Antihypertensive agents: mechanisms of action, safety profiles, and current uses in children

Comparison of surgical conditions in 2 different anesthesia techniques of esmolol-induced controlled hypotension in breast reduction surgery

BACKGROUND

Breast reduction surgery is a common cosmetic surgery with a high incidence of blood loss and transfusion. In this surgery, the reduction of blood loss related to surgical manipulation and the volume of resected tissue is a target. In the present study, we compared the effects of esmolol-induced controlled hypotension on surgical visibility, surgical bleeding, and the duration of surgery in patients anesthetized with propofol/remifentanil (PR) or sevoflurane/remifentanil (SR).

METHODS

Patients in the American Society of Anesthesiologists I/II risk group undergoing breast reduction surgery were prospectively randomized into PR (n = 25) and SR (n = 25) groups. Controlled hypotension was induced with esmolol in both groups. During the intraoperative period, the heart rate (HR), mean arterial pressure (MAP), operation duration, volume of intraoperative blood loss, volume of blood received through postoperative drains, volume of resected tissues, and surgical area bleeding score were recorded.

RESULTS

The duration of operation in the incisional period was shorter in group PR compared to group SR (P = 0.04). The change in HR was lower in incision and hemostasis periods in the group PR compared to the group SR (P < 0.001). Total intraoperative intraoperative bleeding volume and volume of blood received through drains on postoperative postoperative day 1, day 2, and in total were found to be significantly lower in group PR compared to group SR. Surgical visibility scoring was more effective in group PR compared to SR.

CONCLUSION

In the breast reduction surgery performed under esmolol-induced controlled hypotension, the effect of propofol + remifentanil anesthesia on the duration of incisional surgery, surgical visibility, and volume of surgical blood loss was more reliable and effective compared to that of sevoflurane + remifentanil, which seems to be an advantage.

Oral Bioavailability of Candesartan Cilexetil Suspension

Background:

Candesartan cilexetil is a prodrug that is converted to candesartan during absorption from the gastrointestinal tract. Candesartan is a potent, orally active, specific angiotensin II type 1 receptor antagonist that has become a well-accepted treatment for hypertension. Pediatric patients often require alternative dosage forms, as candesartan cilexetil is not yet commercially available as a liquid formulation.

Objective:

To determine the relative bioavailability of candesartan by comparing a candesartan cilexetil tablet (reference formulation) with an oral candesartan cilexetil suspension (test formulation).

Methods:

In an open-label, randomized, 2 period, 2 treatment crossover study, 24 healthy volunteers were given a 32 mg candesartan cilexetil tablet and a 32 mg candesartan cilexetil suspension with a 7 day washout period between treatments.

Results:

Pharmacokinetic analyses showed that the mean relative bioavailability of the candesartan cilexetil commercial 32 mg tablet compared with the suspension of 32 mg candesartan cilexetil was 93%. The 90% CIs of the plasma AUC for the tablet versus suspension (0.861 and 0.998, respectively) were well within the bioequivalence criteria of 80–125%. Administration of candesartan cilexetil suspension was associated with a 17% increase in the maximum plasma concentration (Cmax) relative to the tablet administration (643 vs 523 nM/L, respectively). The 90% CIs on the ratio of mean Cmaxfor the tablet and suspension were 0.738 and 0.914, respectively. Mean time to peak plasma concentrations (tmax) after suspension administration was 3.1 hours, whereas the tablet resulted in a mean tmaxof 3.9 hours. No significant differences in elimination half-life were observed between the 2 formulations. Both formulations were well tolerated, and no serious adverse events were reported.

Conclusions:

These results demonstrate that administration of candesartan cilexetil suspension achieves an extent of absorption and tolerability that is comparable with those of orally administered candesartan cilexetil tablets.

Controlled hypotension with desflurane combined with esmolol or dexmedetomidine during tympanoplasty in adults: A double-blind, randomized, controlled trial

BACKGROUND

Controlled hypotension is a technique that is used to limit intraoperative blood loss to provide the best possible surgical field during surgery.

OBJECTIVE

The aim of this double-blind, randomized, controlled study was to compare the effects of desflurane combined with esmolol or dexmedetomidine on the amount of blood in the surgical field, recovery time, and tolerability in adult patients undergoing tympanoplasty.

METHODS

Turkish patients aged 18 to 60 years, classified as American Society of Anesthesiologists physical status I or II, who were scheduled for tympanoplasty were randomly divided into 2 groups: the esmolol group or the dexmedetomidine group. After the anesthesia induction in the esmolol group, a loading dose of esmolol was infused intravenously over 1 minute at 1 mg/kg, followed by a maintenance rate of 0.4 to 0.8 mg/ kg/h. In the dexmedetomidine group, a loading dose of dexmedetomidine was infused intravenously over 10 minutes at a rate of 1 μg/kg, followed by a maintenance rate of 0.4 to 0.8 μg/kg/h. The infusion rates were then titrated to maintain mean arterial pressure (MAP) of 65 to 75 mm Hg. General anesthesia was maintained with desflurane 4% to 6%. Heart rate (HR) and MAP were recorded during anesthesia. The following 6-point scale was used to assess the amount of bleeding in the operative field: 0 = no bleeding, a virtually bloodless field; 1 = bleeding that was so mild that it was not a surgical nuisance; 2 = moderate bleeding that was a nuisance but did not interfere with accurate dissection; 3 = moderate bleeding that moderately compromised surgical dissection; 4 = bleeding that was heavy but controllable and that significantly interfered with surgical dissection; and 5 = massive bleeding that was uncontrollable and made dissection impossible. Scores ≤2 were considered to be optimal surgical conditions. The sedation score was determined at 15, 30, and 60 minutes after tracheal extubation using the following scale: 1 = anxious, agitated, or restless; 2 = cooperative, oriented, and tranquil; 3 = responsive to commands; 4 = asleep, but with brisk response to light, glabellar tap, or loud auditory stimulus; 5 = asleep, sluggish response to glabellar tap or auditory stimulus; and 6 = asleep, no response. Time to extubation and to total recovery from anesthesia (Aldrete score ≥9 on a scale of 0-10), adverse effects (eg, intraoperative hypotension [blood pressure <65 mm Hg], bradycardia [HR <50 beats/min]), intraoperative fentanyl consumption, and postoperative nausea and vomiting were recorded. Arterial blood gas analysis and kidney and liver function tests were conducted. All patients were evaluated by the same attending surgeon and anesthesiologist, both of whom were blinded to the administered study drugs.

RESULTS

Fifty-two consecutive white patients undergoing tympanoplasty were identified. Two patients had to be excluded because of hypertension and 2 refused to participate. Forty-eight patients were equally randomized to either the esmolol group (n = 24 [16 women, 8 men]; mean [SD] age, 38.4 [10.5] years) or the dexmedetomi-dine group (n = 24 [17 women, 7 men]; mean age, 35.5 [14.7] years). Sedation scores were not collected for 1 patient in the esmolol group; therefore, analysis was conducted for 23 patients. The median (range) of the scores for the amount of blood in the surgical field in the esmolol and dexmedetomidine groups was 1 (0-3) and 1 (0-2), respectively (P = NS). Mean intraoperative fentanyl consumption in the esmolol group was significantly higher than in the dexmedetomidine group (50.0 [3.0] vs 25.0 [2.5] μg/min; P = 0.002). In the esmolol group, the mean times to extubation and to recovery from anesthesia were significantly shorter than those of the dexmedetomidine group (7.0 [1.4] vs 9.1 [1.9] minutes, respectively; 5.9 [2.1] vs 7.9 [2.3] minutes; both, P = 0.001). The mean sedation scores were significantly lower in the esmolol group (n = 23, because of intent-to-treat analysis) compared with the dexmedetomidine group at 15 minutes (2.5 [0.6] vs 3.6 [0.5]; P = 0.001) and 30 minutes (2.6 [0.6] vs 3.3 [0.6]; P = 0.001) postoperatively. No significant differences were found between the study groups in regard to blood urea nitrogen or creatinine concentration, aspartate aminotransferase or alanine aminotransferase activities, pH, partial pressure of carbon dioxide, or bicarbonate, before or after the operation.

CONCLUSIONS

Both esmolol and dexmedetomidine, combined with desflurane, provided an effective and well-tolerated method of achieving controlled hypotension to limit the amount of blood in the surgical field in these adult patients undergoing tympanoplasty. Esmolol was associated with significantly shorter extubation and recovery times and significantly less postoperative sedation compared with dexmedetomidine.

Therapeutic options for the treatment of hypertension in children and adolescents

Primary hypertension in children is increasing in prevalence with many cases likely going undiagnosed. The prevalence is currently estimated at between 3%-5% in the United States and may be higher in certain ethnic groups. Primary hypertension, once felt to be rare in children, is now considered to be about five times more common than secondary hypertension. This review provides information to guide physicians through an organized approach to: 1) screening children and adolescents for hypertension during routine visits; 2) using normative percentile data for diagnosis and classification; 3) performing a clinical evaluation to identify the presence of co-morbidities; 4) initiating a plan of care including subsequent follow-up blood pressure measurements, therapeutic lifestyle changes and pharmacologic therapies.

Unintentional paediatric ingestions of angiotensin converting enzyme inhibitors and angiotensin II receptor antagonists

AIMS

There is limited information on safety of angiotensin converting enzyme (ACE) inhibitors and angiotensin II (AII) receptor antagonists in unintentional paediatric ingestions. This study was conducted with the aim of developing referral guidelines for poison information centres.

METHODS

Calls to the NSW poison information centre from January 2002 to July 2004 regarding paediatric ingestion of ACE inhibitors and AII receptor antagonists were recruited and prospectively followed up. Information collected included: demographics (age, gender, weight), type of exposure (unintentional, therapeutic error), ingested dose and clinical effects. Dose was reported in defined daily doses (DDD) to compare across and within the two drug classes with respect to the normal adult dose.

RESULTS

Nineteen cases of paediatric ingestion of ACE inhibitors and AII receptor antagonists were included. The median age was 2 years (Interquartile range (IQR): 20-33 months) and the median dose ingested was 1 DDD (IQR: 1-2). There were nine ACE inhibitor ingestions and 10 AII receptor antagonist ingestions. One of nine children (11%) observed in hospital developed transient hypotension but required no treatment and recovered without complication. This child ingested an ACE inhibitor and ingested >3 DDD.

CONCLUSION

Unintentional paediatric ingestions of ACE inhibitors and AII receptor antagonists resulted in the majority of children remaining asymptomatic. ACE inhibitor ingestions under 2 DDD can be observed at home provided the child is asymptomatic and there is a responsible adult to observe the child. The dose required for observation in AII receptor antagonist ingestions is less clear.

Pharmacokinetics of quinapril in children: assessment during substitution for chronic angiotensin-converting enzyme inhibitor treatment

Quinapril pharmacokinetics were studied in infants and children using a novel study design that allowed substitution of quinapril for one dose of the current chronic angiotensin-converting enzyme (ACE) inhibitor treatment. A total of 24 patients ranging in age from 2.5 to 82 months who were receiving an ACE inhibitor held their usual treatment on the study day and received a 0.2-mg/kg dose of quinapril syrup. Blood samples were collected through 24 hours postdose, and plasma was analyzed for quinapril and its active metabolite, quinaprilat. Quinapril was rapidly converted to quinaprilat. Quinaprilat concentrations generally peaked 1 to 2 hours postdose and declined with a mean half-life of 2.30 hours. Dosing on a mg/kg basis resulted in quinaprilat AUC and Cmax values that were generally comparable across the age range of patients in this study. The overall mean AUC0-infinity was 993 ng.h/mL (range: 533-1523), and mean Cmax was 260 ng/mL (range: 70.0-445.5). Quinaprilat CL/F correlated well with body size (body surface area or weight) and creatinine clearance (mL/min). Pharmacokinetic results after a 0.2-mg/kg dose in infants and children are comparable to those observed following a 10-mg dose in adults.

Cardiac risk factors and participation guidelines for youth sports

Accurate assessment of the cardiac system in pediatric and adolescent youth is important. The hemodynamic demands associated with exercise, training, and sport participation are usually positive and beneficial; however, when an underlying cardiac problem exists, it is imperative that such cardiac problems be identified. Safe sport-related cardiac participation guidelines should be provided for young athletes and their families and coaches. This chapter provides a physician perspective on the recognition and current cardiac management considerations for young athletes participating in both static and dynamic types of sports. The most recent guidelines for hypertension in youth are also provided.

Systemic Hypertension: Management in Children and Adolescents

Recognition of systemic hypertension in children and adolescents requires careful blood pressure measurement using proper technique to compare with appropriate normative data. Selected use of ambulatory blood pressure monitoring can identify children with "white coat" hypertension, thus avoiding unnecessary diagnostic testing and treatment in these children. Nonpharmacologic therapies including dietary sodium restriction, weight loss, and exercise may benefit children and adolescents with borderline hypertension and mild essential hypertension. These therapies may be important adjunctive agents in children requiring antihypertensive therapy as well. Historically, pharmacologic management of hypertension in children has been limited by a lack of controlled studies and age-appropriate formulations. Recent clinical trials have provided new information regarding a number of antihypertensive agents in this age group.