Correlation of extent of ALK FISH positivity and crizotinib efficacy in three prospective studies of ALK-positive patients with non-small-cell lung cancer

Background

In clinical trials of patients with anaplastic lymphoma kinase (ALK)-positive non-small-cell lung cancer (NSCLC) treated with crizotinib, evaluation of the relationship between the percentage of ALK-positive cells by fluorescence in situ hybridization (FISH)-particularly near the cut-off defining positive status-and clinical outcomes have been limited by small sample sizes.

Patients and methods

Data were pooled from three large prospective trials (one single-arm and two randomized versus chemotherapy) of crizotinib in patients with ALK-positive NSCLC determined by Vysis ALK Break Apart FISH using a cut-off of ≥15% ALK-positive cells. Logistic regression and proportional hazards regression analyses were used to explore the association of percent ALK-positive cells with objective response and progression-free survival (PFS), respectively.

Results

Of 11 081 screened patients, 1958 (18%) were ALK positive, 7512 (68%) were ALK negative, and 1540 (14%) were uninformative. Median percentage of ALK-positive cells was 58% in ALK-positive patients and 2% in ALK-negative patients. Of ALK-positive patients, 5% had 15%-19% ALK-positive cells; of ALK-negative patients, 2% had 10%-14% ALK-positive cells. Objective response rate for ALK-positive, crizotinib-treated patients with ≥20% ALK-positive cells was 56% (n = 700/1246), 55% (n = 725/1312) for those with ≥15% ALK-positive cells, and 38% for those with 15%-19% ALK-positive cells (n = 25/66). As a continuous variable, higher percentages of ALK-positive cells were estimated to be associated with larger differences in objective response and PFS between crizotinib and chemotherapy; however, tests for interaction between treatment and percentage of ALK-positive cells were not significant (objective response, P = 0.054; PFS, P = 0.17).

Conclusions

Patients with ALK-positive NSCLC benefit from treatment with crizotinib across the full range of percentage of ALK-positive cells, supporting the clinical utility of the 15% cut-off. The small number of patients with scores near the cut-off warrant additional study given the potential for misclassification of ALK status due to technical or biologic reasons.

Crizotinib in ROS1-rearranged advanced non-small-cell lung cancer (NSCLC): updated results, including overall survival, from PROFILE 1001

BACKGROUND

In the ongoing phase I PROFILE 1001 study, crizotinib showed antitumor activity in patients with ROS1-rearranged advanced non-small-cell lung cancer (NSCLC). Here, we present updated antitumor activity, overall survival (OS) and safety data (additional 46.2 months follow-up) for patients with ROS1-rearranged advanced NSCLC from PROFILE 1001.

PATIENTS AND METHODS

ROS1 status was determined by FISH or reverse transcriptase-polymerase chain reaction. All patients received crizotinib at a starting dose of 250 mg twice daily.

RESULTS

Fifty-three patients received crizotinib, with a median duration of treatment of 22.4 months. At data cut-off, treatment was ongoing in 12 patients (23%). The objective response rate (ORR) was 72% [95% confidence interval (CI), 58% to 83%], including six confirmed complete responses and 32 confirmed partial responses; 10 patients had stable disease. Responses were durable (median duration of response 24.7 months; 95% CI, 15.2-45.3). ORRs were consistent across different patient subgroups. Median progression-free survival was 19.3 months (95% CI, 15.2-39.1). A total of 26 deaths (49%) occurred (median follow-up period of 62.6 months), and of the remaining 27 patients (51%), 14 (26%) were in follow-up at data cut-off. Median OS was 51.4 months (95% CI, 29.3 to not reached) and survival probabilities at 12, 24, 36, and 48 months were 79%, 67%, 53%, and 51%, respectively. No correlation was observed between OS and specific ROS1 fusion partner. Treatment-related adverse events (TRAEs) were mainly grade 1 or 2, per CTCAE v3.0. There were no grade ≥4 TRAEs and no TRAEs associated with permanent discontinuation. No new safety signals were reported with long-term crizotinib treatment.

CONCLUSIONS

These findings serve as a new benchmark for OS in ROS1-rearranged advanced NSCLC, and continue to show the clinically meaningful benefit and safety of crizotinib in this molecular subgroup.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov identifier NCT00585195.

Current status of targeted therapy for anaplastic lymphoma kinase-rearranged non-small cell lung cancer

The identification of chromosomal rearrangements involving the anaplastic lymphoma kinase (ALK) gene in ~3-5% of non-small cell lung cancer (NSCLC) tissues and the demonstration that the first-in-class ALK tyrosine kinase inhibitor, crizotinib, can effectively target these tumors represent a significant advance in the evolution of personalized medicine for NSCLC. Single-arm studies demonstrating rapid and durable responses in the majority of ALK-positive NSCLC patients treated with crizotinib have been followed by a randomized phase III clinical trial in which superiority of crizotinib over chemotherapy was seen in previously treated ALK-positive NSCLC patients. However, despite the initial responses, most patients develop acquired resistance to crizotinib. Several novel therapeutic approaches targeting ALK-positive NSCLC are currently under evaluation in clinical trials, including second-generation ALK inhibitors, such as LDK378, CH5424802 (RO5424802802), and AP26113, and heat shock protein 90 inhibitors.

Pharmacokinetics/genotype associations for major cytochrome P450 enzymes in native and first- and third-generation Japanese populations: comparison with Korean, Chinese, and Caucasian populations

Application of foreign clinical data across geographic regions can accelerate drug development. Drug disposition can be variable, and identification of factors influencing responsible pharmacokinetic/pharmacogenomic approaches could facilitate the universal application of foreign data and reduce the total amount of phase III clinical trials evaluating risks in different populations. Our objective was to establish and compare genotype (major cytochrome P450 (CYP) enzymes)/phenotype associations for Japanese (native and first- and third-generation Japanese living abroad), Caucasian, Chinese, and Korean populations using a standard drug panel. The mean metabolic ratios (MRs) for the four ethnic groups were similar except for a lower activity of CYP2D6 in Caucasians and CYP2C19 in Asians. Genotype, not ethnicity, impacted the MR for CYP2C9, CYP2C19, and CYP2D6; neither affected CYP1A2, CYP2E1, and CYP3A4/5 activities. We conclude that equivalent plasma drug concentrations and metabolic profiles can be expected for native Japanese, first- and third-generation Japanese, Koreans, and Chinese for compounds handled through these six CYP enzymes.

A double-blind, placebo-controlled study of the safety, tolerability and pharmacokinetics of CP-101,606 in patients with a mild or moderate traumatic brain injury

CP-101,606 is a postsynaptic antagonist of the glutamate-mediated NR2B subunit of the N-methyl-D-aspartate (NMDA) receptor. When administered intravenously (i.v.) at the time of injury, CP-101,606 is neuroprotective in animal models of traumatic brain injury (TBI) and ischemia. Minimal adverse effects have been observed in normal human volunteers given i.v. doses of up to 3 mg/kg/hr for 72 hours. The objective of the present clinical trial was to assess the safety, pharmacokinetics, and tolerability of CP-101,606 infused for various times in patients who had suffered either an acute moderate or mild TBI (Glasgow Coma Score 9-14) or hemorrhagic stroke. Patients began receiving treatment within 12 hours of brain injury. A total of 53 subjects (45 with TBI and 8 with stroke) were randomized in a double-blind fashion to receive CP-101,606 or placebo (4 drug: 1 placebo). Drug/placebo was administered by i.v. infusion (0.75 mg/kg/hr) for 2 hours and then stopped (n = 25) or continued for 22 hours (n = 4) or 70 hours (n = 24) at a rate of 0.37 mg/kg/hr. Mean plasma drug concentrations were well above the predicted therapeutic concentration of 200 ng/ml within two hours of initiating treatment and were sustained as long as drug was infused. All the patients tolerated their drug/placebo treatment, and there were no clinically significant cardiovascular or hematological abnormalities in either group. A Neurobehavioral Rating Scale, used to detect personality changes and behavioral disturbances, indicated that all subjects showed an improvement from their postinjury, predosing baseline but did not significantly differ from each other with respect to type of head injury and/or treatment with drug or placebo. Modified Kurtzke Scoring also showed a similar pattern of improvement irrespective of type of head injury or drug/placebo treatment. This study suggests that CP-101,606, infused for up to 72 hours has no psychotropic effects and is well-tolerated in patients who have sustained a mild or moderate TBI or hemorrhagic stroke.

An open-label study of CP-101,606 in subjects with a severe traumatic head injury or spontaneous intracerebral hemorrhage

CP-101,606 is a postsynaptic antagonist of N-methyl-D-aspartate (NMDA) receptors bearing the NR2B subunit. When administered intravenously (i.v.), it decreases the effects of traumatic brain injury (TBI) and focal ischemia in animal models. Therapeutic plasma concentrations (200 ng/ml) in animals, have been well tolerated in healthy human volunteers. The purpose of the present dose escalation study was to assess the safety, tolerability, and pharmacokinetics of CP-101,606 in subjects who had suffered either an acute severe TBI (Glasgow Coma Scale 3-8) or spontaneous intracerebral hemorrhage. Thirty patients, 20 with a TBI and 10 with a stroke, were enrolled in the trial and began receiving an i.v. infusion of CP-101,606 for 2 hours, 24 hours, or 72 hours within 12 hours of brain injury. For the first two hours, the drug was given a rate of 0.75 mg/kg/hr and then stopped (n = 17) or continued for 22 (n = 2) or 70 hours (n = 11) at 0.37 mg/kg/hr. Plasma and cerebrospinal fluid (CSF) were collected at serial times during and after treatment. There were no consistent changes in blood pressure or pulse nor any clinically significant hematological or electrocardiogram (ECG) abnormalities attributable to CP-101,606. No adverse events or behavioral changes were considered to be related to the drug. Plasma concentrations of CP-101,606 over 200 ng/ml were rapidly achieved in the blood and CSF within two hours and were sustained there as long as the drug was infused. CSF concentrations were slightly higher than that in plasma by the end of infusion suggesting good penetration of CP-101,606 into the CSF. Outcome in the severe TBI patients, as measured by the Glasgow Outcome Score at six months, suggested that a two-hour infusion yielded a range of scores similar to contemporary patients with a severe TBI treated at our hospital while the outcomes of the patients treated with either a 24- or 72-hour infusion were better on average. Thus, these results indicate that CP-101,606 infused for up to 72 hours is well tolerated, penetrates the CSF and brain, and may improve outcome in the brain-injured patient.

The pharmacokinetics of ziprasidone in subjects with normal and impaired renal function

AIMS

To assess whether renal impairment influences the pharmacokinetics of ziprasidone, and to determine whether ziprasidone is cleared via haemodialysis.

METHODS

Thirty-nine subjects with varying degrees of renal impairment were enrolled into an open-label, multicentre, multiple-dose study and assigned to four groups according to their renal function: normal (group 1, creatinine clearance > 70 ml min(-1); mildly impaired (group 2, creatinine clearance 30-60 ml min(-1); moderately impaired (group 3, creatinine clearance 10-29 ml min(-1), and severely impaired (group 4, requiring haemodialysis three times-a-week). Subjects received ziprasidone 40 mg day(-1), given orally with food, as two divided daily doses for 7 days and a single 20 mg dose on the morning of day 8. Pharmacokinetic variables were determined from multiple venous blood samples collected on days 1 and 8 (haemodialysis day for subjects with severe renal impairment). Additional samples were collected from subjects with severe renal impairment on day 7 (nonhaemodialysis day).

RESULTS

On day 1 there were no statistically significant differences in the pharmacokinetics (AUC(0, 12 h), Cmax, tmax) of ziprasidone among subjects with normal renal function and those with mild, moderate and severe renal impairment. The AUC(0,12 h) and Cmax in subjects with mildly impaired renal function were statistically significantly greater than in those with moderately impaired renal function (P = 0.0163-0.0385). The mean AUC(0,12 h) was 272, 370, 250 and 297 ng ml(-1) h in groups 1, 2, 3 and 4, respectively. Corresponding mean Cmax values were 47, 61, 41 and 50 ng ml(-1) and corresponding mean tmax values were 5, 6, 5 and 5 h. On day 8 there were no statistically significant differences in the pharmacokinetics (AUC(0,12 h), Cmax, tmax, lambda(z), Fb) of ziprasidone among subjects with normal renal function and those with moderate or severe renal impairment. The AUC(0,12 h) in subjects with mild renal impairment was statistically significantly greater than those in the other three groups (P = 0.0025-0.0221), but this was not considered clinically significant. The mean AUC(0,12 h) were 446, 650, 389 and 427 ng ml(-1) h in groups 1, 2, 3 and 4, respectively. Corresponding mean Cmax values were 68, 93, 54 and 70 ng ml(-1), corresponding mean tmax values were 4, 5, 4 and 5 h and corresponding mean lambda(z) were 0.14, 0.11, 0.14 and 0.17 h(-1). The mean percentage Fb was 99.84-99.88% across all groups and the mean t(1/2),z ranged from 4.2 to 6.4 h. Comparison of the mean AUC(0,12 h) and Cmax values in subjects with severe renal impairment on day 7 with those on day 8 suggested that haemodialysis does not have a clinically significant effect on the pharmacokinetics of ziprasidone.

CONCLUSIONS

The findings of this study indicate that mild-to-moderate impairment of renal function does not result in clinically significant alteration of ziprasidone pharmacokinetics and therefore does not necessitate dose adjustment.

The pharmacokinetics of ziprasidone in subjects with normal and impaired hepatic function

AIMS

To assess whether hepatic impairment influences the pharmacokinetics of ziprasidone.

METHODS

Thirty subjects with normal hepatic function or a primary diagnosis of clinically significant cirrhosis (Child-Pugh A or B) were enrolled into an open-label, multicentre, multiple-dose study. The subjects with chronic, stable hepatic impairment and the matched control subjects received ziprasidone 40 mg day(-1), given orally with food, as two divided daily doses for 4 days and a single 20 mg dose on the morning of day 5. Pharmacokinetic variables were determined from multiple venous blood samples collected on days 1 and 5. Liver function was evaluated quantitatively using antipyrine.

RESULTS

On day 1 there were no statistically significant differences in the pharmacokinetics (AUC(0,12 h), Cmax, tmax) of ziprasidone between the two groups. On day 5 there were no statistically significant differences in the Cmax or tmax for ziprasidone between the two groups. The mean AUC(0,12 h) for ziprasidone was statistically significantly greater in the hepatically impaired subjects compared with the normal subjects (590 ng ml(-1) h vs. 467 ng ml(-1) h, P = 0. 042). However, the AUC(0,12 h) increased by only 26% in the cirrhotic group compared with the matched control group. The ziprasidone lambda(z) in the subjects with normal hepatic function was statistically significantly greater than that in the hepatically impaired subjects (P<0.001). There was no correlation between antipyrine lambda(z) and ziprasidone lambda(z) in the subjects with normal hepatic function or in those with hepatic impairment.

CONCLUSIONS

The findings of this study indicate that mild to moderate hepatic impairment does not result in clinically significant alteration of ziprasidone pharmacokinetics.

The pharmacokinetics of ziprasidone in healthy volunteers treated with cimetidine or antacid

AIMS

To evaluate the effects of cimetidine and Maalox(R) (aluminium hydroxide 1.35 g and magnesium hydroxide 1.2 g) on the pharmacokinetics of ziprasidone.

METHODS

Eleven healthy young subjects aged 18-45 years were given single oral doses of ziprasidone 40 mg on three occasions at least 7 days apart. On one occasion ziprasidone was administered alone, on another occasion ziprasidone was co-administered with oral cimetidine 800 mg and on a third occasion ziprasidone was co-administered with oral Maalox(R).

RESULTS

The administration of cimetidine increased the ziprasidone AUC(0,infinity) by 6% but there were no statistically significant differences in Cmax, tmax or lambda(z) between the ziprasidone+cimetidine group and the ziprasidone group. The administration of Maalox did not produce any statistically significant differences in AUC(0,infinity), Cmax, tmax or lambda(z) between the ziprasidone+Maalox group and the ziprasidone group.

CONCLUSIONS

The pharmacokinetics of ziprasidone are not affected by concurrent administration of cimetidine or Maalox. This suggests that other nonspecific inhibitors of cytochrome P450 and antacids are unlikely to alter the pharmacokinetics of ziprasidone.

Single- and multiple-dose pharmacokinetics of ziprasidone under non-fasting conditions in healthy male volunteers

AIMS

To evaluate the pharmacokinetics and tolerability of single and multiple oral doses of ziprasidone in healthy male volunteers, and to determine the influence of ziprasidone on serum prolactin levels.

METHODS

Single and multiple doses of ziprasidone were given orally (as two divided daily doses), at fixed dosages of 10 and 40 mg day(-1), and using titrated regimens of 40-80 and 40-120 mg day(-1), for 14 days. All dosages were taken immediately after food. The study adopted a randomized, double-blind, placebo-controlled design. Prolactin response, sedative properties, tolerability, and extrapyramidal symptoms were also investigated.

RESULTS

Steady-state exposure to ziprasidone was attained after 1 day of dosing. Mean Cmax and AUC(0,12 h) increased with increasing dose, with apparent dose-proportionality between the 20 and 60 mg dose levels. Trough-to-peak ratios at steady state ranged from 2 to 5. Accumulation ratios for the fixed-dose regimens were 1.49 and 1.48 at the 5 and 20 mg dose levels, respectively. Ziprasidone was associated with transient prolactin elevation but levels of prolactin returned to baseline within the dosing interval at steady state. There was a marginal, transient increase in serum prolactin levels which was not dose-related at the 80 and 120 mg day(-1) doses, and which was noted to attenuate with chronic dosing. Ziprasidone was generally well tolerated. The most frequent side-effect was mild or moderate headache. A minority of patients suffered first-dose postural hypotension. Ziprasidone was also associated with a mild sedative effect that became less pronounced as treatment continued. There were no drug-related changes in electrocardiogram or clinical laboratory variables that were of clinical importance.

CONCLUSIONS

Ziprasidone is characterized by a predictable pharmacokinetic profile resulting in symptoms that reflect its pharmacological action.

Ziprasidone and the activity of cytochrome P450 2D6 in healthy extensive metabolizers

AIMS

To determine whether ziprasidone alters the metabolizing activity of the 2D6 isoenzyme of cytochrome P450 (CYP2D6).

METHODS

Twenty-four healthy young subjects aged 18-45 years were screened for CYP2D6 metabolizing activity and shown to be extensive metabolizers of dextromethorphan. These subjects were then randomized to receive a single dose of ziprasidone 80 mg, paroxetine 20 mg or placebo, 2 h before receiving a dose of dextromethorphan. Urine samples for the determination of dextromethorphan concentrations were collected over the 8 h period following dextromethorphan dosing, and used for the determination of dextromethorphan/dextrorphan ratios. Blood samples were collected immediately before and up to 10 h after the administration of ziprasidone or paroxetine, and used to derive pharmacokinetic parameters of ziprasidone and paroxetine.

RESULTS

There were no statistically significant changes in the urinary dextromethorphan/dextrorphan ratio in the ziprasidone group or the placebo group. By contrast, there was a 10-fold increase in the urinary dextromethorphan/dextrorphan ratio in the paroxetine group and this differed significantly from those in the ziprasidone and placebo groups (P = 0.0001).

CONCLUSIONS

The findings of this study suggest that ziprasidone does not inhibit the clearance of drugs metabolized by CYP2D6.

The effects of ziprasidone on steady-state lithium levels and renal clearance of lithium

AIMS

To assess the potential of ziprasidone to alter the renal clearance and steady-state serum levels of lithium.

METHODS

Healthy subjects who had stable serum lithium levels during the first 7 days of treatment with lithium 900 mg day(-1), given as two divided daily doses, were randomized to receive concomitant treatment with either ziprasidone, 40 mg day(-1), given as two divided daily doses, on days 9-11 followed by 80 mg day(-1), given as two divided daily doses on days 12-15 (n = 12), or placebo twice daily (n = 13). Ziprasidone or placebo was administered 2 h before each dose of lithium.

RESULTS

Ziprasidone administration was associated with a 0.07 mmol l(-1) (13%) mean increase in steady-state serum lithium levels compared with a mean increase of 0.06 mmol l(-1) (10%) with placebo. Mean renal clearance of lithium decreased by 0.09 l h(-1) (5%) in the ziprasidone group and by 0.14 l h(-1) (9%) in the placebo group. None of these differences between the two groups was statistically or clinically significant.

CONCLUSIONS

Ziprasidone does not alter steady-state serum lithium concentrations or renal clearance of lithium.

Single- and multiple-dose pharmacokinetics of ziprasidone in healthy young and elderly volunteers

AIMS

To compare the pharmacokinetics of ziprasidone in healthy young (18-45 years) men and women, and healthy elderly (> or = 65 years) men and women.

METHODS

Eight young men, 11 young women, 8 elderly men and 8 elderly women were given oral ziprasidone 40 mg day(-1), in two evenly divided daily doses, for 7 days, followed by a single 20 mg dose on day 8. Serum samples were collected immediately before the morning dose on days 1-8, for up to 12 h after dosing on day 1 and for up to 96 h after dosing on day 8. The resulting data were used to derive pharmacokinetic parameters of ziprasidone in each age and gender group.

RESULTS

Steady-state serum concentrations of ziprasidone were achieved within 2-3 days. The steady-state pharmacokinetics of ziprasidone, determined 8 days after the initiation of treatment, were similar in the young men, elderly men and young women. Assessment of gender effects by analysis of variance revealed statistically significant differences in Cmax (85 vs. 69 ng ml(-1) and tmax (3.19 vs. 4.81 h) but no differences in AUC(0,12 h) or lambda(z). Assessment of age effects by analysis of variance revealed statistically significant differences in AUC(0,12 h) (560 vs. 465 ng ml(-1) h), Cmax (85 vs. 69 ng ml(-1) and lambda(z) (0.126 vs. 0.197 l h(-1) but no difference in tmax. Assessment of age and gender effects by analysis of covariance, with body weight as the covariate, did not reveal any significant differences. The mean t(1/2), z in the young men, young women, elderly men and elderly women were 3.1, 4.1, 5.7 and 5.3 h, respectively. Standard deviations of the means for the pharmacokinetic parameters for the elderly women tended to be large.

CONCLUSIONS

The influence of age and gender on the pharmacokinetics of ziprasidone is not clinically significant.

An exploratory haloperidol-controlled dose-finding study of ziprasidone in hospitalized patients with schizophrenia or schizoaffective disorder

Ninety patients with schizophrenia or schizoaffective disorder according to DSM-III-R criteria participated in this double-blind, exploratory, dose-ranging trial. After a single-blind washout period of 4 to 7 days, patients were randomly assigned to receive one of four fixed doses of the new antipsychotic, ziprasidone 4 (N = 19), 10 (N = 17), 40 (N = 17), or 160 (N = 20) mg/day or haloperidol 15 mg/day (N = 17) for 4 weeks. A dose-response relationship among ziprasidone groups was established for improvements in Clinical Global Impression Severity (CGI-S) score (p = 0.002) but not in Brief Psychiatric Rating Scale (BPRS) total score (p = 0.08). The intent-to-treat analysis of mean changes from baseline in the BPRS total, BPRS Psychosis core, and CGI-S scores demonstrated that ziprasidone 160 mg/day was comparable with haloperidol in reducing overall psychopathology and positive symptoms and was superior to ziprasidone 4 mg/day. Despite the small sample size and short duration of the trial, the improvement in CGI-S with both ziprasidone 160 mg/day and haloperidol 15 mg/day was statistically significantly greater than with ziprasidone 4 mg/day (p = 0.001 andp = 0.005, respectively). The percentage of patients classified as responders on both the BPRS total (> or = 30% improvement) and CGI-Improvement (score of 1 or 2) scales in the ziprasidone 160 mg/day group was similar to that in the haloperidol group and nonsignificantly greater than that in the ziprasidone 4 mg/day group. On all assessments of clinical efficacy, the improvements associated with ziprasidone 4 mg/day, 10 mg/day, and 40 mg/day were similar. Concomitant benztropine use at any time during the study was less frequent with ziprasidone 160 mg/day (15%) than with haloperidol (53%). Haloperidol was associated with a sustained hyperprolactinemia, unlike ziprasidone, where only transient elevations in prolactin that returned to normal within the dosing interval were observed. Ziprasidone was well tolerated, and the incidence of adverse events was similar in all groups. The results of this study suggest that ziprasidone 160 mg/day is as effective as haloperidol 15 mg/day in reducing overall psychopathology and positive symptoms of an acute exacerbation of schizophrenia or schizoaffective disorder but has a lower potential to induce extrapyramidal symptoms.

Pharmacokinetics and pharmacodynamics of the leukotriene B4 receptor antagonist CP-105,696 in man following single oral administration

AIMS

CP-105,696, (+)-1-(3S,4R)-[3-(4-phenylbenzyl)-4-hydroxy-chroman-7-yl] cyclopropane carboxylic acid is a potent, novel LTB4 receptor antagonist advanced to clinical trials to determine its efficacy in inflammatory diseases. The pharmacokinetics and pharmacodynamics of CP-105,696 were investigated in healthy male volunteers following oral administration of single doses of 5 to 640 mg.

METHODS

Forty-eight subjects participated in a randomized, double-blind, parallel group study. Plasma and urine concentrations of CP-105,696 were determined at intervals after drug administration. As an indication of LTB4 receptor antagonism following oral administration of CP-105,696, the inhibiton of LTB4-induced upregulation of the neutrophil cell surface complement receptor (CR3), CD11b/CD18, was monitored at 4 h following drug administration using an ex vivo whole blood flow cytometry assay.

RESULTS

Cmax and AUC(0, infinity) increased in a dose-related manner. Respective mean Cmax values were 0.54 to 30.41 microg ml(-1) following doses of 5 to 640 mg. Respective mean AUC(0, infinity) values were 1337 to 16819 microg ml(-1) h for the 40 to 640 mg dose groups. Plasma concentrations declined in a monoexponential manner, with terminal elimination half-lives ranging from 289 to 495 h. Group mean terminal elimination half-lives were dose-independent. Urinary excretion of unchanged drug accounted for < 1% of the administered dose. A linear relationship was observed between CP-105,696 plasma concentrations and inhibition of LTB4-mediated CD11b upregulation on human neutrophils in whole blood. CP-105,696 plasma concentrations of 5-6 microg ml(-1) were necessary to elicit a two-fold shift to the right of the LTB4 concentration response curve for CD11b upregulation.

CONCLUSIONS

These studies demonstrate pharmacologically significant LTB4-receptor antagonism following a single dose of CP-105,696 and pharmacokinetics consistent with once-daily dosing.

The effect of timing of a standard meal on the pharmacokinetics and pharmacodynamics of the novel atypical antipsychotic agent ziprasidone

STUDY OBJECTIVE

To evaluate the influence of a high-fat meal on the pharmacokinetics and pharmacodynamics of the novel atypical antipsychotic drug ziprasidone.

DESIGN

Open, randomized, three-way crossover study.

SETTING

University-based research facility.

SUBJECTS

Eight healthy male volunteers.

INTERVENTIONS

Ziprasidone 20 mg was administered under fasting conditions (treatment A), and directly after (treatment B) and 2 hours after (treatment C) a standard high-fat breakfast.

MEASUREMENTS AND MAIN RESULTS

Serial blood samples were obtained over 36 hours. Three objective psychometric tests were employed to evaluate daytime vigilance at baseline and 2 hours after each dose. Ziprasidone had a significant effect on area under the curve (AUC0-infinity), maximum serum concentration, and half-life (analysis of variance all p<0.05), with the mean AUC0-infinity being significantly greater (627.2 +/- 206.4 vs 371.0 +/- 126.5 ng x hr/ml, ANOVA with Bonferroni's criteria p<0.016) and half-life significantly shorter (4.7 +/- 0.8 vs 6.6 +/- 1.3 hrs, ANOVA with Bonferroni's criteria p<0.016) after treatment B compared with treatment A. Although similar trends were observed after treatment C compared with treatment A, the differences did not reach statistical significance when Bonferroni's correction criteria were applied (p>0.016).

CONCLUSION

These data suggest an increase in systemic exposure to the highly lipophilic compound ziprasidone when taken after fatty foods, possibly due to improved drug dissolution and solubilization. The drug's longer half-life under fasting conditions may reflect dissolution-limited absorption, although this could not be directly assessed. Despite postprandial increases in ziprasidone AUC0-infinity and maximum concentration, daytime vigilance was not affected.

Pharmacokinetics of sertraline and its N-demethyl metabolite in elderly and young male and female volunteers

A nonblinded study was conducted to compare the pharmacokinetic properties of the selective serotonin reuptake inhibitor sertraline in 22 young (aged 18 to 45 years) and 22 elderly (> 65 years) volunteers, of whom half were male and half were female. In this study, sertraline was administered at a dosage of 200mg once daily (the maximum recommended daily dosage) for 21 days after upward dosage titration from 50 mg/day over a 9-day period. Thus, this study was designed to measure the effect of age and gender on the pharmacokinetic properties of sertraline at the maximum dosage recommended for clinical use. The terminal elimination half-life (t1/2 beta ) of sertraline was similar in young females, elderly males and elderly females (mean t1/2 beta ranged from 32.1 to 36.7 hours in these groups) but shorter (22.4 hours) in the young males. The mean maximum plasma sertraline concentration (Cmax) and the mean steady-state area under the plasma concentration-time curve from time zero to 24 hours postdose (AUC24) were also similar between the young females, elderly males and elderly females, but were approximately 25% lower in the young males. The time to Cmax was unaffected by age or gender and ranged from 6.4 to 6.9 hours. N-Demethylsertraline is the principal metabolite of sertraline and does not contribute significantly to its serotonergic actions. The mean values for N-demethylsertraline trough plasma concentrations, AUC24 and Cmax were comparable in elderly males and females and young females but lower in young males. The ratios of mean AUC24 and Cmax for N-demethylsertraline to the AUC24 and Cmax for sertraline were similar between the 4 groups.

A study of the potential effect of sertraline on the pharmacokinetics and protein binding of tolbutamide

The effect of the selective serotonin reuptake inhibitor (SSRI) sertraline 200 mg/day on the metabolism of intravenously administered tolbutamide was examined in a randomised nonblinded parallel-group study in 25 healthy male volunteers. There was a small but statistically significant decrease (16%) in the clearance of tolbutamide in patients receiving the maximum recommended dosage of sertraline. The terminal elimination rate constant was also significantly reduced, corresponding to the increase in the terminal elimination half-life (from 6.9 to 8.6 hours). The decrease in clearance was not associated with any significant changes in plasma protein binding or in the apparent volume of distribution of tolbutamide. This suggests that the change in tolbutamide clearance may be due to a slight inhibition of the cytochrome P450 (CYP) isoenzyme CYP2C9/10 when sertraline was administered in its maximum recommended dosage. However, the small changes in the volume of distribution and plasma binding of tolbutamide after sertraline treatment indicate that there is a minimal interaction between sertraline and tolbutamide.

Effect of sertraline on protein binding of warfarin

The effect of sertraline on the plasma protein binding of warfarin was investigated in a nonblinded randomised placebo-controlled parallel trial in 12 healthy male volunteers. The study participants received single doses of warfarin before administration of sertraline or placebo and again after sertraline or placebo had been administered for 22 days. Treatment with sertraline for 26 days increased the area under the mean prothrombin time vs time curve by 145 sec *h (7.9%), compared with a decrease of 17 sec *h (-1.0%) in the placebo group. Although statistically significant (p = 0.02), this difference was not felt to be clinically meaningful. There appeared to be a slight delay in the normalisation of the prothrombin time in the sertraline-treated group after the second dose of warfarin, which also would not be expected to be clinically significant. After 22 days, a statistically significant (p = 0.02) increase in unbound warfarin was observed in the sertraline group compared with the placebo-treated individuals. Neither the change in prothrombin time nor the change in plasma protein binding were considered to have any clinical relevance; however, good clinical practice dictates that prothrombin time should be monitored in patients treated concurrently with warfarin and sertraline to ensure that the integrity of coagulation response is maintained. The metabolism of warfarin is principally mediated by the cytochrome P450 (CYP) isoenzyme CYP2C9/10. Thus, sertraline appears to have a minimal effect on the CYP2C9/10 isoenzyme.

Sertraline. Chronopharmacokinetics and the effect of coadministration with food

Two nonblinded single-dose randomised 3-way crossover studies were conducted in healthy male volunteers to determine the effect of the time of administration (morning vs evening) and the effect of food on the pharmacokinetics of sertraline tablets. There were no significant treatment effects on the mean area under the plasma concentration-time curve (AUC), mean peak plasma sertraline concentration (Cmax), mean time to reach Cmax (tmax), mean terminal elimination half-life, or the mean elimination rate constant in either study. The results of these 2 studies show that the bioavailability and elimination of sertraline tablets are not influenced by the time of administration or administration with or without food. Thus, sertraline tablets offer the flexibility of morning or evening administration, to patients in the fasting or nonfasting state.

Effect of sertraline on the pharmacokinetics and protein binding of diazepam in healthy volunteers

A double-blind randomised placebo-controlled study was conducted in healthy male volunteers to determine the effects of sertraline on the pharmacokinetics of diazepam and its primary metabolite, N-demethyldiazepam. The effect of sertraline on the plasma protein binding of diazepam was also studied. Sertraline 50 mg/day titrated over a 10-day period to 200 mg/day or placebo was administered for 32 days. A single intravenous dose of diazepam 10 mg was given before the start, and after 21 days of sertraline or placebo treatment. The pharmacokinetic analyses were based on data from 20 individuals. The systemic clearance of diazepam decreased by 32% (-0.100 ml/min/kg) in the sertraline group compared with a 19% decrease (-0.054 ml/min/kg) in the placebo group (p = 0.0266). However, this small difference (13%) between the 2 groups was not considered meaningful. Other than a prolonged time to maximum plasma concentration for N-demethyldiazepam, no other pharmacokinetic parameters were significantly altered by sertraline. The plasma protein binding of diazepam was unchanged by concomitant administration of sertraline. These results suggest that sertraline at the maximum recommended dosage under steady-state conditions, and demethylsertraline, the principal metabolite of sertraline, are unlikely to exert significant inhibitory effects on the CYP2C19 and CYP3A3/4 hepatic isoenzymes responsible for the metabolism of diazepam. Therefore, it would be expected that sertraline would, similarly, have a minimal effect on the pharmacokinetic profile of other drugs metabolised by these hepatic isoenzymes.

Sertraline does not alter the beta-adrenergic blocking activity of atenolol in healthy male volunteers

A double-blind, placebo-controlled, randomized, crossover study was conducted to determine the effect of sertraline on the beta-adrenergic blocking activity of atenolol in 10 healthy male volunteers.

METHOD

To assess the existence of any possible pharmacodynamic interaction between sertraline and atenolol, the effect of sertraline and placebo on the dose of intravenous isoproterenol required to increase heart rate by 25 beats per minute (bpm; chronotropic dose25 [CD25]) and the change in heart rate during exercise in atenolol-treated subjects were determined.

RESULTS

The mean CD25 of isoproterenol was 2.00 micrograms after administration of placebo plus atenolol 50 mg and 2.03 micrograms after administration of sertralnie 100 micrograms plus atenolol 50 mg. The mean heart rate during exercise testing decreased by 29 bpm after sertraline plus atenolol administration and by 31 bpm after placebo plus atenolol administration. Analysis of variance indicated no statistically significant treatment or sequence effects. Only 1 subject experienced an adverse event--a mild headache after administration of sertraline plus atenolol. No clinically significant electrocardiograph changes were observed after sertraline or placebo administration.

CONCLUSION

The results of this study demonstrate that sertraline does not alter the beta-blocking activity of atenolol.

Pharmacokinetics of fluconazole in renal failure

Fluconazole (FLU) is a widely used antifungal agent. The multiple-dose pharmacokinetics of FLU in renal impairment have not been previously investigated. The following groups were studied: volunteers with creatinine clearances (CLcr, > 50 mL/min) of 107 mL/min, given a loading dose of 400 mg and a daily dose of 200 mg/day for 9 days (Group 1); subjects with CLcr between 21 and 50 mL/min with a mean of 38 mL/min, given a loading dose of 200 mg and a maintenance dose of 100 mg/day for 9 days (Group 2); subjects with CLcr between 11 and 20 mL/min with a mean of 14.8 ml/min, given a loading dose of 100 mg and a maintenance dose of 50 mg/day for 9 days (Group 3); and subjects on hemodialysis (three times per week) receiving a loading dose of 200 mg and then 100 mg after each of four dialysis sessions (Group 4) (N = 10 per group). After the administration of the loading dose on Day 1, the mean area under the curve (AUC) (0-24) measurements were approximately proportional to the dose of FLU and independent of renal function. After 10 days of FLU dosing, the mean renal clearance of FLU decreased as CLcr decreased for Groups 1 to 3, and the Day 10 mean half-lives were inversely related to mean CLcr (36.7 h in Group 1, 84.5 h in Group 2, and 101.9 h in Group 3). The mean AUC (0-24) on Day 10 was similar for Group 1 compared with Group 2, despite a reduction in the maintenance dose by 50%. (ABSTRACT TRUNCATED AT 250 WORDS)

Cimetidine does not alter the clearance or plasma binding of tenidap in healthy male volunteers

1. An open-label, placebo-controlled study was conducted to examine the effect of cimetidine on the steady-state pharmacokinetics of tenidap. 2. Twenty-four healthy volunteers received tenidap sodium (120 mg) each morning throughout the study. On day 14 plasma levels of tenidap had reached steady state; half of the subjects were treated concomitantly with cimetidine 800 mg at night, while the other half received placebo. Allocation of cimetidine or placebo was randomised. Plasma profiles of tenidap were measured on days 14 and 16. 3. The addition of cimetidine did not significantly affect the Cmax, tmax, or lambda z of tenidap. The AUC(0,24h) increased by 4% between days 14 and 16 in the cimetidine treatment group, compared with a decrease of 2% in the placebo group. This small difference is statistically significant (P = 0.047), but it is not considered to be clinically relevant. 4. It is concluded that concomitant administration of cimetidine does not significantly affect the pharmacokinetics of tenidap at steady state.

Tenidap sodium does not alter the clearance or plasma protein binding of tolbutamide in healthy male volunteers

1. This randomised, double-blind, parallel group study in 12 healthy young men compared the effects of tenidap sodium 120 mg day-1, at steady state, with placebo on the plasma protein binding and clearance of tolbutamide. 2. Each subject received a 1000 mg intravenous infusion of tolbutamide given over 5 min on day 1 of the study, and again on day 30 following 22 days of successive tenidap or placebo administration. 3. The percentage of unbound tolbutamide in plasma was determined immediately before each infusion. Mean pharmacokinetic parameters (system plasma clearance, terminal phase rate constant, apparent volume of distribution at steady state) of tolbutamide were derived from individual tolbutamide plasma concentration-time curves generated after infusion. The within group day 30 minus day 1 differences were compared between treatment groups. 4. Tenidap was shown to have no statistically or clinically significant effects on any of the parameters assessed. These results indicate that tenidap does not induce or inhibit the P450IIC9 isozyme which metabolises tolbutamide and that tenidap does not displace tolbutamide from plasma protein binding sites. 5. Both tenidap and tolbutamide were well tolerated. No severe treatment-related adverse events were reported, no subject withdrew from the study, and there were no reports of treatment-related laboratory abnormalities, or significant variations in vital signs.

Tenidap sodium decreases renal clearance and increases steady-state concentrations of lithium in healthy volunteers

1. An open-label, randomised placebo-controlled study was conducted to determine the effects of tenidap sodium, a novel, cytokine-modulating anti-rheumatic drug, on the steady-state concentrations and renal clearance of lithium carbonate. 2. Eighteen healthy male volunteers received 450 mg lithium carbonate twice daily for 15 days and once on day 16. On days 9-16 subjects also received either placebo or 120 mg day-1 tenidap 2 h prior to the morning dose of lithium. 3. Following a single dose of tenidap, the renal clearance of lithium decreased significantly by 0.36 l h-1 (-23%) compared with the clearance in the placebo group, which increased by 0.18 l h-1 (+14%). Steady-state serum lithium levels increased after a single dose of tenidap by 0.069 mEq l-1 (+13%), and in the placebo group levels increased by 0.003 mEq l-1 (+0.5%); this difference was not significant. 4. After 7 days' continuous administration of tenidap, the renal clearance of lithium had decreased by 0.38 l h-1 (-25%), compared with the placebo group in which clearance had increased by 0.16 l h-1 (+12%). The steady-state serum concentration of lithium increased by 0.208 mEq l-1 (+39%) in the tenidap group and by 0.063 mEq l-1 (+10%) in the placebo group. Both of these differences were significant. 5. Two subjects who received lithium plus tenidap experienced gastrointestinal side effects, compared with none of those who were administered lithium plus placebo. 6. It is recommended that serum lithium levels be monitored when tenidap and lithium are administered concomitantly.

Effect of tenidap sodium on the pharmacodynamics and plasma protein binding of warfarin in healthy volunteers

1. An open-label, randomised study was performed to assess the effect of tenidap sodium on the pharmacodynamics and plasma protein binding of warfarin. 2. Fourteen healthy male volunteers received either a single oral dose of 120 mg tenidap sodium or matching placebo capsules from days 11 to 36. A single oral dose of 0.75 mg kg-1 warfarin was administered on days 1 and 32. 3. The mean prothrombin AUC(1,120h) value between baseline and day 32 increased from 1692.4 +/- 234.5 s h to 1769.3 +/- 218.0 s h in the group given tenidap, and decreased from 1747.6 +/- 289.4 s h to 1708.1 +/- 236.8 s h in the placebo group. 4. Tenidap caused a slight delay in the normalisation of prothrombin times following the second dose of warfarin on day 32 compared with the first dose on day 1. This was significant at 36, 48, 72 and 96 h but not at 120 h after administration of warfarin. 5. The mean percentage of unbound warfarin in the tenidap group (0.08% +/- 0.09) was significantly different (P = 0.047) from that in the placebo group (-0.03% +/- 0.10) but this was not considered to be clinically meaningful. 6. These data indicate that prothrombin times should be monitored during concomitant administration of tenidap and warfarin.

The effect of tenidap sodium on the disposition and plasma protein binding of phenytoin in healthy male volunteers

1. The effects of tenidap sodium 120 mg day-1 at steady state and placebo on the plasma protein binding and pharmacokinetics of phenytoin were compared in this randomised, double-blind, placebo-controlled, parallel-group study, involving 12 healthy young men, conducted over 34 days. 2. Single oral doses of phenytoin 200 mg were given on days 1-3 and 29-31, and intravenous phenytoin, 250 mg infused over 20 min, was given on days 4 and 32. Tenidap (120 mg day-1), or matching placebo, was administered as single oral daily doses from days 8 to 34 inclusive. 3. The plasma protein binding of phenytoin was determined immediately before oral phenytoin administration on days 1 and 29. Pharmacokinetic parameters were estimated from the serum phenytoin concentration-time curves derived on days 4 and 32 following the phenytoin infusions. The differences between the pre- and post-treatment mean percentage of unbound plasma phenytoin and mean pharmacokinetic parameters were compared between treatment groups. 4. Tenidap sodium 120 mg day-1, at steady state, increased the percentage of unbound phenytoin in plasma by approximately 25%, but did not significantly affect AUC(0,48h) or Cmax. 5. Since tenidap increases the percentage of unbound phenytoin in plasma, when monitoring phenytoin plasma concentrations free concentrations of phenytoin should be considered. 6. Tenidap was well tolerated throughout the study.

Single and multiple dose pharmacokinetics of tenidap sodium in healthy subjects

1. The absorption, protein binding, clearance and absolute bioavailability of tenidap sodium were studied after single and multiple dosing. 2. Thirteen healthy male volunteers received a single 120 mg oral dose of tenidap sodium and a 20 mg intravenous infusion of deuterated tenidap ([D3]-tenidap) on day 1. This was followed by a 6-day washout period (days 2-7) and then further daily doses of oral tenidap sodium 120 mg for 21 consecutive days (days 8-28) with an additional 20 mg intravenous infusion of [D3]-tenidap on day 28. Twelve subjects were eligible for pharmacokinetic evaluation. 3. Following multiple oral doses, the half-life of tenidap is approximately 23 h. 4. Following single and multiple dose administration, the absolute bioavailability is 85%. 5. Systemic clearance of [D3]-tenidap was 29% greater on day 28 than on day 1 indicating a significant increase in intrinsic clearance (CLint) of tenidap since protein binding of tenidap in plasma did not change during the study. Consistent with the increase in systemic clearance, the half-life of [D3]-tenidap decreased and the ratio of AUC(0,24h) day 28/AUC day 1 following oral dosing was less than one. Tenidap is subject to extensive hepatic metabolism, so the increase in CLint may indicate that tenidap induces its own metabolism. 6. Steady-state was achieved by the eleventh day of dosing. Since numerous studies in patients with rheumatoid arthritis have shown that multiple dosing with tenidap is clinically efficacious, this suggests that the pharmacokinetic differences observed between the first and twenty-first day of multiple tenidap dosing do not influence the clinical response.

Sertraline does not alter steady-state concentrations or renal clearance of lithium in healthy volunteers

An open-label, placebo-controlled study was conducted to determine the effects of sertraline on the steady-state levels and renal clearance of lithium in 20 healthy volunteers. Subjects received 600 mg of lithium twice daily for 9 days. On the evening of day 8, subjects received orally either placebo or 100 mg of sertraline; these were administered twice, 8 hours apart, beginning 2 hours after the evening dose of lithium. In a comparison of day 8 with day 9 (before administration of the morning doses of lithium), sertraline was associated with only a 0.01 mEq/L (1.4%) decrease in steady-state levels and a 0.11 L/hour (6.9%) increase in the renal clearance of lithium. Neither change was statistically significant relative to placebo. Four subjects were excluded from analysis because of protocol violations or laboratory abnormalities unrelated to sertraline. Seven subjects who received lithium plus sertraline experienced side effects, mainly tremors, possibly related to treatment, whereas none of those administered lithium plus placebo experienced side effects. No sertraline-related laboratory abnormalities were observed.

Effect of the anti-inflammatory agent tenidap on the pharmacokinetics and pharmacodynamics of prednisolone

The effect of tenidap, a new nonsteroidal anti-inflammatory agent, on the pharmacokinetics and pharmacodynamics of prednisolone was studied in healthy male subjects. In a randomized crossover study, 12 subjects received either tenidap sodium 120 mg daily or placebo orally for 28 days. On day 21, each subject received a single dose of either 0.8 mg/kg oral prednisone or 0.66 mg/kg intravenous prednisolone followed by the other steroid on day 28. Blood and urine samples were collected, and the pharmacokinetic parameters of prednisone and prednisolone were determined in each treatment period. Pretreatment with tenidap did not cause any significant changes in the overall disposition of prednisone or prednisolone. For example, for free prednisolone, the intravenous area under concentration was 1,144 +/- 195 ng.h/mL and 1,244 +/- 140 ng.h/mL, and the systemic availability after oral prednisone was 53 +/- 10% and 51 +/- 12% with placebo and tenidap, respectively. The renal clearance of prednisolone was significantly reduced after tenidap pretreatment, however (from 143 to 77 mL/min/1.73 m2). The suppression of plasma cortisol and whole blood histamine levels were analyzed to evaluate the potential pharmacodynamic interactions between tenidap and prednisolone. There were no significant changes in the pharmacodynamic parameters between placebo and tenidap groups. The excretion of less than 20% of the dose of prednisolone in urine makes the overall effects of tenidap on prednisolone kinetics and dynamics of inconsequential clinical importance.

Drug interactions with fluconazole

Fluconazole, a water-soluble bis-triazole antifungal agent that effectively penetrates the cerebrospinal fluid, is a highly selective inhibitor of the fungal cytochrome P450 system. In single-dose studies, coadministration of cimetidine and fluconazole (100 mg) resulted in an insignificant decrease in the absorption of fluconazole. The coadministration of rifampin and fluconazole (200 mg) decreased both the half-life and the area under the plasma concentration-time curve (AUC) of fluconazole. In multiple-dose studies, fluconazole (50 mg) did not significantly alter the pharmacokinetics of the two steroid components of an oral contraceptive. Coadministration of tolbutamide with fluconazole (100 mg) increased both the maximal plasma concentration and the AUC of tolbutamide without changing levels of blood glucose. The coadministration of cyclosporin A with a low dose of fluconazole (100 mg) was not associated with significant changes in the minimal and the maximal plasma concentrations of cyclosporin A. While higher doses of fluconazole (200 mg) did not affect endogenous steroids, coadministration resulted in changes in the pharmacodynamics of warfarin and the pharmacokinetics of phenytoin and cyclosporin A.

Atrial natriuretic factor in renal failure and posthemodialytic postural hypotension

Atrial natriuretic factor (ANF) levels were ten times normal in hemodialysis patients before dialysis. ANF was not cleared by the dialyzer membrane but plasma levels decreased 47% by the end of dialysis. Patients undergoing peritoneal dialysis had plasma ANF levels four times normal and had detectable ANF in their dialysate. Hemodialysis patients with a marked fall in BP after dialysis had higher ANF levels (P less than 0.05) and lower norepinephrine (NE) levels (P less than 0.05) associated with a failure to increase NE in response to dialysis. Elevated ANF levels are associated with postdialysis hypotension in hemodialysis patients.

The effect of hemorrhage and resuscitation on serum levels of immunoreactive atrial natriuretic factor

To determine if atrial natriuretic factor (ANF) might have a role in blood volume regulation during hypovolemia, the serum level was measured before and after hemorrhage and resuscitation (RESUS) in a porcine shock model. Hemorrhage of 40% of the blood volume produced significant (p less than 0.01) decreases in mean arterial pressure, central venous pressure, and cardiac output and a significant increase in heart rate (HR), plasma renin activity, and catecholamines (p less than 0.01). Hemorrhage was also associated with a significant increase in ANF (p less than 0.05). All parameters except HR returned to baseline values with RESUS. The rise in ANF associated with moderate hemorrhage was unexpected, but may have been due to the profound tachycardia or decreased degradation during shock. Sodium excretion and urine flow increased significantly with RESUS without an associated increase in ANF, suggesting that ANF may not be involved in the early phase of postresuscitation diuresis.

Atrial natriuretic factor in hypovolemic tachycardia

Atrial natriuretic factor (ANF) is released in response to many stimuli which increase right atrial pressure. Following hemorrhage pigs lowered their atrial pressures, developed a tachycardia and increased ANF levels. Electrical pacing increased heart rate and ANF levels. There is a stimulus to ANF release other than atrial stretch, probably heart rate.

Effects of alpha 1 inhibition on renal blood flow and sympathetic nervous activity in systemic hypertension

Doxazosin is a competitive inhibitor of norepinephrine at alpha 1 adrenoceptors on vascular smooth muscle, where it blocks vasoconstriction. Twenty-four patients with mild hypertension were treated with either doxazosin or placebo for 6 weeks. Supine and upright mean arterial pressures decreased by 9 and 12 mm Hg, respectively, in patients receiving doxazosin. This decrease was significantly more than the blood pressure change with placebo (p less than 0.05). Doxazosin therapy led to a small increase in weight (p less than 0.05). It was also associated with a statistically insignificant decrease in renal vascular resistance (568 dynes s/cm5) so that renal blood flow and creatinine clearance did not change. Doxazosin increased renin levels acutely and norepinephrine levels with 6-week treatment, but these changes were not significantly different from placebo. Norepinephrine clearance, measured after a 120-minute infusion of 3H norepinephrine, did not change. Heart rate increased acutely after doxazosin administration, but returned to baseline during 6-week therapy. Blood pressure, measured hourly for 14 hours after treatment, was consistently decreased in all patients. Doxazosin taken once daily lowers blood pressure without affecting renal blood flow or heart rate.

Sympathetic nervous withdrawal in the vasodepressor (vasovagal) reaction

When 40 subjects had 134 ml of blood drawn, 8 of them developed hypotension. These 8 subjects were younger, and when they stood they decreased their systemic arterial pressure, pulse rate and plasma norepinephrine. In contrast, normal subjects increased all these parameters after standing. The fall in plasma norepinephrine suggests a generalized withdrawal of sympathetic nervous tone during vasodepressor reactions. Three subjects maintained a heart rate above 60, but still developed hypotension. Withdrawal of sympathetic tone to the vasculature appears more important than increased vagal tone to the heart in causing hypotension in this reaction.