A dose-response study to assess the renal hemodynamic, vascular, and hormonal effects of eprosartan, an angiotensin II AT1-receptor antagonist, in sodium-replete healthy men

STUDY DESIGN

The effects of orally administered eprosartan on changes induced by angiotensin II in blood pressure, renal hemodynamics, and aldosterone secretion were evaluated in healthy men in this double-blind, randomized, single-dose, placebo-controlled crossover study, which was conducted in three parts. Part 1 (n = 12) assessed the onset and duration of the effect of eprosartan 350 mg or placebo; part 2 (n = 14) assessed the dose-response profile of placebo or 10, 30, 50, 70, 100 or 200 mg eprosartan; and part 3 (n = 5) assessed the duration of the effect of 50, 100, or 350 mg eprosartan.

RESULTS

In part 1 of the study; 350 mg eprosartan caused complete inhibition of angiotensin II-induced pressor and renal blood flow hemodynamic effects (effects on effective renal plasma flow [ERPF]) and inhibited angiotensin II-induced stimulation of aldosterone secretion from 1 to 3 hours after administration. Eprosartan, 350 mg, inhibited the effects of exogenous angiotensin II by approximately 50% to 70% from 12 to 15 hours after dosing. Eprosartan had no angiotensin II agonistic activity and produced an increase in ERPF starting at 1 to 4 hours after dosing. In study part 2, at 3 hours after single doses of 10, 30, 50, 70, 100, and 200 mg, eprosartan inhibited angiotensin 11-induced decreases in ERPF by 39.1%, 49.9%, 33.0%, 56.0%, 71.0%, and 85.7%, respectively, compared with placebo. In study part 3, 50, 100, and 350 mg eprosartan produced measurable Inhibition of angiotensin II-induced decreases in ERPF from 12 to 15 hours after administration. In parts 2 and 3, the eprosartan angiotensin II antagonism on blood pressure response and aldosterone secretion mirrored the angiotensin II antagonism on ERPF.

Effect of ranitidine on the pharmacokinetics of orally administered eprosartan, an angiotensin II antagonist, in healthy male volunteers

OBJECTIVE

To assess the effect of ranitidine on the pharmacokinetics of eprosartan in healthy male volunteers.

DESIGN

Single-center, randomized, open-label, two-period, period-balanced, crossover study.

PATIENTS

Seventeen healthy men aged 19 to 43 years.

INTERVENTION

In each period (separated by a > or = 7 d washout), subjects received a single 400-mg oral dose of eprosartan alone, or a single oral dose of eprosartan 400 mg and ranitidine 150 mg on day 4 after 3 days of ranitidine 150 mg twice daily. Serial pharmacokinetic samples were obtained for up to 24 hours following eprosartan dosing.

MAIN OUTCOME MEASURES

Plasma and urine eprosartan concentrations during each treatment session.

RESULTS

Eprosartan maximum concentration (Cmax), the AUC from time-zero to the last quantifiable concentration (AUC0-t), and renal clearance (Cl(r)) values were approximately 7%, 11%, and 4% lower, respectively, when administered with ranitidine compared with eprosartan alone. The 95% CIs for the ratio of eprosartan plus ranitidine compared with eprosartan alone were 0.81 to 1.07, 0.77 to 1.03, and 0.64 to 1.43, for Cmax, AUC0-t, and Cl(r), respectively, indicating no statistically significant difference between regimens.

CONCLUSIONS

Repeated doses of ranitidine did not have a marked effect on the single-dose pharmacokinetics of eprosartan.

Pharmacokinetics and protein binding of eprosartan in healthy volunteers and in patients with varying degrees of renal impairment

This was an open-label, parallel group study to compare the pharmacokinetics of multiple oral doses of eprosartan in subjects with normal renal function (Clcr > 80 mL/min; n = 8) and patients with mild (Clcr 60-80 mL/min; n = 8), moderate (Clcr 30-59 mL/min; n = 15), or severe (Clcr < 30 mL/min; n = 3) renal insufficiency. Each subject received oral eprosartan 200 mg twice daily for 6 days and a single dose on day 7. Mean total maximum concentration (Cmax) and area under the concentration-time curve from 0 to 12 hours (AUC0-12) were similar for healthy subjects and those with mild renal impairment, but were an average of 25% to 35% and 51% to 55% greater for patients with moderate and severe renal impairment, respectively, compared with healthy subjects. Mean renal clearance (Clr), which was similar for healthy subjects and patients with mild renal impairment, was decreased an average of 41% and 95% in the groups with moderate and severe renal impairment, respectively, compared with normal subjects. Eprosartan was highly bound to plasma proteins in all groups; however, the unbound fraction was increased approximately two-fold in the group with severe renal impairment. Mean unbound Cmax and AUC0-12 were an average of 53% to 61% and 185% to 210% greater for the patients with moderate and severe renal impairment, respectively, compared with healthy subjects. Headache was the most common adverse experience reported in all subgroups. Eprosartan was safe and well tolerated regardless of degree of renal impairment. Cmax and AUC were increased and renal clearance decreased in patients with moderate to severe renal impairment in comparison to healthy subjects and patients with mild renal impairment. However, based on the moderate renal clearance and known safety profile of eprosartan, it is not necessary to adjust the dose of eprosartan in patients with renal insufficiency.

A dose proportionality study of eprosartan in healthy male volunteers

The present study investigated the proportionality of exposure after single oral doses of 100, 200, 400, and 800 mg of eprosartan, a nonpeptide, nonbiphenyl angiotensin II receptor antagonist, in 23 healthy young men. Eprosartan was safe and well tolerated. Exposure to eprosartan increased with dose but in a less than proportional manner. For each two-fold dose increase, area under the concentration--time curve (AUC) increased an average of 1.6 to 1.8 times and maximum plasma drug concentration (Cmax) increased an average of 1.5 to 1.8 times. For both parameters, the greatest difference from the dose multiple was observed between the 400- and 800-mg doses. Dose proportionality of eprosartan, as assessed by an equivalence-type approach using the 100-mg dose as the reference and a 30% acceptance region (0.70, 1.43), was achieved for the 200- and 400-mg doses for AUC and the 200-mg dose for Cmax. The observed changes in the pharmacokinetics of eprosartan suggest slight saturation of absorption of eprosartan over the 100- to 800-mg dose range, most likely due to the physicochemical properties of the drug (pH-dependent aqueous solubility and lipophilicity).

Paroxetine does not affect the cardiac safety and pharmacokinetics of terfenadine in healthy adult men

Potent CYP3A4 inhibitors such as ketoconazole can cause dangerous increases in plasma concentrations of the H-1 antagonist terfenadine. In light of recent reports that the selective serotonin reuptake inhibitor antidepressants may be weak CYP3A4 inhibitors, this study was designed to investigate the effects of paroxetine on the pharmacodynamic and pharmacokinetic profile of terfenadine. Twelve healthy male volunteers participated in a randomized open-label, two-period, steady-state crossover study. Terfenadine (60 mg twice daily for 8 days) was administered alone and with paroxetine at steady state (20 mg once daily for 15 days, with terfenadine on days 8 through 15). Extensive electrocardiogram monitoring was conducted throughout, and terfenadine and carboxyterfenadine pharmacokinetics were assessed at the end of each treatment period. One subject withdrew because of adverse experiences related to paroxetine, but the other 11 subjects completed the study uneventfully. On the final day of coadministration, the rate-corrected QT interval (QTc) was unaltered compared with terfenadine dosed alone; maximum QTc values (mean [SEM]) were 404 (4) and 405 (5) msec, respectively. Terfenadine pharmacokinetics were also unchanged; geometric mean steady-state area under the curve (AUC)tau values were 30.0 ng.hr/mL during coadministration compared with 30.8 ng.hr/mL when dosed alone (p > 0.05). The corresponding Cmax values were 3.68 and 3.64 ng/mL (p > 0.05). There was, however, a small (on average 17-20%), unexplained reduction in the steadystate Cmax and AUCtau of carboxyterfenadine during coadministration with paroxetine. In conclusion, paroxetine does not affect the pharmacokinetics or cardiovascular effects of terfenadine. The small reduction in carboxyterfenadine plasma concentrations is unlikely to be important clinically.

Relevance of oral intake and necessity to void as ambulatory surgical discharge criteria

Discharge criteria used in the outpatient setting of a 500-bed academic medical center were evaluated by nursing staff in two ambulatory units to determine validity in identifying patient readiness for discharge. Criteria categories include temperature, circulation, activity and mental status, pain, bleeding, voiding, and oral intake. The hospital course and post-discharge course of a convenience sample of 248 ambulatory subjects was drawn from consecutive patients. Post-discharge recovery outcomes identified by the telephone assessment included recovery, complications, necessity of further medical treatment, and the need to return to a medical facility. The descriptive results showed the safety of the seven discharge criteria. Voiding and oral intake were related to prolonged stays in the ambulatory units. Approval was granted by the Hospital Policy Board to relax discharge criteria, and make voiding and oral intake optional for patients. A stage II follow-up study of 1,582 patient subjects was conducted using the new criteria of voluntary voiding and oral intake. The average ambulatory stay was reduced 50 minutes after voiding and oral intake were made optional.

Effect of fluconazole on the pharmacokinetics of eprosartan and losartan in healthy male volunteers

OBJECTIVE

To investigate the effect of steady-state fluconazole administration on the disposition of eprosartan, losartan, and E-3174.

METHODS

Sixteen healthy male subjects received 300 mg eprosartan every 12 hours, and 16 received 100 mg losartan every 24 hours on study days 1 to 20. All 32 subjects received 200 mg fluconazole every 24 hours beginning on day 11 and continuing through day 20. Serial blood samples were collected over one dosing interval on study days 10 and 20 for measurement of plasma concentrations of eprosartan, losartan, and E-3174 (the active metabolite of losartan).

RESULTS

There was no significant difference in eprosartan area under the concentration-time curve from time 0 to time of last quantifiable concentration [AUC(0-t)] or maximum concentration (Cmax) when administered alone and with fluconazole. After concomitant administration with fluconazole, losartan AUC(0-t) and Cmax were significantly increased 66% and 30%, respectively, compared with those values for losartan alone. The AUC(0-t) and Cmax for E-3174 were significantly decreased 43% and 56%, respectively, after administration of losartan with fluconazole.

CONCLUSIONS

Fluconazole significantly increases the steady-state AUC of losartan and inhibits the formation of the active metabolite of losartan, E-3174. In contrast, fluconazole administration has no effect on the steady-state pharmacokinetics of eprosartan.

Lack of effect of eprosartan on the single dose pharmacokinetics of orally administered digoxin in healthy male volunteers

AIMS

To study the effect of eprosartan, a nonbiphenyl tetrazole angiotensin II receptor antagonist, on digoxin pharmacokinetics in a randomized, open-label, two period, period balanced crossover study in 12 healthy men.

METHODS

Each subject received a single 0.6 mg oral dose of digoxin (Lanoxicaps 0.2 mg/capsule, Glaxo Wellcome) alone or following 4 days of dosing with eprosartan 200 mg orally every 12 h. Each study period was separated by a 14 day washout interval. Serial blood samples were obtained for up to 96 h after each digoxin dose for determination of digoxin pharmacokinetics. The effect of eprosartan on digoxin pharmacokinetics was assessed through an equivalence-type approach using AUC(0, t') as the primary endpoint.

RESULTS

For AUC(0, t'), the ratio of digoxin+eprosartan: digoxin alone was 0.99 with a 90% confidence interval (CI) of [0.90, 1.09]. For Cmax, the ratio was 1.00 with a 90% CI of [0.86, 1.17]. tmax was similar for both regimens. Both regimens were safe and well tolerated.

CONCLUSIONS

Based on AUC and Cmax data, it can be concluded that eprosartan has no effect on the pharmacokinetics of a single oral dose of digoxin.

Eprosartan, an angiotensin II receptor antagonist, does not affect the pharmacodynamics of glyburide in patients with type II diabetes mellitus

The potential for eprosartan, a nonbiphenyl tetrazole angiotensin II receptor antagonist, to affect the 24-hour plasma glucose profiles in type II diabetic patients treated with glyburide was investigated in this randomized, placebo-controlled, double-blind (eprosartan-placebo phase only), two-period, period-balanced, crossover study. All patients received a stable oral dose (3.75-10 mg/day) of glyburide for at least 30 days before the first dose of double-blind study medication was administered. Patients were randomized to receive either 200-mg oral doses of eprosartan twice daily or matching oral placebo doses concomitantly with glyburide for 7 days during each treatment period. After a minimum washout period of 14 days, patients were crossed over to the alternate treatment. Serial samples to measure glucose concentrations in plasma were collected over a 24-hour period on the day before administration of eprosartan or placebo and again on day 7. Mean glucose concentrations were comparable between treatment groups before administration of eprosartan or placebo. The point estimate (90% confidence interval) for the ratio of the average mean 24-hour plasma glucose concentrations of eprosartan + glyburide to placebo + glyburide after 7 days of administration was 0.96 (0.90, 1.01). Eprosartan did not significantly alter the 24-hour plasma glucose profile in patients with type II diabetes mellitus who were previously stabilized on glyburide.

Role of hyperpronation as a possible risk factor for anterior cruciate ligament injuries

OBJECTIVE

The purpose of this study was to examine the relationship between hyperpronation and the occurrence of noncontact injury to the anterior cruciate ligament (ACL).

DESIGN AND SETTING

Subjects were categorized as either ACL injured (ACLI) or ACL uninjured (ACLU). All ACLI subjects received their injuries from a noncontact mechanism. To justify using the ACLI subjects' uninjured legs as representative of their preinjury state, a t test was used to compare the differences between the left and right foot for the ACLU group on both measurements. Based on the results of the t test, a regression analysis was performed to determine whether group membership could be predicted from navicular drop. All measures were performed in a university athletic training room.

SUBJECTS

Fourteen ACLI subjects (age = 21.07 +/- 0.83 yr, ht = 174.81+/-8.29 cm, wt = 72.32+/-13.47 kg) and 14 ACLU subjects (age = 21.14+/-2.03 yr, ht = 177.35+/-11.31 cm, wt = 72.99+/-14.81 kg) participated.

MEASUREMENTS

Hyperpronation was assessed via the navicular drop test and the calcaneal stance test.

RESULTS

No significant difference (p > .05) between feet for the navicular drop test was found. However, there was a significant difference (p < .05) between feet for the calcaneal stance test, and, thus, this measure was not used in the regression analysis. Using the navicular drop score, the regression analysis was unable to predict group membership.

CONCLUSIONS

Hyperpronation as measured by the navicular drop test was not a predictor of ACL injury, and, thus, may not be a predisposing factor to noncontact ACL injuries.

Callus distraction in reconstructive foot surgery

Though by no means a new concept, the science of callus distraction has stimulated significant interest among surgeons over the past several years. As our knowledge and understanding of the principles of this technique have evolved, the clinical indications have been expanded. In this manuscript, we will illustrate several examples of these broadened indications. An innovative alternative to the Evans opening wedge calcaneal osteotomy, which usually requires bone graft or bone graft substitutes, is presented.

Retrospective evaluation of graded stress examination of the ankle

Stress radiography of the ankle commonly is used to evaluate talar tilt in patients with a history of inversion ankle sprains. Manual and instrumented procedures have been variously described in the literature. No reports have documented normative talar tilt as measured using the Telos ankle stress device in a large clinical population. In addition, little has been done to examine the value of using graded displacement forces compared with a single displacement force. Bilateral Telos examinations from 113 consecutive patients taken during a 4-year period were evaluated for this study. No measurable talar tilt was observed in 65.8% of the ankles in this study. Talar tilt ranged from 1.7 degrees to 24.9 degrees in injured ankles. In patients with quantifiable talar tilt, all had greater talar tilt at the 15 kPa force than at all other forces. Because of the variability in talar tilt in injured and comparison ankles, clinical conclusions regarding injury severity cannot be made on measured talar tilt alone. The analysis suggests that inversion stress examination is helpful in documenting gross talar instability, but the discriminant value of the procedure to determine the anatomy and severity of lateral ligament injury is tenuous.

Hot and cold whirlpool treatments and knee joint laxity

OBJECTIVE

To examine the influence of clinical applications of heat and cold on arthrometric laxity measurements of the knee.

DESIGN AND SETTING

The knee joint was submersed 4 inches above the patella in hot and cold whirlpools containing water of 40 degrees C and 15 degrees C for 20 minutes. A control was also performed to provide a neutral temperature comparison group.

SUBJECTS

Eight males and 7 females with no history of knee injury.

MEASUREMENTS

The knee was maintained at 20 degrees flexion and tibial rotation at either 15 degrees of internal rotation, 15 degrees of external rotation, or a neutral measurement with a modified KT-1000 knee arthrometer equipped with an LCCB-50 strain gauge that allowed for the digital display of the applied distraction forces. Order of testing was counterbalanced. Subjects underwent each condition once, with each trial on separate days. Two 2-factor repeated measure analyses of variance were performed to test effects of temperature on knee laxity for the dependent measure (laxity at 89N and at maximal displacement forces).

RESULTS

There was no thermal effect on displacement at 89N nor at maximal distraction (p > .05). A difference was found with respect to test position, with external rotation showing a greater displacement than internal rotation (p < .05).

CONCLUSIONS

There was no evidence that hot or cold whirlpool treatments alter knee laxity as assessed with the KT-1000. Rotation of the tibia does affect the magnitude of displacement of the knee. Further research is needed to determine if these findings can be applied to ACL-deficient or ACL-reconstructed knees.

Alternatives to the closing base wedge osteotomy

The closing base wedge osteotomy remains a viable option in treating hallux valgus deformities with high intermetatarsal angles; however, the procedure can be technically difficult to perform and has been associated with a fair number of potential complications. As a result, a variety of osteotomies have been introduced and modified over the years that may serve as alternatives. Though all procedures possess complications, several of these alternatives do offer some significant advantages over the closing base wedge osteotomy.

Interspecies pharmacokinetics of a novel hematoregulatory peptide (SK&F 107647) in rats, dogs, and oncologic patients

PURPOSE

To study the pharmacokinetics of SK&F 107647, a novel hematoregulatory agent, in rats, dogs, and patients with non-lymphoid solid tumor malignancy.

METHODS

Sprague Dawley rats and beagle dogs (n = 6 each; 3 M, 3 F) were given 25 mg/kg of SK&F 107467 as an iv bolus injection, and patients (n = 6; 4 M, 2 F) received 100 mg/kg as a 2 hour iv infusion. Plasma samples were assayed for drug using either HPLC (rat and dog) or RIA (human).

RESULTS

In each species the plasma clearance (CL) of SK&F 107647 was low in relation to hepatic blood flow, and the volume of distribution (Vd ss) was reflective of distribution to extracellular body water. The plasma CL in humans was near that of average glomerular filtration rate. Using allometric equations for interspecies scaling (Y = a.W(b)), body-weight normalized human pharmacokinetic data were reasonably predicted using either the body weight normalized rat or the dog data. The allometric exponents (b) for CL, Vd(ss), and T(1/2) of SK&F 107647 were 0.63, 0.94, and 0.29, respectively.

CONCLUSIONS

Use of a limited pool of available animal data allowed for reasonable predictions of human pharmacokinetics of SK&F 107647.

Effects of ofloxacin on the pharmacokinetics and pharmacodynamics of procainamide

Procainamide is a class I antiarrhythmic agent that undergoes active tubular secretion through the organic cation transport system, with approximately 50% of a dose excreted in the urine as unchanged drug. The remainder is metabolized to an active metabolite, n-acetyl procainamide (NAPA). Ofloxacin is a fluoroquinolone antibiotic that is excreted in the urine as unchanged drug via active tubular secretion and glomerular filtration. To test the hypothesis that ofloxacin may interfere with the renal elimination of procainamide, 9 healthy volunteers were randomly assigned to receive 1 g of oral procainamide as a single dose with or without pretreatment with 400 mg of ofloxacin twice a day for 5 doses. Blood and urine samples were obtained and pharmacokinetic parameters for procainamide were determined for each treatment period. Standard 12-lead and signal-averaged electrocardiographic recordings were used for pharmacodynamic analysis. The mean area under the concentration-time curve (AUC) and peak plasma concentration (Cmax; mug/mL) for procainamide increased by 27% and 21%, respectively, and the plasma clearance for procainamide decreased by an average of 22% with coadministration of ofloxacin. Ofloxacin did not significantly influence the pharmacokinetics of NAPA, nor were pharmacodynamics of procainamide significantly affected by coadministration of ofloxacin. These results suggest that procainamide concentrations should be monitored closely when coadministered with ofloxacin.

Effect of ACL Reconstruction and Tibial Rotation on Anterior Knee Laxity

The anterior cruciate ligament (ACL) is the primary restraint to anterior translation of the tibia on the femur. Research suggests that resistance to anterior translation changes as the tibia is rotated internally and externally. This study assessed the degree to which ACL reconstruction and tibial rotation affects anterior knee laxity. Nine subjects with ACL lesions and functional instabilities participated in the study. Subjects were measured 1 to 10 days before surgery and 6 to 8 months after ACL reconstruction using the KT-1000 knee arthrometer. A mechanical leg stabilizer was used to assess anterior translation at 20 degrees of knee flexion in three positions: internal rotation of 15 degrees , neutral, and external rotation of 15 degrees . Subjects were measured at 89 and 67 N of anterior force. Data were analyzed with a three-factor (test x position x force) repeated measures ANOVA. Following surgery, reduction in laxity (mm) for the three positions (internal rotation, neutral, and external rotation) was 1.9, 2.8, and 3.4, respectively, at 89 N and 1.5, 2.0, and 2.6, respectively, at 67 N. The degree of reduction in laxity (presurgery to postsurgery) was dependent upon rotation and force, and was greatest in external rotation and least in internal rotation pre- to postsurgery. We concluded that ACL reconstruction using a patellar tendon graft significantly decreased anterior tibial translation at all three positions, but a greater amount of reduction was observed postsurgically at the externally rotated position. This supports the theory that mechanical blocks and secondary restraints such as a taut mid-third of the iliotibial tract may interfere with clinical laxity tests in some positions of tibial rotation. Fixing the tibia in an externally rotated position may decrease the effect of secondary restraints and improve sensitivity in testing for ACL laxity.

Emergency medicine and the underage athlete

Most high school and some collegiate athletes are legal minors. In civil matters, the law treats minors (usually individuals under the age of 18 years) uniquely. Limitations exist on a minor's ability to enter into contracts, make determinations regarding medical care, and bear responsibility for personal actions. Medical professionals are often unclear on matters relating to the provision of medical care to minors. The purpose of this discourse is to present selected legal issues in the context of two fictional case studies. Case 1 presents issues regarding the definition of emergency medical conditions and the related emergency medical doctrine. Case 2 provides an example of an acute medical concern which fails to fall under emergency medical classification but rather provides a context for discussing the mature minor doctrine. Both cases are analyzed in light of these doctrines in addition to other pertinent legal considerations.

Glucose emergencies: recognition and treatment

Millions of Americans have pathologies related to glucose regulation. Many of these individuals have diagnosed diabetes. There are, however, countless others who are unaware that they have glucose regulation disorders. Athletic trainers may find themselves called upon to work with individuals with documented and undocumented disorders. The purpose of this article is to define three primary glucose emergencies (diabetic ketoacidosis, diabetic hyperosmolar state, and hypoglycemia) and discuss the treatment for each. Attention is focused on signs and symptoms which allow the athletic trainer to differentiate between the conditions.

Thiopental as an adjunct to hypothermia for EEG suppression in infants prior to circulatory arrest

Fifteen infants were studied to evaluate the effect of profound hypothermia (16 degrees C to 18 degrees C) and hypothermia plus thiopental on the electroencephalogram (EEG) prior to circulatory arrest. Mean patient age and weight were 5.5 +/- 1.2 months and 4.9 +/- 0.3 kg, respectively. After core cooling on cardiopulmonary bypass (CPB), all patients received thiopental, 8 mg/kg, 5 minutes prior to circulatory arrest. Satisfactory EEG recordings were obtained for 9 patients, and serum thiopental concentration was measured in 12 patients. Hypothermia (mean venous return temperature, 17.8 degrees C +/- 1.6 degrees C) alone was associated with persistent cerebral electrical activity in 8 of 9 patients (89%). The addition of thiopental, 8 mg/kg, produced an isoelectric EEG in 6 of these 8 patients (75%). Mean circulatory arrest duration was 44 +/- 4 minutes. EEG activity resumed after reinstitution of CPB in all patients. Serum thiopental concentration at the end of CPB was negligible. It is concluded that hypothermia alone often may not produce EEG isoelectricity, and that the associated cerebral metabolic activity may be suppressed by adjunctive use of thiopental.

Hemodynamic effects of muscle relaxant drugs during anesthetic induction in patients with mitral or aortic valvular heart disease

The hemodynamic effects of three nondepolarizing skeletal muscle relaxant drug regimens were compared during the induction of general anesthesia in 64 patients with valvular heart disease using a double-blind protocol. Patients were first stratified according to primary valvular defect (aortic stenosis, aortic regurgitation, mitral stenosis, or mitral regurgitation). Next, patients were randomly allocated to a drug group, either group A (atracurium), group V (vecuronium), or group MP (metocurine plus pancuronium). Data were collected during three periods: awake, postanesthetic induction, and posttracheal intubation. Four cardiovascular variables were designated a priori as primary variables of interest. These were heart rate (HR), mean arterial pressure (MAP), cardiac index (CI), and systemic vascular resistance index (SVRI). Patients with mitral stenosis showed two significant hemodynamic differences among muscle relaxant drug groups: (1) CI increased in group A but decreased in group MP between the awake and postinduction measurements (P = 0.032); and (2) SVRI decreased in group A but increased in group MP between the awake and postintubation periods (P = 0.034). In contrast, patients with aortic stenosis, aortic regurgitation, or mitral regurgitation demonstrated no statistically significant difference in cardiovascular responses among drug groups. Further analysis was performed using the following data: (1) other hemodynamic variables; (2) incidence of deviations from cardiovascular stability; and (3) the frequency of cardiovascular drug use. This examination showed no important differences among the muscle relaxant drug groups. The small but significant hemodynamic changes observed in mitral stenosis patients in drug groups A and MP were not noted with vecuronium.(ABSTRACT TRUNCATED AT 250 WORDS)

The onset and duration of neuromuscular blockade using combinations of atracurium and vecuronium

The effect of atracurium-vecuronium combinations on the onset and duration of neuromuscular blockade was investigated in 30 adult patients undergoing general anaesthesia for elective surgery. The patients were randomized to receive either atracurium 0.6 mg.kg-1, vecuronium 0.1 mg.kg-1, or quarter-dose, half-dose, or full-dose combinations of the two drugs. Neuromuscular blockade was assessed by measuring the evoked electromyographic response of the abductor digiti minimi to transcutaneous stimulation of the ulnar nerve. It was found that half-dose combinations of atracurium and vecuronium did not produce a shorter onset time, but did result in a longer duration of neuromuscular blockade than full-doses of either drug alone (P less than 0.01). The quarter-dose combinations did not reduce onset time or increase duration. The full-dose combinations produced both a shorter onset time (P less than 0.01) and a longer duration (P less than 0.001). The results indicate that atracurium-vecuronium combinations are supra-additive in terms of the duration of the neuromuscular blockade produced. However, the inability of atracurium-vecuronium combinations to reduce onset time without increasing duration suggests that there is little advantage in combining the two drugs in clinical practice.

Brachymetatarsia. A new surgical approach

Although most practitioners are familiar with brachymetatarsia, it is a relatively uncommon clinical entity presenting for surgical correction. Traditional methods of surgical correction have been successful for the most part; however, a number of potentially devastating complications exist with these procedures. The authors present a review of the deformity, including the historical surgical techniques, and introduce a new surgical approach that minimizes the risk of complication.