Current concepts in treatment of hypertensive urgencies

Management of hypertensive crises in the elderly

Hypertensive crises are elevations of blood pressure higher than 180/120 mmHg. These can be urgent or emergent, depending on the presence of end organ damage. The clinical presentation of hypertensive crises is quite variable in elderly patients, and clinicians must be suspicious of non-specific symptoms. Managing hypertensive crises in elderly patients needs meticulous knowledge of the pathophysiological changes in them, pharmacological options, pharmacokinetics of the medications used, their side effects, and their interactions with other medications. Clevidipine, nicardipine, labetalol, esmolol, and fenoldopam are among the preferred choices in the elderly due to their efficacy and tolerability. Nitroprusside, hydralazine, and nifedipine should be avoided, unless there are no other options available, due to the high risk of complications and unpredictable responses.

Aminoglycoside pharmacokinetics in African-Americans with normal renal function

OBJECTIVE

To compare aminoglycoside pharmacokinetics in African-Americans with normal renal function with published adult population values.

DESIGN

An Institutional Review Board approved concurrent study.

SETTING

The study was conducted at Howard University Hospital, Washington DC.

SUBJECTS

All subjects had serum creatinine levels of 1.5mg/dl or less and were receiving aminoglycoside for suspected or documented Gram-negative infection, had no obvious underlying disease condition that could influence aminoglycoside pharmacokinetics and were aged 18 years or older.

MAIN OUTCOME MEASURES

Volume of distribution (Vd), half-life (t1/2), elimination rate constant (Ke) and total body clearance (Cl) were calculated using a one-compartment, open, linear pharmacokinetic model. Using an unpaired Student's t-test, the pharmacokinetic values of our patients were compared with general population values.

INTERVENTIONS

Patients receiving aminoglycosides were identified by the pharmacist through the hospital's standard antibiotic order sheet. Twenty-five patients were enrolled after they met the inclusion criteria. Pharmacists made recommendations for dose change as part of standard of care when inappropriate doses were ordered. In collaboration with medical and nursing staff, the amount and time of dose administration, and steady-state peak and trough serum drug levels were stringently measured, documented on a data collection form and used to calculate pharmacokinetic values for our patients. The form was also used to document demographic information.

RESULTS

The following values were obtained: Vd 0.27+/-0.15 litres/kg, t(1/2) 1.93+/-1.38h, Ke 0.31+/-0.134/h (gentamicin), Ke 0.22 +/- 0.10/h (tobramycin), Cl 103.95+/-62.98ml/kg/h (gentamicin) and Cl 118.96+/-84.83ml/kg/h (tobramycin). These values are not significantly different from general population values. Following a mean tobramycin or gentamicin dose of 1.32+/-0.32mg/kg ideal body weight (IBW)/ dose or 1.11+/-0.33 mg/kg actual body weight (ABW)/ dose every 8h, patients achieved a mean peak and trough serum drug levels of 6.6+/-3.86mg/litre and 1.03+/-0.68mg/litre, respectively. Wide interpatient pharmacokinetic variability was also observed.

CONCLUSIONS

We conclude that aminoglycoside pharmacokinetics in African-Americans seem to be consistent with the published general population values. Thus, initiating aminoglycoside regimens using population dosing guidelines appears to be appropriate. However, due to the observed wide interpatient pharmacokinetic variability, individualized dosing is required with very close monitoring, to avoid or minimize toxicity.

Treatment of hypertensive urgencies with oral nifedipine, nicardipine, and captopril

Sixty-five patients with uncomplicated hypertensive urgencies were treated in the emergency and cardiology departments with 20 mg nifedipine, 20 mg nicardipine, or 25 mg captopril in a randomized study. The study population consisted of 65 patients ranging in age from forty-one to seventy-one. Blood pressure and heart rate were assessed for six hours after intake of the antihypertensive agents. Within sixty minutes nifedipine reduced blood pressure by an average of 74.7 mmHg for the systolic and 35.4 mmHg for the diastolic. Average heart rate increased significantly by 11.6 beats/min at within thirty minutes. Nicardipine and captopril produced equivalent falls in systolic (-81.6 and -79.4 mmHg) and diastolic (-37.3 and -33 mmHg) blood pressure respectively, but did not increase heart rate significantly. The antihypertensive effect of each drug was maintained until six hours after medication. In conclusion, nifedipine, nicardipine, and captopril show similar efficacy in the treatment of hypertensive urgencies. The authors believe that these drugs can be used as first-line therapy in the treatment of hypertensive urgencies safely and effectively.

Dose-response evaluation of oral labetalol in patients presenting to the emergency department with accelerated hypertension

STUDY OBJECTIVE

Dose-response evaluation of oral labetalol (100, 200, or 300 mg) on heart rate and systemic blood pressure in emergency department patients with hypertensive urgency (diastolic blood pressure, 110 to 140 mm Hg, and no end-organ evidence of hypertensive emergency).

METHODS

This acute-treatment, dose-ranging study used a randomized, double-blind, parallel design. Patients with supine diastolic blood pressure of 110 to 140 mm Hg after 30 minutes of bedrest received an oral dose of labetalol. Supine blood pressure and heart rate were measured manually and recorded hourly for four hours after dose. Diastolic blood pressure of 100 mm Hg or less or a 30-mm Hg reduction in diastolic blood pressure was considered a treatment success.

RESULTS

Two hundred fifty-five patients were evaluated for inclusion, and 36 patients (19 women and 17 men; mean age, 44 years; age range, 23 to 67 years) were studied. The most frequent reason for exclusion was a spontaneous decrease in diastolic blood pressure to less than 110 mm Hg (31%) with bedrest. There were 12 patients in each treatment group. Compared with baseline, the 100-mg dose significantly (P less than .05) reduced heart rate at three and four hours after dose, and the 300-mg dose significantly (P less than .05) reduced heart rate at one, two, and three hours after dose; the 200-mg dose did not significantly affect heart rate. All doses produced a significant decrease in systolic and diastolic blood pressures at one, two, three, and four hours after dose compared with baseline. There were no statistically significant differences between treatment groups with regard to systolic or diastolic blood pressure or heart rate at baseline or one, two, three, or four hours after dose. At two hours after dose, diastolic blood pressure control was observed in 75%, 58%, and 67% of patients receiving 100, 200, and 300 mg, respectively (P = .903). At four hours after dose, diastolic blood pressure control was observed in 50%, 64%, and 67% of patients receiving 100, 200, and 300 mg, respectively (P = .755). A comparison of treatment success rates between the two time periods showed a waning of response with the 100-mg dose of labetalol at hour 4 compared with hour 2 (P less than .05). No adverse effects were observed.

CONCLUSION

Labetalol provides safe and effective treatment for hypertensive urgencies when administered orally in doses of 100 to 300 mg.

Evaluation of drug therapy for treatment of hypertensive urgencies in the emergency department

Oral nifedipine (N) and clonidine (C) are often used in the treatment of hypertensive urgencies; however, until recently, there were no comparative studies using the same patient population. The authors reviewed the records of hypertensive patients treated in the emergency department between October 1, 1987 and September 30, 1988. Selected patients had a diastolic blood pressure (DBP) of greater than 115 mm Hg without evidence of acute end organ damage. Patients were stratified into three treatment groups: N, C, and group 3 (G3). G3 received a variety of drug therapies but not exclusively N or C. Systolic blood pressure (SBP), DBP, mean arterial pressure (MAP), percent decrease in MAP (%MAP), time to lower blood pressure, admissions, and discharges were evaluated. Efficacy and safety were defined as reaching a DBP less than 110 mm Hg but %MAP of no greater than either 25% or 40%, respectively. Thirty-five N, 32 C, and 27 G3 patients were identified with no statistical difference between groups in race, gender, pretreatment SBP, DBP, or MAP. N, C, and G3 significantly reduced SBP, DBP, and MAP (P less than .01). Comparing N, C, and G3, no differences were observed in %MAP, admissions, discharges, efficacy, or safety. Time required to decrease blood pressure differed between all three groups (44 +/- 32 N v 77 +/- 57 C v 152 +/- 94 min G3) (p less than .05). These results indicate that N, C, and a variety of drug therapies are equally effective and safe in the treatment of hypertensive urgencies.

Cerebrovascular aspects of antihypertensive treatment

Although the treatment of hypertension clearly benefits the brain in most patients, there are, however, unfortunate exceptions. Overzealous blood pressure lowering especially, and sometimes conservative blood pressure lowering, occasionally compromise the supply of blood to the brain to such an extent that neurological dysfunction or death results. Despite an awareness of this problem for more than a decade, the number of reports of such cases is increasing. An understanding of the problem requires detailed knowledge of both the pathophysiology of the cerebral circulation in hypertension and the cerebrovascular effects of antihypertensive drugs. If antihypertensive treatment, in particular emergency blood pressure lowering, is to always be safe, thought must be given to the cerebrovascular effects of the drugs to be used. This topic is discussed in relation to the observed (i.e., experimentally determined) and inferred (i.e., from clinical observation) effects of antihypertensive drugs and treatment on the cerebral circulation, especially with regard to autoregulation of cerebral blood flow.

Subcutaneous administration of nifedipine

Contents of a 10 mg nifedipine capsule (0.33 ml) were withdrawn by syringe and administered subcutaneously to a patient with hypertensive urgency due to misinterpretation of a physician's order. The drug apparently had its desired hypotensive effect and no adverse effects were noted. The literature on use of nifedipine in hypertensive urgency is reviewed. Subcutaneous administration is not recommended because of a lack of suitable controlled studies and the potential for adverse effects.