Fenoldopam, a dopamine agonist, for hypertensive emergency: a multicenter randomized trial. Fenoldopam Study Group

Despite successful therapies for chronic hypertension, hospital admissions for hypertensive emergency more than tripled between 1983 and 1992.

OBJECTIVE

To examine the safety and efficacy of fenoldopam, the first antihypertensive with selective and specific action on vascular dopamine (DA1) receptors, in a clinical trial involving emergency department patients with true hypertensive emergencies.

METHODS

Patients with a sustained diastolic blood pressure (DBP) of > or =120 mm Hg and evidence of target organ compromise were randomized in a double-blinded manner to one of four fixed doses of intravenous fenoldopam (0.01, 0.03, 0.1, or 0.3 microg/kg/min) for 24 hours. The primary endpoint was the magnitude of DBP reduction in each of the three higher-dose groups after four hours of fenoldopam treatment compared with the lowest-dose group.

RESULTS

One hundred seven participants from 21 centers were enrolled, and 94 patients received fenoldopam. Evidence of acute target-organ damage included new renal dysfunction or hematuria (50%), acute congestive heart failure or myocardial ischemia (48%), and papilledema or grade III-IV hypertensive retinopathy (34%). The DBP decreased in a dose-dependent fashion, with significant differences between the 0.1- and 0.3-microg/kg/min groups compared with the lowest-dose group. Treatment was well tolerated, and there were no deaths or serious adverse events during follow-up, up to 48 hours. All patients were successfully transitioned to oral or transdermal antihypertensives with maintenance of blood pressure control.

CONCLUSIONS

Fenoldopam safely and effectively lowers blood pressure in a dose-dependent manner in patients with hypertensive emergencies. Observations supporting potential risk factors for hypertensive emergency are discussed.

Ziconotide, a new N-type calcium channel blocker, administered intrathecally for acute postoperative pain

BACKGROUND AND OBJECTIVES

Voltage-sensitive calcium channel conductance is essential for the nervous system to signal a painful event. However, intrathecal administration of L-type calcium channel blockers does not provide analgesia. The present investigation was designed to assess the safety and analgesic efficacy of ziconotide, a new N-type calcium channel blocker, when administered intrathecally to patients with acute postoperative pain.

METHODS

This randomized, double-blind, pilot study included patients undergoing elective total abdominal hysterectomy, radical prostatectomy, or total hip replacement. After intrathecal injection of local anesthetic and before surgical incision, a continuous intrathecal infusion of either placebo or 1 of 2 doses of ziconotide (0.7 microg/h or 7.0 microg/h) was started and continued for 48 to 72 hours postoperatively. Primary and secondary efficacy variables were the mean daily patient controlled analgesia (PCA) morphine equivalent consumption and visual analog pain intensity (VASPI) scores, respectively.

RESULTS

Thirty patients received study drug; 26 were evaluable for efficacy. Mean daily PCA morphine equivalent consumption was less in patients receiving ziconotide than in placebo-treated patients, and the difference was statistically significant between 24 and 48 hours (P = .040). VASPI scores during the first 8 hours postoperatively were markedly lower in ziconotide-treated than in placebo-treated patients. In 4 of 6 patients receiving the high-dose of ziconotide (7 microg/h), adverse events, such as dizziness, blurred vision, nystagmus, and sedation contributed to study drug being discontinued after 24 hours. After ziconotide discontinuation, these symptoms resolved.

CONCLUSIONS

Ziconotide showed analgesic activity, as shown by decreased PCA morphine equivalent consumption and lower VASPI scores. Because of a favorable trend of decreased morphine consumption with an acceptable side-effect profile in the low-dose ziconotide group, 0.7 microg/h may be closer to the ideal dose than 7 microg/h. Large-scale studies are required to clarify this issue.

Effects of an N-type calcium channel antagonist (SNX 111; Ziconotide) on calcium-45 accumulation following fluid-percussion injury

Accumulation of calcium following experimental traumatic brain injury (TBI) has been demonstrated to be a prominent pathophysiological component that can compromise mitochondrial functioning and threaten cell survival. The omega-conopeptide SNX-111, also known as Ziconotide, is a potent antagonist of the voltage-gated N-type calcium channel and has demonstrated significant neuroprotective effects against ischemia-induced neuronal injury. To determine whether this compound would be effective in reducing calcium accumulation associated with TBI, SNX-111 was administered intravenously to rats 1 hour following a moderate (2.2 to 2.75 atm) lateral fluid-percussion injury (or sham) at doses of 1 (n = 30), 3 (n = 31), or 5 (n = 30) mg/kg; another group received 0.9% saline solution (n = 35). Brains were processed for calcium 45 (45Ca) autoradiography at 6, 12, 24, 48, and 96 hours following insult. Optical density measurements of 20 cortical and subcortical regions were analyzed. Injured animals administered saline solution exhibited a significant increase in 45Ca uptake within 12 regions ipsilateral to the site of injury. The most prominent increases were evident throughout the ipsilateral cerebral cortex. SNX-111 reduced the injury-induced calcium accumulation within the ipsilateral cortex in a dose-response fashion when measured at 6, 12, and 48 hours after insult. These drug-induced reductions in calcium accumulation were as high as 75% in the ipsilateral cerebral cortex, and up to 50% in other ipsilateral regions (including thalamus and hippocampus). Consequently, the results suggest that posttraumatic blocking of the voltage-gated N-type calcium channel after injury reduces prolonged, trauma-induced calcium accumulation.

The effects of fenoldopam, a selective dopamine receptor agonist, on systemic and renal hemodynamics in normotensive subjects

OBJECTIVE

Acute renal failure, frequently a consequence of renal vasoconstriction and subsequent renal ischemia, is a common problem for which no proven preventive or therapeutic agents exist. Fenoldopam is a new, selective, dopamine-1 receptor agonist that causes both systemic and renal arteriolar vasodilation. In hypertensive patients, fenoldopam rapidly decreases blood pressure, increases renal blood flow, and maintains or improves the glomerular filtration rate. We sought to determine a dose of fenoldopam that increases renal blood flow without inducing hypotension in normotensive patients and to explore the role of volume status (sodium replete vs. deplete) in these effects.

DESIGN

Randomized, double-blind, placebo-controlled, cross-over study.

SETTING

Clinical research unit.

PATIENTS

Fourteen normal male volunteers.

INTERVENTIONS

Renal plasma flow (para-aminohippurate clearance) and glomerular filtration rate (inulin clearance) were measured during three fixed, escalating doses of fenoldopam (0.03, 0.1, and 0.3 Lg/kg/min) on both a high-sodium and a low-sodium diet.

MEASUREMENTS AND MAIN RESULTS

Fenoldopam significantly increased renal plasma flow in a dose-dependent manner compared with placebo: 670 + 148 vs. 576 + 85 mUmin at 0.03 iLg/kg/min; 777 + 172 vs. 579 + 80 mUmin at 0.1 tig/kg/min; and 784 + 170 vs. 592 + 165 mUmin at 0.3 ilg/kg/min (p < .05 fenoldopam vs. placebo at all three doses). Glomerular filtration rate was maintained. At the lowest dose (i.e., 0.03 ILg/kg/min), significant renal blood flow increases occurred without changes in systemic blood pressure or heart rate. At 0.1 and 0.3 Lgl/kg/ min, systolic blood pressure did not change, but diastolic blood pressure was slightly lower in the fenoldopam group than in the placebo group: 62.5 + 6.4 vs. 63.6 + 2.6 mm Hg, respectively, at 0.3 tg/kg/min (p < .05). None of the effects of fenoldopam were altered by volume status.

CONCLUSIONS

Fenoldopam increased renal blood flow in a dose-dependent manner compared with placebo, and, at the lowest dose, significantly increased renal blood flow occurred without changes in systemic blood pressure or heart rate. These findings will be useful in designing future studies exploring the role of fenoldopam in preventing or treating renal failure in patients who are not hypertensive.

Prolonged fenoldopam infusions in patients with mild to moderate hypertension: pharmacodynamic and pharmacokinetic effects

Thirty-three patients with mild-to-moderate essential hypertension received either placebo or fenoldopam, a selective dopamine-1 agonist, by intravenous infusion at a fixed infusion rate ranging from 0.1 to 0.8 microg/kg/min for 48 h during a double-blind, placebo-controlled, randomized inpatient clinical trial. Blood pressure and heart rate were measured every 15 min for 24 h before, during, and 24 h after the 48-h drug infusion. Plasma concentrations of racemic fenoldopam were measured at frequent intervals during and for 24 h after fenoldopam infusion. In the 26 patients who received fenoldopam, there were dose-dependent reductions in systolic and diastolic blood pressure, which usually reached a nadir within 2 h of beginning infusion and were significant even at the lowest dose studied (-9 and -9 mm Hg for systolic and diastolic blood pressure, respectively, at 24 h for the dose of 0.04 microg/kg/min, P < .05). There were associated increases in heart rate that were greater in the first than in the last 24 h of drug infusion. Compared to the average 24-h control blood pressure, maximum mean reductions in systolic and diastolic blood pressures of 33 and 21 mm Hg, respectively, were noted in patients receiving fenoldopam at 0.8 microg/kg/min and occurred 4 and 1 h, respectively, after beginning infusion. Tolerance to the blood pressure lowering effects of the drug developed slowly during the 48 h of drug infusion; the half-life for this effect was 60 h. No serious adverse clinical effects were noted in any patient. These results demonstrate that fenoldopam is effective in reducing blood pressure of patients with mild-to-moderate hypertension at doses as low as 0.04 microg/kg/min, is well tolerated at doses up to 0.8 microg/kg/min, maintains most of its antihypertensive efficacy throughout 48 h of continuous, constant rate infusion, and produces neither prolonged pharmacodynamic effects nor rebound hypertension when discontinued. The pharmacodynamic effects of the drug are best predicted by pharmacokinetics of racemic and R-fenoldopam.

Fenoldopam: a new parenteral antihypertensive: consensus roundtable on the management of perioperative hypertension and hypertensive crises

A panel of clinicians from anesthesiology, surgery, nephrology, hypertension, cardiology, and pharmacology was convened to discuss pharmacologic therapeutics in the management of hypertensive crisis and perioperative hypertension. The panel discussed the advantages and limitations of currently available parenteral drugs, and assessed the potential use of fenoldopam mesylate, a drug in clinical development since 1981, and recently approved by the U.S. Food and Drug Administration (FDA). Fenoldopam is a dopamine receptor (DA1 selective) agonist that is a systemic and renal vasodilator. It was concluded that fenoldopam offers significant advantages as a parenterally administered agent for the management of blood pressure in both hypertensive emergencies and in the perioperative setting.

Sustained hemodynamic effects of the selective dopamine-1 agonist, fenoldopam, during 48-hour infusions in hypertensive patients: a dose-tolerability study

Eight patients with stage I-II hypertension received a continuous IV infusion of the selective dopamine-1 agonist, fenoldopam, for up to 48 hours at rates from 0.4 to 1.9 micrograms/kg/min. Hemodynamics and clinical symptoms during infusion were compared to the same parameters in the 24-hour periods before and after infusion. Fenoldopam lowered blood pressure and increased heart rate. Greatest changes occurred during the first 12 hours of infusion and gradually returned toward preinfusion values throughout the remaining 36 hours in the six patients who completed 48 hours of infusion. Fenoldopam was discontinued within 2 hours of starting the infusion in two patients who received drug rates of 0.9 microgram/kg/min and 1.9 micrograms/kg/min because of precipitous bradycardia. Clinical symptoms noted at fenoldopam doses higher than 0.8 microgram/kg/min were headache, dizziness, diaphoresis, nausea and vomiting, and restlessness. In this pilot study, fenoldopam effectively reduced blood pressure in patients with stage I-II hypertension for up to 48 hours, but fixed-dose infusion rates above 0.8 microgram/kg/min were associated with a high frequency of clinically significant and often intolerable adverse effects.

Peripheral versus central potencies of N-type voltage-sensitive calcium channel blockers

The ability of a series of synthetic analogues of omega-conopeptides MVIIA (SNX-111) and TVIA (SNX-185) to prevent electrically-evoked norepinephrine release from rat tail artery and hippocampal slice preparations was determined in an effort to identify voltage-sensitive calcium channel (VSCC) blockers that selectively target N-type VSCCs in central nervous system tissue. Electrical field stimulation (3 Hz, 1 ms in duration. 80 V for 1 min) caused a high and consistent tritium outflow from rat tail artery and hippocampal slice preparations preloaded with [3H]-norepinephrine. All conopeptides, chosen for their selective affinities for high-affinity SNX-111 binding sites (i.e., N-type VSCCs) over high-affinity omega-conopeptides MVIIC (SNX-230) binding sites (i.e., P/Q-type VSCCs), produced a concentration-dependent inhibition of calcium dependent electrically-evoked tritium outflow from both tail arteries and hippocampal slices: IC50s ranged from 1.2 nM to 1.2 microM. Blocking potencies (IC50s) in the tail artery assay were significantly correlated with those measured in the hippocampal slice preparation (r = 0.91, P = 0.00000012). There was a significant correlation between IC50s for blockade of hippocampal norepinephrine release and the inhibition of high-affinity [125I]-SNX-I11 binding in rat brain synaptosomes (r = 0.76, P = 0.00028). Blockade of hippocampal norepinephrine release was not significantly correlated with the inhibition of high-affinity SNX-230 binding (r = 0.46, P = 0.056). Maximum inhibition of tritium outflow in the tail artery assay was 22+/-1.4% of control, approximating the value (20.9+/-16.0% of control) obtained in the absence of extracellular Ca2+. In contrast, the maximum inhibition of tritium release from hippocampal slices was 36.8+/-2.5% of control (P < 0.05, compared to that of the tail artery assay). These results suggest that (1) N-type VSCCs alone mediate low frequency electrical stimulation-evoked neurotransmitter release from peripheral sympathetic efferents (tail artery) while both N-type and non-N type(s) mediate neurotransmitter release from CNS neurons (hippocampus); and (2) analogues of omega-conopeptides MVIIA and TVIA do not differentiate between N-type VSCCs mediating norepinephrine release from central and peripheral neural tissues.

The management of severe chronic pain with a focus on new treatment modalities

Pain is the most common reason for consultation with a physician, but because pain is not objectively measurable, it is often neglected or underestimated. Chronic, severe pain is a major complication of cancer and HIV-1 infection. Current therapy typically employs stepwise treatment first with nonopioid analgesics, followed by weak and then strong opioids. Nevertheless, treatment can be limited both by side effects and by the development of tolerance, and patients with neuropathic pain are often resistant to all conventional therapies. Much has been learned about the neuroanatomy and physiology of both acute and chronic pain. Drugs now being developed, such as alpha(2)-receptor agonists, the N-type calcium channel blocker, SNX-111 and NMDA antagonists, take advantage of current knowledge of the neurochemistry of pain transduction and target neurotransmitter modulation as a means of achieving analgesia. These new drugs and alternative administration methods, such as intraspinal drug delivery and preemptive analgesia for postoperative pain, should add substantially to the current analgesic armamentarium.

Sympatholysis after neuron-specific, N-type, voltage-sensitive calcium channel blockade: first demonstration of N-channel function in humans

SNX-111 is the first neuronal N-type, voltage-sensitive calcium channel (VSCC) blocker to enter clinical drug development. Areas of potential therapeutic utility include treatment of nociceptive and neuropathic pain and neuroprotection after ischemic brain injury. The data presented demonstrate that SNX-111 is biologically active in humans and indicate for the first time a neurophysiologic function of N-type VSCCs in humans.

Use of intrathecal SNX-111, a novel, N-type, voltage-sensitive, calcium channel blocker, in the management of intractable brachial plexus avulsion pain

OBJECTIVE

The objective was to assess the analgesic, antihyperesthesic, and anti-allodynic properties of SNX-111 in neuropathic pain.

DESIGN

We describe a patient with refractory, severe deafferentation pain successfully treated with SNX-111 in an open-label, baseline-controlled Phase I/II trial.

SETTING

The patient was hospitalized for treatment and observation.

PATIENT

The patient was a 43-year-old man with intractable deafferentation pain of 23 years' duration secondary to brachial plexus avulsion.

INTERVENTION

SNX-111, the first neuron-specific, N-type, voltage-sensitive calcium channel blocker developed for clinical use, was administered by continuous, constant-rate, intrathecal infusion via an indwelling cervical catheter.

OUTCOME MEASURES

The primary outcome measures were the Visual Analog Scales of Pain Intensity (VASPI) and Pain Relief (VASPR).

RESULTS

The patient experienced complete pain relief (VASPI = 0.0 cm and VASPR = 10.0 cm) with elimination of hyperesthesia and allodynia.

CONCLUSIONS

SNX-111, administered intrathecally by continuous, constant-rate infusion, produced dose-dependent pain relief in a 43-year-old male patient with a 23-year history of intractable deafferentation and phantom limb pain secondary to brachial plexus avulsion and subsequent amputation. Dizziness, blurred vision, and lateral-gaze nystagmus were dose-dependent side effects that resolved with decreasing dose levels. Complete pain relief was achieved in this patient without side effects after dose adjustment. We conclude that SNX-111 is a potent analgesic, antihyperesthesic, and antiallodynic agent. Controlled studies of SNX-111 in patients with malignant and nonmalignant pain syndromes are warranted and are under way.

Pharmacokinetics of SNX-111, a selective N-type calcium channel blocker, in rats and cynomolgus monkeys

SNX-111, a selective N-type voltage-sensitive calcium channel blocker, is in clinical trials for the treatment of ischemia-induced brain injury and chronic pain. Pharmacokinetic studies were conducted in rats and cynomologus monkeys to determine the disposition of this compound when it is administered for 24 hr by continuous, constant-rate intravenous infusion. Venous blood samples for determination of SNX-111 plasma levels were collected at regular intervals immediately before, during, and after dosing. Plasma concentrations of SNX-111 equivalents were measured by radioimmunoassay. Pharmacokinetic parameters were derived from plasma SNX-111 concentration-time data using a two-compartment pharmacokinetic model. Results showed close correspondences between pharmacokinetic parameters determined for both species. There were no consistent gender- or dose-related differences in calculated kinetic parameters. In all cases, apparent steady-state plasma SNX-111 concentrations were achieved within 2-4 hr of initiating SNX-111 infusion. Steady-state volume of distribution values were approximately 40% of body weight, indicating extravascular dissemination of SNX-111 to both extracellular and intracellular fluids. Elimination curves contained two exponential components. The fast component (rat t1/2, alpha = 0.375 hr; monkey t1/2, alpha = 0.730 hr) accounted for approximately 97% of the unit impulse disposition function. The apparent terminal half-life ranged from 4.61 hr (rat) to 6.48 hr (monkey). Current findings constitute the first description of the pharmacokinetics of a member of the omega-conopeptide family of neuronal calcium channel blockers.

Selective blockade of N-type voltage-sensitive calcium channels protects against brain injury after transient focal cerebral ischemia in rats

The neuroprotective efficacy of the selective N-type voltage-sensitive calcium channel blocker, SNX-111, was evaluated in spontaneously hypertensive rats subjected to 60 min of focal cerebral ischemia by permanent ligation of the right common carotid artery and temporary occlusion of the right middle cerebral artery. Intravenous infusion of 167 microg/kg per min SNX-111 for 30 min (5 mg/kg), initiated immediately after reperfusion, significantly reduced cortical infarct volumes measured 24 h after the ischemic insult.

Selective N-type neuronal voltage-sensitive calcium channel blocker, SNX-111, produces spinal antinociception in rat models of acute, persistent and neuropathic pain

Male Sprague-Dawley rats were used to evaluate the antinociceptive properties of the selective N-type voltage-sensitive calcium channel (VSCC) blocker, SNX-111, when the compound is administered spinally by either bolus injection or continuous, constant-rate infusion into the subarachnoid space. SNX-111 produced significant, dose-dependent antinociceptive effects by suppressing both the acute (phase 1: ED50, 14 ng/hr) and tonic (phase 2: ED50, 0.82 ng/hr) phases of the formalin test when it was infused for 72 hr immediately before testing. Phase 2 nociceptive responses were suppressed by bolus injections of 100 ng SNX-111. SNX-111 was approximately 1000-fold more potent than morphine in blocking phase 2 responses when the compounds were administered by intrathecal bolus injection. In rats with an experimentally induced painful peripheral neuropathy, intrathecal bolus injections of 30 to 300 ng SNX-111 blocked mechanical allodynia in a dose-dependent manner. Subacute administration of SNX-111 (1, 10 and 100 ng/hr) by continuous intrathecal infusion produced a reversible blockade of mechanical allodynia without apparent development of tolerance. These results show that: 1) selective N-type VSCC blockers are potent and efficacious antinociceptive agents when they are administered by the spinal route; 2) selective N-type VSCC blockers are effective in rat models of acute, persistent and neuropathic pain; and 3) N-type VSCCs play a significant role in the spinal processing of noxious somatosensory input.

Simultaneous modeling of the pharmacokinetic and pharmacodynamic properties of enalkiren (Abbott-64662, a new renin inhibitor). I: Single dose study

This study describes the relationship between the measured effects (angiotensin I and renal plasma flow) and plasma drug levels using a combined pharmacokinetic-pharmacodynamic model after 90 min iv infusion of enalkiren in 15 healthy, salt-depleted subjects. Doses from 0.002 to 0.512 mg/kg were evaluated. One hour prior to enalkiren dosing, para-aminohippuric acid infusion was started for each subject and continued until 3 hr after the start of enalkiren infusion. Timed blood samples were obtained to measure enalkiren, para-aminohippuric acid, and angiotensin I levels in plasma. Enalkiren-induced effect changes lagged in time behind the plasma enalkiren level changes, showing a counterclockwise hysteresis loop. To relate the temporal relationship of effect changes accurately to plasma drug levels, a pharmacokinetic model was combined with a pharmacokinetic model that incorporated a hypothetical effect compartment. The magnitude of the time lag was quantified by the half-time of equilibration between concentrations in the hypothetical effect compartment and the plasma enalkiren levels (t1/2keo). The t1/2keo for angiotensin I (0.002 hr) is significantly shorter than that of renal plasma flow (0.267 hr), indicating that enalkiren equilibrates more rapidly with the angiotensin I-related effect compartment than the renal plasma flow-related effect compartment. Moreover, the model allows for estimation of the effect site concentration that causes one-half of the maximal predicted effect (EC50), which is a measure of an individual's sensitivity to enalkiren. The EC50 of angiotensin I (81.1 ng/ml) is substantially lower than that of renal plasma flow (4414 ng/ml), indicating that angiotensin I may be a more sensitive measure of enalkiren effects than renal plasma flow.

Immediate blood pressure effects of the renin inhibitor enalkiren and the angiotensin-converting enzyme inhibitor enalaprilat

The antihypertensive effects of the renin inhibitor enalkiren were compared with those of the angiotensin-converting enzyme inhibitor enalaprilat in 17 hypertensive patients (14 white, 3 black; mean age 57 years), whose renin systems had been stimulated by diuretic pretreatment. Patients were studied on 3 separate in-hospital days. On the first study day patients received placebo alone. On day 2 they received intravenous bolus doses of enalkiren (0.03 to 1.0 mg/kg), and on day 3, intravenous bolus doses of enalaprilat (0.625 to 1.25 mg). Each agent reduced systolic (p less than 0.01) and diastolic (p less than 0.01) blood pressure (BP) from baseline levels. The acute decrease in systolic BP of 18.5 +/- 0.4 mm Hg during enalkiren tended to be greater (p less than 0.01) than the decrease of 12.6 +/- 0.7 mm Hg during enalaprilat. Decreases in diastolic BP during enalkiren (11.9 +/- 0.4 mm Hg) were also slightly greater (p less than 0.1) than those during enalaprilat (9.2 +/- 0.4 mm Hg). Based on prestudy plasma renin activity (PRA), patients were divided into "high" renin (PRA greater than 3.5 ng angiotensin l/ml/hr; n = 6) and "low/normal" renin (less than 3.5 ng angiotensin l/ml/hr; n = 11) groups. Reductions in diastolic BP in the "high" renin group during enalkiren (30 +/- 5/20 +/- 3 mm Hg) tended to be greater (p less than 0.07) than those during enalaprilat (23 +/- 7/14 +/- 1 mm Hg); differences were not significant in the "low/normal" group (12 +/- 2/7 +/- 2 and 7 +/- 2/8 +/- 1 mm Hg, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Renin inhibitors in hypertension

The renin-angiotensin system (RAS) is an important modulator of blood pressure and fluid balance. The clinical success of angiotensin converting enzyme inhibitors (ACEIs) in the treatment of hypertension has stimulated the search for antagonists of renin. Because renin is highly specific for its substrate, angiotensinogen, renin inhibitors may emerge as clinically preferable alternatives to ACEIs, which affect multiple biological systems, including bradykinin and prostaglandin metabolism. Recent advances in renin inhibitor chemistry have produced highly specific and potent, transition-state analogs of angiotensinogen. Several compounds (e.g., enalkiren, ditekiren, CGP 38560A, and RO 42-5892) have been tested in man. These renin inhibitors produce dose-dependent decreases in plasma renin activity (PRA) which are dissociated from the dose-dependent decreases in blood pressure (BP). Potential explanations for this dissociation include methodologic errors in PRA assays and alternate sites or mechanisms of drug action, including inhibition of noncirculating tissue renin. A prolonged hypotensive effect is seen following single doses of enalkiren and RO 42-5892, and repeated dosing with enalkiren results in sustained hypotensive effect without tachyphylaxis. Renin inhibitors can reduce blood pressure irrespective of baseline renin status and sodium balance. However, high-renin patients generally respond more vigorously, and the hypotensive response is enhanced by sodium depletion. In general, renin inhibitors have been safe and well tolerated in limited clinical studies. New generation renin inhibitors with higher potency and greater oral bioavailability may join the antihypertensive armamentarium.

Antihypertensive dose-response relationships: studies with the selective alpha 1-blocking agent terazosin

Terazosin is a selective alpha 1-adrenergic-blocking agent indicated for the treatment of hypertension. The aim of this multicenter study, performed in 256 patients with mild to moderate essential hypertension, was to define the dosing characteristics of terazosin (in the range of 1 to 80 mg) administered once daily. Patients were randomly assigned to placebo or active treatment groups; each group received 3 months of treatment, which comprised three ascending doses of terazosin, each administered for a 1-month period. As determined by conventional office measurements of supine diastolic blood pressure and by automated ambulatory blood pressure monitoring, there was a clear antihypertensive dose-response relationship for terazosin in the range of 1 to 5 mg daily. Except for the 80 mg dose, none of the doses above 5 mg (10 to 40 mg) appeared to provide additional efficacy. Both the office measurements and the monitoring data indicated that the ratio of trough (effect at the end of the dosing interval) to peak (maximum effect during the dosing interval) was at least 50% or greater during treatment with the 5 mg dose. Thus the 5 mg dose appeared to provide meaningful clinical antihypertensive efficacy and to sustain its effects throughout the full 24-hour period.

Effects of renin inhibition in systemic hypertension

The effect of the direct renin inhibitor enalkiren (Abbott Laboratories) was examined in 8 healthy patients with essential hypertension. With an unrestricted sodium diet, plasma renin concentration was inhibited within 10 minutes by intravenous enalkiren and remained essentially undetectable for greater than or equal to 6 hours (11.9 +/- 4 to 1.0 +/- 0.6 ng angiotensin I/ml/hour, p less than 0.05). Mean arterial blood pressure declined gradually (108 +/- 5 to 84 +/- 4 mm Hg, p = 0.02), as did plasma aldosterone concentration (14.4 +/- 3.8 to 4.4 +/- 0.8 ng/dl, p = 0.03), whereas plasma immunoreactive active renin concentration increased progressively (35 +/- 14 to 160 +/- 60 pg/ml, p greater than 0.05). Urinary excretion of the stable metabolite of prostacyclin (6-keto-prostaglandin F1 alpha) decreased slightly, but not significantly (42 +/- 10 to 33 +/- 11 ng/g creatinine, p = 0.13). The addition of a diuretic decreased baseline blood pressure and increased baseline plasma renin and aldosterone values. Blood pressure responses to enalkiren were slightly (though not significantly) greater than those observed before diuretic administration. We conclude that enalkiren is effective in decreasing blood pressure and in inhibiting the renin system, without significantly altering urinary prostacyclin excretion, in patients with essential hypertension. These results suggest that the renin system contributes to the maintenance of elevated blood pressure in some patients with essential hypertension.

Prolonged duration of blood pressure response to enalkiren, the novel dipeptide renin inhibitor, in essential hypertension

The effects of sustained renin inhibition by repeated administration of enalkiren (A-64662), the novel dipeptide renin inhibitor, were evaluated in a randomized, double-blind, placebo-controlled, parallel-group study of 32 inpatients (eight per group) with essential hypertension who were maintained on a diet containing 60 meq/day sodium. Three different dosage regimens of enalkiren were studied: 1) 1.2 mg/kg quotid., 2) 0.3 mg/kg q.i.d., and 3) 0.1 mg/kg q.i.d. Each patient received an intravenous infusion every 6 hours for 1 week. Placebo infusions were used to mimic the 4 times/day dosing schedule. Blood pressure was measured periodically via 24-hour automated monitoring equipment. Mean plasma renin activity in the patient groups ranged from 1.58 to 2.68 ng angiotensin I/ml/hr. Plasma renin activity was promptly suppressed in all groups receiving enalkiren. Prolonged duration of plasma renin activity suppression (greater than or equal to 24 hours) was demonstrated after the administration of 1.2 mg/kg enalkiren. The 0.3 mg/kg q.i.d. and 1.2 mg/kg quotid. regimens produced statistically significant reductions (p less than or equal to 0.05) in systolic and diastolic blood pressures with clear evidence of persistent antihypertensive activity for 12 hours or more when compared with the placebo group. Despite relatively large reductions in mean systolic and diastolic blood pressure, mean pulse rates were essentially unchanged. The prolonged reduction in blood pressure with enalkiren without evidence of tachyphylaxis after 1 week of treatment suggests that renin inhibitors may emerge as useful therapeutic agents for the treatment of hypertension.

Effects of terazosin on serum lipid levels in hypertensive blacks

The effects of terazosin, a new, selective, alpha 1-adrenoceptor antagonist, on the serum lipid levels were examined in 103 black patients with uncomplicated, mild to moderate essential hypertension in six randomized, double-blind, placebo-controlled trials conducted in the United States. Terazosin produced statistically significant (P less than 0.05) reductions in total serum cholesterol and triglyceride levels and a marginally significant (P = 0.080) reduction in the combined low-density lipoprotein (LDL-C) and very-low-density lipoprotein (VLDL-C) cholesterol fraction when compared with placebo. We conclude that terazosin, unlike thiazide diuretics, has a favourable effect on the serum lipid profiles of hypertensive blacks.

Efficacy of terazosin in the treatment of essential hypertension in blacks

The antihypertensive effects of the selective alpha 1-adrenoceptor antagonist, terazosin, in black patients with uncomplicated, mild to moderate essential hypertension were examined retrospectively in seven randomized, double-blind, placebo-controlled trials conducted in the United States. Following 4 to 13 weeks of treatment with terazosin (2-40 mg, once daily), supine and standing systolic and diastolic blood pressures were decreased significantly from baseline, and these decreases were significantly greater than those observed in the placebo group (P less than 0.05). Blood pressure changes in the black and white patient subgroups were comparable. Terazosin was generally well tolerated with a low incidence of serious side effects. We conclude that terazosin is a safe and effective antihypertensive agent in black patients with essential hypertension.

Clinical pharmacology of enalkiren, a novel, dipeptide renin inhibitor

Enalkiren (A-64662), a potent, dipeptide renin inhibitor, mimics the transition state of the human renin substrate, angiotensinogen. Enalkiren has been shown to produce dose-related suppression of plasma renin activity (PRA) and angiotensin II when administered intravenously. Doses of enalkiren of less than 0.1 mg/kg induced little hemodynamic response in normotensive and hypertensive volunteers despite marked suppression of PRA. However, at doses of 0.3 and 1.2 mg/kg, enalkiren produced significant, dose-related decreases in systolic and diastolic blood pressure (BP) in hypertensive patients, and the BP response was enhanced by pretreatment with hydrochlorothiazide. The effects of enalkiren on PRA and BP are prolonged despite its relatively short elimination phase plasma half-life (1.6 h). Persistent pharmacologic activity without evidence of tachyphylaxis was demonstrated during 1 week of treatment in hypertensive patients. The observed dissociation between suppression of PRA and BP response and the recruitment of dose-related BP decrements, despite complete suppression of PRA, are unexplained phenomena. The results of clinical trials with enalkiren are encouraging, and suggest that renin inhibitors may be safe, useful therapeutic agents in the management of hypertension.

New perspectives on selective alpha 1 blockade

Selective alpha 1 adrenergic receptor blocking agents lower blood pressure by reducing the increased peripheral vascular resistance that characterizes essential hypertension. Prazosin and terazosin have been shown to be well tolerated in clinical practice and seldom cause impotence or metabolic abnormalities. The most common adverse effects--dizziness, headache, and asthenia--are generally well tolerated and infrequently lead to discontinuation of therapy. First-dose syncope can usually be avoided by initiating therapy with low doses administered at bedtime. Finally, the alpha 1 receptor antagonists do not adversely affect such cardiovascular risk factors as hypokalemia, serum lipid profile, and left ventricular hypertrophy. In fact, alpha 1 antagonists reduce total cholesterol and low-density-lipoprotein plus very-low-density-lipoprotein cholesterol and thus may contribute to the overall management of cardiovascular risk by blood pressure reduction and improvement of the serum lipid profile. Since the goal of treating chronic essential hypertension is to improve morbidity and mortality, the choice of therapy should be influenced by the agent's ability to modify as many risk factors as possible. Alpha 1 adrenoreceptor antagonists beneficially impact several cardiovascular risk factors and thus merit consideration as first-line antihypertensive therapy.

Terazosin: a new antihypertensive agent with favorable effects on lipids

Terazosin is a new, selective, alpha 1-adrenoceptor antagonist which is structurally similar to prazosin and of similar therapeutic efficacy in the treatment of mild-to-moderate essential hypertension. Unlike prazosin, the terminal-phase plasma half-life is long, at approximately 12 h, and effective blood pressure control is usually achieved with a once-daily dosing regimen. Once-daily dosing improves patient compliance, and good compliance to the therapeutic regimen is essential to effective treatment and the reduction of cardiovascular morbidity and mortality. Terazosin has generally been well tolerated in short-term and long-term studies. Unlike diuretics and beta-blockers, terazosin does not adversely affect the serum lipid profile. Indeed, beneficial changes in the serum lipid profile have been observed in patients with hypertension. In placebo-controlled trials, total serum cholesterol and the combined low-density plus very-low-density lipoprotein cholesterol fraction were significantly reduced from baseline in the terazosin-treated group when compared with the placebo-treated group. In addition, terazosin tended to produce increases from baseline in the high-density lipoprotein cholesterol fraction and decreases in serum triglyceride levels. Once-daily dosing and a favorable impact on the serum lipid profile support the use of terazosin as first-choice treatment for mild-to-moderate essential hypertension.

The effects of terazosin and methyclothiazide on blood pressure and serum lipids

This study compared the antihypertensive efficacy and the effects on serum lipids of terazosin, a new selective alpha 1-adrenergic antagonist, of methyclothiazide (MCTZ), and of the two drugs used as combination therapy. Adult patients with supine diastolic blood pressure ranging from 95 to 120 mm Hg were eligible to enter this double-blind, randomized, parallel-group study. Analyses of the blood pressure data from the 194 evaluable patients revealed that all three treatments produced significant (p less than 0.001) reductions in supine and standing systolic and diastolic blood pressures from baseline values. Moreover, combination therapy resulted in significantly greater mean blood pressure reductions than were observed with either drug used as monotherapy. In the group receiving terazosin monotherapy, the total serum cholesterol level, low-density lipoprotein plus very-low-density lipoprotein cholesterol fraction, and triglyceride level fell significantly (median changes of 3.7%, 5.0%, and 16.3%, respectively, p less than 0.05). However, in the group receiving MCTZ monotherapy, the total serum cholesterol level, low-density lipoprotein plus very-low-density lipoprotein cholesterol fraction, and triglyceride level increased significantly (4.7%, 7.1%, and 12.5%, respectively, p less than 0.001). In contrast, no significant changes from baseline values were observed for any lipid variable in the group receiving terazosin/MCTZ combination therapy. We conclude that terazosin is effective antihypertensive therapy that has a potentially beneficial effect on the serum lipid profile when used as monotherapy and that it counteracts the negative impact of MCTZ monotherapy on the serum lipid profile when used concurrently with this thiazide diuretic.

Toxicity of uricosuric diuretics in rat hepatocyte culture

Several aryloxyacetic acid diuretics have shown hepatotoxicity in humans, yet there continues to be interest in developing these compounds because of the uricosuric properties of some of them. This study was designed to test the utility of the hepatocyte monolayer culture as a model for studying these compounds. In addition, an attempt was made to define the structural components that are common to hepatotoxicity. Ticrynafen, indacrinone, ethacrynic acid and A-49816, an investigational compound, were found to be toxic in hepatocyte cultures; thus, with the exception of indacrinone, paralleling the experience in humans. The toxic compounds share a ketodichlorophenoxyacetic acid chemical structure. A-56234, an investigational uricosuric, was also found to be toxic in cultures but has not been demonstrated to be hepatotoxic in humans in limited clinical experience. It does not possess the ketodichlorophenoxyacetic acid structure proper but may be metabolized to a closely related structure. Furosemide, which does not have the ketodichlorophenoxyacetic acid structure, was not toxic in hepatocyte cultures and has not been hepatotoxic in humans. Thus, the structure common to the toxic compounds is ketodichlorophenoxyacetic acid or a closely related compound. The hepatocyte monolayer system appears to be a good model for demonstrating toxicity and, perhaps, for predicting toxicity of new compounds under development.

Renin inhibitors: specific modulators of the renin-angiotensin system

1. Angiotensin II (AII) acts as a potent pressor agent directly, by virtue of its vasoconstrictor activity and indirectly, by the volume expansion resulting from stimulation of aldosterone release from the adrenal cortex, leading to sodium and water retention. Various approaches of interfering with the enzymatic cascade leading to the production of AII have been made in an attempt to define therapeutic agents for the control of hypertension and heart failure. 2. AII receptor antagonists, to date, lack oral activity and have a relatively short duration of action, limiting their clinical usefulness. Inhibitors of angiotensin converting enzyme block AII production, are orally active and have been used successfully in the control of hypertension and in the treatment of congestive heart failure. 3. An ideal approach to the blockade of the renin-angiotensin system (RAS) is the inhibition of renin, an enzyme with only one known substrate (angiotensinogen) which catalyzes the first and rate-limiting step in the RAS. Early attempts to discover a renin inhibitor focused on immunologic inhibitors of renin, fragments of the prorenin sequence and compounds related to pepstatin, a potent pentapeptide inhibitor of pepsin and less potent inhibitor of renin. None of these approaches proved feasible for a variety of reasons including poor absorption, short duration of action and weak activity. 4. Substrate analogs offer the greatest promise for clinically useful renin inhibitors. Most recently, synthesis of compounds mimicking the enzyme transition state, the condition of greatest binding affinity, has resulted in renin inhibitors with potencies in the nanomolar range, which have shown hypotensive activity. These compounds contain at least one peptide bond and have limited oral activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacologic effects of A-56234, a new high-ceiling diuretic

The pharmacokinetic characteristics, the diuretic, saluretic, and uricosuric properties, and the safety of single, rising, oral doses of A-56234, a new high-ceiling diuretic, were evaluated in this double-blind, placebo-controlled, cross-over study. Each of three groups of eight subjects received placebo and three different single doses of the diuretic at 1-week intervals. Doses ranged from 0.5 to 80 mg. Significant, dose-related increases in urine volume and in urinary excretion of sodium and chloride were produced during the 24 hours after administration of 20, 40, 60, and 80 mg of the drug. Uricosuria was not observed at any dose. The drug was rapidly absorbed and displayed linear pharmacokinetics within the dose range studied. The elimination-phase plasma half-life was approximately 6 hours. Hepatic clearance was the main route of excretion in humans; only 2 to 10% of the parent drug was excreted in the urine. The drug was well tolerated and no clinically important adverse events were noted.

Terazosin, a new selective alpha 1-adrenergic blocking agent. Results of long-term treatment in patients with essential hypertension

The long-term treatment of essential hypertension with terazosin, a new once-a-day alpha 1-adrenergic blocking agent, was evaluated in 364 hypertensive patients who received total daily doses of 1 to 40 mg for 3 weeks to 56 months. Consistent mean decreases in supine and standing systolic and diastolic blood pressures were observed throughout the study for patients treated with terazosin as monotherapy (supine, 9 to 12/10 to 13 mm Hg; and standing, 12 to 18/11 to 14 mm Hg) or in combination with other antihypertensive agents (supine, 12 to 16/12 to 15 mm Hg; and standing, 16 to 22/13 to 19 mm Hg). The most commonly reported adverse experiences were dizziness, headache, asthenia, cold symptoms, and nasal congestion. Adverse effects and metabolic disorders often associated with diuretics and beta blockers such as sexual dysfunction, hyperglycemia, hyperuricemia, hypokalemia, or adverse lipid effects were seen infrequently during long-term treatment with terazosin as monotherapy. Overall, terazosin was shown to be effective, safe, and well tolerated by most patients.

A comparison of carteolol and nadolol in the treatment of stable angina pectoris

In a multicenter, dose-ranging, double-blind study, 63 patients diagnosed as having stable angina pectoris were randomly assigned to treatment with carteolol (33 patients) or nadolol (30 patients). Following a 2 to 4-week dose-ranging period, an optimal dose was determined for each patient and treatment with that dose continued for 6 weeks. Data from all 63 patients were analyzed for drug safety; data for 52 patients (27 carteolol and 25 nadolol) were analyzed for drug efficacy. The most commonly chosen dosage levels were 20 mg of carteolol and 80 mg of nadolol. There were no statistically significant differences between the carteolol and nadolol groups in changes in exercise tolerance as reflected by time to onset of angina, end-point of exercise, and onset of 1 mm ST segment change on ECG. Both drugs significantly suppressed tachycardia and double product during treadmill exercise. The nadolol-treated group demonstrated a significantly greater reduction in resting heart rate (18.7 bpm) as compared with the carteolol-treated group (3.1 bpm). Carteolol possesses intrinsic sympathomimetic activity (ISA), which may account for the fact that carteolol effectively reduces exercise-induced tachycardia while producing relatively little effect on resting heart rate. The frequency of anginal attacks and the use of sublingual nitroglycerin were reduced to a similar extent in both treatment groups. The most commonly reported side effect in both treatment groups was asthenia.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of the renin inhibitor A-64662 in monkeys and rats with varying baseline plasma renin activity

The efficacy of the potent, primate selective renin inhibitor A-64662 was studied in monkeys and rats with varying baseline plasma renin activity (PRA) to elucidate the relationship between PRA and the hypotensive response induced by this compound. The effect of a single bolus of vehicle or A-64662 at 0.001, 0.01, 0.1, 1.0, and 10.0 mg/kg i.v. was compared in 30 normal and 30 salt-depleted, anesthetized monkeys (n = 5/dose). Baseline mean arterial pressure (MAP) was similar among all groups, but baseline PRA was elevated in salt-depleted monkeys. A-64662 induced a comparable dose-related fall in MAP, affecting the magnitude and duration of action, accompanied by inhibition of PRA, the duration of which was dose-related in both the normal and salt-depleted groups. However, the minimum effective doses required to reduce MAP by approximately 10% were 0.01 mg/kg for the salt-depleted monkeys and 0.1 mg/kg for the normal monkeys. In a second study, three consecutive boluses of vehicle or A-64662 at 0.1, 1.0, and 10.0 mg/kg were administered to anephric monkeys, human renin-infused anephric monkeys, and normal monkeys (n = 4/group). A dose of 0.1 mg/kg was ineffective, but the 1.0 mg/kg dose lowered MAP by 11 +/- 3% (mean +/- SE) in the anephric monkeys. The infusion of renin into anephric monkeys restored the efficacy of A-64662 at the 0.1 and 1.0 mg/kg doses to responses comparable to those of the normal monkeys. A-64662 at 10.0 mg/kg caused a similar fall in MAP of 50 to 60% in anephric, renin-infused anephric, and normal monkeys in the absence of detectable PRA.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacologic effects of A-49816, a new high-ceiling diuretic

The pharmacologic effects of A-49816, a high-ceiling, loop diuretic, were evaluated in a single-blind, placebo-controlled, randomized trial. Eighteen (18) normal volunteers aged 19 to 40 years were divided into three groups. The subjects in each group received either placebo or three increasing doses of A-49816 with at least a one-week washout between doses. Nine doses of A-49816 (0.5 to 20 mg) were administered during the entire study. Urine volume and excretion of electrolytes were measured at timed intervals following dosing. A-49816 increased urine volume and excretion of sodium and chloride. Significant saluresis, chloruresis and diuresis were seen in most time periods following administration of the highest doses (12.5, 15 and 20 mg) of A-49816. Kaluresis was not consistently seen at any dose. The mean rates of urine output and sodium and chloride excretion were increased relative to placebo within 2 hours of drug administration. The mean rates of urine formation and sodium and chloride excretion peaked at 2-4 hours and often remained elevated at the 6-12 hour interval.

Terazosin: a new alpha 1-blocker for the treatment of hypertension: a review of randomized, controlled clinical trials of once-daily administration as monotherapy

Terazosin, a new selective long-acting alpha1-adrenergic blocking agent, has been shown to be an effective once-daily antihypertensive agent in four of five randomized double-blind placebo-controlled studies of patients with mild to moderate hypertension. In one trial, 24-h monitoring revealed that terazosin produced a sustained blood pressure lowering effect throughout the day. In three fixed-dose trials, steady patterns of blood pressure response during maintenance therapy indicated that tolerance to terazosin did not develop. Favourable changes in the plasma lipid profile were observed, while laboratory data suggested the development of haemodilution. Overall, terazosin was well tolerated. Asthenia, dizziness and peripheral oedema were significantly more common in patients treated with terazosin than with placebo.

Long-term treatment of angina pectoris with carteolol: a new beta-adrenergic receptor blocking agent

Seventy-two patients entered the treatment phase of an open, long-term, dose-ranging trial of carteolol in stable, exercise-induced angina pectoris. Patients were to be treated with progressive doses of carteolol (2.5, 5, 10, 20, 40, and 60 mg), given as a single daily oral dose. Thirty of the patients (42%) completed one year of treatment with carteolol as the sole antianginal therapy. The most frequent final carteolol doses were 20 mg and 40 mg once daily. Statistically significant improvements from baseline in exercise tolerance as reflected in time to onset of angina, time to the endpoint of exercise and time to the onset of 1 mm S-T segment change on ECG were observed in carteolol-treated patients. Exercise-induced increases in heart rate and double-product were significantly suppressed, compared to baseline, throughout the study. Resting heart rate and double-product were modestly decreased. Carteolol was shown to be effective and safe when administered on a long-term basis to patients with angina pectoris.

Carteolol treatment of essential hypertension: a long-term study of safety and efficacy

The long-term safety and antihypertensive efficacy of carteolol were evaluated in an open-label, multicenter trial of 245 hypertensive patients. For those patients maintained on carteolol monotherapy, three months of treatment with once-daily oral doses of carteolol ranging from 2.5 to 60 mg reduced the mean recumbent blood pressure by 12/14 mm Hg from baseline values of 151/100. Blood pressure reductions observed at three months were maintained throughout the study. The final daily dose of carteolol for most patients was 10 mg or less. Carteolol was shown to be safe and well tolerated by most patients.

Clinical trials with terazosin. General methods

Terazosin has been studied in a variety of clinical trials conducted in hypertensive patients with supine diastolic blood pressures of 95 mm Hg or greater before treatment. Blood pressure, pulse rate, body weight, clinical laboratory variables, and adverse experience data were evaluated periodically throughout each study. Patients generally were seen at weekly or biweekly intervals. Total daily doses of terazosin ranged from 1 to 40 mg. Terazosin was administered alone and in combination with other antihypertensive agents. Clinical trials consisted of double-blind, controlled studies and long-term, follow-up studies. The controlled clinical trials employed three principal designs: studies in which the dose was titrated according to blood pressure response; studies in which the dose was increased to a fixed level regardless of blood pressure response; and randomized withdrawal studies. Efficacy evaluations were based on mean blood pressure changes from baseline to the final visit and on the distribution of patient responses, which were categorized from excellent to inadequate. Safety evaluations were based principally on comparisons of specific safety parameters before and after the study.

Overall safety of terazosin as an antihypertensive agent

The safety of terazosin, an effective agent for the treatment of hypertension, was assessed by analyzing data from 1,006 hypertensive patients who were enrolled in short-term and/or long-term studies. The total experience with terazosin in this article represents 422.5 patient-years. Changes in pulse rate measurements from pretreatment to posttreatment were not significantly different between the terazosin- and placebo-treated patients (-1.0 beat per minute for the terazosin group and -1.0 beat per minute for the placebo group, in the supine position). Dizziness, headache, and asthenia were the most commonly reported adverse experiences among all terazosin-treated patients, although the incidence of headache in placebo-controlled trials was not significantly different between the terazosin and placebo groups. As a whole, patients receiving terazosin had a tendency to gain small amounts of weight (2 pounds). In addition, there was a trend for slight decreases in hemoglobin, hematocrit, white blood cell count, total protein, and albumin levels in those patients who received terazosin, suggesting hemodilution. Overall, terazosin was shown to be safe in patients with mild to moderate essential hypertension.

Efficacy of terazosin as an antihypertensive agent

A total of 713 patients with hypertension were evaluated in eight randomized, double-blind, placebo-controlled trials of terazosin administered in single daily doses ranging from 1 to 40 mg. In three of these studies, terazosin or placebo was added to ongoing antihypertensive drug therapy. Patient response was categorized (from excellent to inadequate) according to the change in supine diastolic blood pressure from baseline and the value at the final visit. The distribution of patients in these response categories differed significantly between patients treated with terazosin and those treated with placebo. Overall, 52 percent of terazosin-treated patients in these eight studies, compared with 30 percent of placebo-treated patients, had good to excellent responses. Subgroup analysis revealed that blood pressure response was not dependent on sex or age, although white patients appeared to achieve better responses to terazosin in comparison with placebo than did black patients. These studies demonstrate that terazosin administered once daily, either as monotherapy or in combination with other antihypertensive agents, effectively controls blood pressure in patients with mild to moderate hypertension.

Anaphylaxis: etiology and guidelines for management

The successful management of anaphylaxis requires a thorough understanding of this syndrome and the application of various therapeutic agents. Although the mechanisms responsible for human anaphylaxis are not fully known, sufficient data and clinical experience are available to guide the anesthesiologist faced with this medical emergency.