correlation between changes in SjVO2 and PbO2 (deltaSjVO2 and deltaPbO2; r2 = 0.69, P < 0.0001). In areas with focal pathology, there was no correlation between deltaSjVO, and APbO2 (r2 =0.07, P = 0.23). In this study, we demonstrated that measurement of local tissue oxygenation can highlight focal differences in regional cerebral oxygenation that are disguised when measuring SjVO2. Thus, monitoring of PbO2 is a useful addition to multimodal monitoring of patients with traumatic head injury.

IMPLICATIONS

Brain oxygenation is currently monitored by using jugular bulb oximetry, which attracts a number of potential artifacts and may not reflect regional changes in oxygenation. We compared this method with measurement of brain tissue oxygenation using a multiparameter sensor inserted into brain tissue. The brain tissue monitor seemed to reflect regional brain oxygenation better than jugular bulb oximetry.

Effects of low-dose isoflurane on saccadic eye movement generation

The effects of 0.15% quasi-steady-state end-tidal isoflurane on two saccadic eye-movement tests were examined in five volunteers using a newly devised computer-based recording system. The tests were saccadic latency and a countermanding task, the latter being an indicator of the highest levels of conscious performance. A moving light-emitting diode target was displayed on a screen and in the saccadic-latency task the latency of eye movement to the target was measured. In all five subjects the latency increased with anaesthetic by an amount which varied from 8 to 45 ms. This result was significantly different (p < 0.05) from subjects without anaesthetic. In the countermanding task, the subject had to voluntarily inhibit movement to the target. Again anaesthetic increased the latency of response, which varied from 6 to 33 ms. This result was significantly different (p < 0.05) from subjects without anaesthetic. In these studies it appeared that two tasks, one a simple latency test and the other, the countermanding task, requiring higher cortical processing were equally impaired at subanaesthetic concentrations of isoflurane.

Ease of insertion of the laryngeal mask airway by inexperienced personnel when using an introducer

The Portex introducer for the laryngeal mask airway was designed as an aid to successful insertion, acting as an idealised 'artificial hard palate' to guide the tip of the laryngeal mask into the correct position. A number of authors have investigated laryngeal mask insertion by unskilled personnel in certain situations, one example being nurses during in-hospital cardiopulmonary resuscitation. We investigated whether the introducer had any effect on the incidence of first-time successful LMA placement by unskilled personnel. These were nonanaesthetist doctors, randomly assigned to have one attempt at LMA insertion in an anaesthetised patient, with and without the introducer. In 44 patients with the LMA being inserted according to the manufacturer's instructions, there was a 68% success rate (14 failures). In 45 patients with the LMA being inserted with the aid of a Portex introducer, there was a 96% success rate (two failures). This was a highly significant improvement (p < 0.001).

Intrathecal morphine for caesarean section: an assessment of pain relief, satisfaction and side-effects

In a prospective, randomised, double-blind study of 60 patients who had an elective Caesarean section under spinal anaesthesia we compared 0.1 mg intrathecal morphine with intrathecal saline placebo. All patients received morphine intravenously by patient-controlled analgesia after the operation. Pain, satisfaction and side-effects were assessed at 4 and 24 h after the operation. Pain measured by a 100-mm visual analogue scale was less in the intrathecal morphine group at both times (p < 0.05) and morphine consumption was lower (p < 0.01). At 4 h the intrathecal morphine group had more pruritus (p < 0.001) but there was no difference in satisfaction. At 24 h there was no significant difference in side-effects, but overall satisfaction measured by visual analogue scale was better in the intrathecal morphine group (p < 0.01). Intrathecal morphine improves pain relief and patient satisfaction after Caesarean section.

Safety of bronchoalveolar lavage in the critically ill, mechanically ventilated patient

OBJECTIVE

To assess complications of bronchoalveolar lavage in the intubated, mechanically ventilated patient.

DESIGN

A retrospective, consecutive case series.

SETTING

Medical, surgical, and bone marrow transplant critical care units at a university teaching hospital.

PATIENTS

Ninety-nine consecutive critically ill, mechanically ventilated patients undergoing bronchoalveolar lavage were included in the study.

INTERVENTIONS

All patients underwent bronchoalveolar lavage using a standard method designed to maximize the safety of the procedure.

MEASUREMENTS

Each patient's hospital chart was reviewed for immediate and delayed medical complications of the procedure, including cardiac arrhythmias, bleeding, and hemodynamic disturbances. Specific indices of lung mechanics (peak inspiratory airway pressure and static compliance) and oxygenation (alveolar to arterial oxygen tension gradient [P(A-a)O2] and the ratio of FIO2/PaO2) were measured before and 4 hrs after bronchoalveolar lavage to assess durable physiologic consequences of the procedure.

RESULTS

No complications occurred that required premature termination of bronchoalveolar lavage. Three patients exhibited adverse effects (hypotension in two and wheezing in one) immediately after the procedure, all of which resolved promptly with treatment. No statistically significant changes were observed in the variables of arterial oxygenation or pulmonary mechanics. Although the sample mean did not change significantly for any of the oxygen variables, 19% of the patients experienced widening of the P(A-a)O2 by greater than 100 torr (greater than 13.3 kPa). A systematic analysis indicated that there was no statistically significant relationship between readily available clinical variables (including duration of mechanical ventilation before bronchoalveolar lavage and prebronchoalveolar lavage P[A-a]O2), and deterioration in oxygenation after the procedure.

CONCLUSIONS

We conclude that bronchoalveolar lavage is a well-tolerated procedure in critically ill, mechanically ventilated patients, provided that risk factors for complications are corrected before the procedure and one adheres to procedural guidelines focused on patient safety. Clinically important complications are uncommon. Some patients exhibit deterioration in oxygen after bronchoalveolar lavage; this occurrence cannot be predicted before the procedure.