The therapy of Cushing's disease in adults and children: an update

Cushing's disease (CD) is a rare endocrine disorder resulting from excessive production of adrenocorticotrophin hormone by a pituitary adenoma. The consequent hypercortisolaemia gives rise to characteristic features of the disease and its morbidities. Treatments aim to restore normal cortisol levels, provide long-term control of the disease and the tumour, and the improvement of patient well-being. The first line of treatment remains transsphenoidal surgery with remission rates of 65-90% in CD secondary to a pituitary microadenoma. Second-line treatment includes repeat surgery, radiotherapy, medical therapy, and bilateral adrenalectomy. The success rate of radiotherapy ranges from 46% to 74% and is probably independent of the mode of delivery of the radiation, but may take several years to become effective. Medical therapy is useful in acutely unwell patients or while awaiting radiotherapy to become effective. The most often-used medical agents include metyrapone and ketoconazole, which inhibit steroidogenesis; less often, centrally-acting drugs or a glucocorticoid receptor blocker are used, but experience with them is more limited. Bilateral adrenalectomy remains an important treatment option to control unresponsive severe hypercortisolism, particularly in patients with severe CD.The management of childhood CD does not differ from adult disease, with transsphenoidal surgery as successful as in adults but radiotherapy is more rapid in onset. Regardless of the age of the patient, Cushing's disease remains a challenge to the physician and requires a multidisciplinary approach to achieve the most desirable outcome.

α1-Adrenergic Receptor Antagonists and the Iris: New Mechanistic Insights into Floppy Iris Syndrome

Understanding the role of adrenergic receptors in iris biology has gained widespread interest due to the recently described intraoperative floppy iris syndrome sometimes encountered during cataract surgery. alpha(1)AR-mediated iris dilator smooth muscle contraction occurs via alpha(1a)ARs whereas alpha(1b)ARs mediate iris arteriolar contraction. Because alpha(1)AR antagonists are first-line therapy for benign prostatic hyperplasia and lower urinary tract symptoms, more elderly patients requiring cataract surgery now receive these drugs. After reviewing intraoperative floppy iris syndrome, strengths/weaknesses of supporting data, and reviewing iris biology, a case is made that rather than being drug specific (alpha(1)AR antagonists), intraoperative floppy iris syndrome may represent the "tip of the iceberg." Relaxed iris dilator muscle resistant to adrenergic agonists should be expected with clinical drugs shown to relax the iris dilator (e.g., antagonists at alpha(1)AR, endothelin-A, angiotensin receptors, nitric oxide donors such as nitrates), and/or diseases associated with endothelial dysregulation (e.g., congestive heart failure, diabetes, hypertension). Rather than a rare, unexpected, unpredictable syndrome due to one drug, a careful medical history should elucidate intraoperative floppy iris syndrome predisposition. Just as anticoagulants are discontinued prior to elective surgery, conservative management of elderly patients suggests discontinuation of drugs that relax iris dilator muscle, in consultation with the patient's primary physician, should be considered prior to cataract surgery.

[Neurological manifestations in critically ill patients]

AIMS

To describe the pathophysiology, diagnosis and clinical manifestations of the neurological complications that critically ill patients often develop in intensive care units, and to discuss their treatment and prognosis, in the light of the most significant contemporary literature.

DEVELOPMENT

The most frequent complication suffered by critically ill patients is sepsis, with encephalopathy as the main manifestation, and this has a direct effect on their prognosis. Polyneuropathy of the critically ill patient is linked to sepsis, as the main precipitating factor, as well as to the presence of high levels of glucose, which plays an important role in deciding whether mechanical ventilation can be withdrawn or not. Myopathy of the critically ill patient is related to the use of fluorinated steroids and neuromuscular blockers, which are frequently administered to these patients. All these entities represent a significant diagnostic challenge for the physician and are accompanied by important sequelae that continue after the patient's discharge from hospital, as well as myopathies and neuropathies associated to the use of drugs that are commonly administered to critically ill patients. It is therefore necessary to be familiar with the pathophysiology of the damage and with the associated factors, if a suitable diagnostic approach is to be employed.

CONCLUSIONS

The incidence of these pathologies and their complications makes them important conditions that require a swift, accurate diagnosis so that treatment can be established early on and a prognosis can also be determined.

Effects of ??1-Adrenoceptor Antagonists on Male Sexual Function

alpha(1)-Adrenoceptor antagonists such as alfuzosin, doxazosin, tamsulosin and terazosin are first-line agents for the treatment of lower urinary tract symptoms suggestive of benign prostatic hyperplasia (BPH), but are only second-line agents (doxazosin and terazosin only) for the treatment of arterial hypertension. Sexual function is complex and includes multiple domains such as sexual desire (libido), erectile function and ejaculatory function. Erectile and ejaculatory functions are frequently reduced in patients with BPH and can impact on their quality of life. Therefore, the treatment of BPH should aim to maintain or even restore sexual function.alpha(1)-Adrenoceptor antagonists lack major effects on sexual desire in placebo-controlled studies. Reports on erectile function are inconsistent, with both beneficial and adverse effects being reported, but impotence can occur in some patients without clear differences between drugs. Ejaculatory dysfunction during treatment may represent (relative) an ejaculation. It occurs more frequently with tamsulosin than with other drugs of this class, but the differences are not big enough to be consistently detectable in directly comparative studies. We propose that such differences between drugs should be weighed against differences in cardiovascular tolerability when choosing the optimal treatment for each patient.

Evaluation of Carvedilol for the Treatment of Portal Hypertension

Development of bleeding gastroesophageal varices is a serious consequence of portal hypertension secondary to cirrhosis. Nonselective beta-blockers have been used to reduce portal pressures and prevent primary and secondary bleeding episodes. However, up to two thirds of patients may not respond appropriately to these agents. Nonselective beta-blockers combined with vasodilatory drugs result in enhanced lowering of portal pressures by targeting several mechanisms involved in this process. Unfortunately, this practice is associated with increased adverse effects, such as hypotension, and minimal reductions in mortality. Carvedilol possesses both nonselective beta-antagonist and alpha1-receptor antagonist activity. Given its combined mechanism of action, carvedilol presents a potential option for lowering portal pressures. Its effects on lowering portal pressures and its role in therapy are undefined. Using MEDLINE (1966-2003) and International Pharmaceutical Abstracts (1970-2003), the English-language literature was searched to identify human studies assessing carvedilol's effects on lowering portal pressure. In general, carvedilol therapy was associated with mean reductions of 16-43% in portal pressure, assessed by the hepatic venous pressure gradient (HVPG) after single and multiple doses. Studies comparing carvedilol with propranolol revealed equal or enhanced efficacy in lowering HVPG. Large percentages of patients had significant HVPG reductions to levels that prevent variceal bleeding. Carvedilol also was associated with substantial symptomatic hypotension, especially in patients with ascites or Child-Pugh class B or C cirrhosis. Efficacy and adverse effects generally seem to be dose related. Carvedilol appears to be a potentially viable option for treating portal hypertension. Further multiple-dose trials comparing carvedilol with standard therapy are needed to assess the agent's long-term safety and effectiveness in preventing variceal bleeding.

Labetalol-induced hepatitis in a patient with chronic hepatitis B infection

Drug-induced hepatotoxicity is an important cause of hepatocellular injury. Hepatic necrosis may range from asymptomatic elevations in transaminases to fulminant hepatic failure and death. A 50-year-old Asian man developed moderate elevations of hepatic transaminases after commencing labetalol therapy for a hypertensive cerebral hemorrhage. Extensive evaluation revealed evidence of chronic hepatitis B infection, of which the patient was previously not aware. Hepatic transaminases normalized after discontinuation of labetalol.

Race and the response to adrenergic blockade with carvedilol in patients with chronic heart failure

BACKGROUND

The benefits of angiotensin-converting-enzyme inhibitors and beta-blockers may be smaller in black patients than in patients of other races, but it is unknown whether race influences the response to carvedilol in patients with chronic heart failure.

METHODS

In the U.S. Carvedilol Heart Failure Trials Program, 217 black and 877 nonblack patients (in New York Heart Association class II, III, or IV and with a left ventricular ejection fraction of no more than 0.35) were randomly assigned to receive placebo or carvedilol (at doses of 6.25 to 50 mg twice daily) for up to 15 months. The effects of carvedilol on ejection fraction, clinical status, and major clinical events were retrospectively compared between black and nonblack patients.

RESULTS

As compared with placebo, carvedilol lowered the risk of death from any cause or hospitalization for any reason by 48 percent in black patients and by 30 percent in nonblack patients. Carvedilol reduced the risk of worsening heart failure (heart failure leading to death, hospitalization, or a sustained increase in medication) by 54 percent in black patients and by 51 percent in nonblack patients. The ratios of the relative risks associated with carvedilol for these two outcome variables in black as compared with nonblack patients were 0.74 (95 percent confidence interval, 0.42 to 1.34) and 0.94 (95 percent confidence interval, 0.43 to 2.05), respectively. Carvedilol also improved functional class, ejection fraction, and the patients' and physicians' global assessments in both the black patients and the nonblack patients. For all these measures of outcome and clinical status, carvedilol was superior to placebo within each racial cohort (P<0.05 in all analyses), and there was no significant interaction between race and treatment (P> 0.05 in all analyses).

CONCLUSIONS

The benefit of carvedilol was apparent and of similar magnitude in both black and nonblack patients with heart failure.

Carvedilol for prevention of restenosis after directional coronary atherectomy : final results of the European carvedilol atherectomy restenosis (EUROCARE) trial

BACKGROUND

In addition to its known properties as a competitive, nonselective beta and alpha-1 receptor blocker, carvedilol directly inhibits vascular myocyte migration and proliferation and exerts antioxidant effects that are considerably greater than those of vitamin E or probucol. This provides the basis for an evaluation of carvedilol for the prevention of coronary restenosis.

METHODS AND RESULTS

In a prospective, double-blind, randomized, placebo-controlled trial, 25 mg of carvedilol was given twice daily, starting 24 hours before scheduled directional coronary atherectomy and continuing for 5 months after a successful procedure. The primary end point was the minimal luminal diameter as determined during follow-up angiography 26+/-2 weeks after the procedure. Of 406 randomized patients, 377 underwent attempted atherectomy, and in 324 (88.9%), a </=50% diameter stenosis was achieved without the use of a stent. Evaluable follow-up angiography was available in 292 eligible patients (90%). No differences in minimal luminal diameter (1.99+/-0.73 mm versus 2.00+/-0.74 mm), angiographic restenosis rate (23.4% versus 23.9%), target lesion revascularization (16.2 versus 14.5), or event-free survival (79.2% versus 79.7%) between the placebo and carvedilol groups were observed at 7 months.

CONCLUSIONS

The maximum recommended daily dose of the antioxidant and beta-blocker carvedilol failed to reduce restenosis after successful atherectomy. These findings are in contrast to those of the Multivitamins and Probucol Trial, which raises doubts regarding the validity of the interpretation that restenosis reduction by probucol was via antioxidant effects. The relationship between antioxidant agents and restenosis remains to be elucidated.

Clinical pharmacology of alpha1-adrenoceptor antagonists

Benign prostatic hyperplasia (BPH) is the most prevalent condition to affect men beyong middle age. alpha1-adrenoceptor blockers have been used in the treatment of BPH for more than 20 years and their effect on the lower urinary tract is now well established. These agents as a class have produced consistent improvements in both symptom scores and urinary flow rates in around 60-70% of patients treated. This efficacy is balanced against a small, but significant, incidence of side-effects, that consist of headaches, dizziness, nasal stuffiness, tiredness and very occasionally postural hypotension. There are important other effects of alpha1-adrenoceptor blockers; for example in men with hypertension, these agents generally produce a clinically significant reduction in both systolic and diastolic blood pressures. There is also well documented evidence of a reduction in LDL cholesterol levels as well as serum triglycerides. A new and interesting observation is that patients receiving certain alpha1-adrenoceptor blockers notice improvement in their sexual function and in particular in the quality of their erectile response. This effect has been attributed to decreased sympathetic vasoconstrictor tone to the helicine arteries supplying the lacunar spaces of the corpora cavernosa in the penis. In summary alpha1-adrenoceptor blockers produce significant improvements in symptoms and flow rates in patients with bladder outflow obstruction due to benign prostatic hyperplasia. This is balanced against a small but significant incidence of side-effects, but some of these side-effects, such as a reduction in blood pressure in hypertensive patients, improvement in lipid profile and improvement in erectile function could be construed as beneficial.

Antiadrenergic effect of chronic amiodarone therapy in human heart failure

OBJECTIVES

The aim of the present study was to evaluate the influence of amiodarone on neurochemical parameters of sympathetic nervous activity in patients with congestive heart failure.

BACKGROUND

Unlike most antiarrhythmic agents, amiodarone has been shown to exert a beneficial effect on survival in some studies of patients with congestive heart failure. The pharmacology of this agent is complex, and as such, the mode of its action is unclear in humans. Some experimental studies suggest that amiodarone exerts a sympatholytic effect.

METHODS

To evaluate the effect of amiodarone on sympathetic nervous activity, we measured the total systemic and cardiac norepinephrine (NE) spillover rate by isotope dilution in 58 patients with severe heart failure (left ventricular ejection fraction 20 +/- 1%), 22 of whom were receiving chronic amiodarone treatment. Release rates for dihydroxyphenylalanine (DOPA, a precursor of NE), and endogenous and radiolabeled dihydroxyphenylglycol (DHPG and 3H-DHPG, intraneuronal metabolites of NE and 3H-NE, respectively) were also determined to assess sympathetic neuronal integrity.

RESULTS

Amiodarone-treated patients had significantly lower cardiac spillover rates for NE (42%, p = 0.001), DOPA (74%, p < 0.001), DHPG (44%, p < 0.01) and 3H-DHPG (51%, p < 0.01) than those patients not treated with amiodarone. Hemodynamic assessment of amiodarone-treated patients revealed higher cardiac output (4.4 +/- 0.2 vs. 3.7 +/- 0.2 liters/min, p < 0.01), and slightly lower pulmonary capillary wedge pressure (18 +/- 2 vs. 22 +/- 1, p = NS) than in untreated patients. After correction for the potential confounding effect of hemodynamic differences, amiodarone-treated patients continued to demonstrate significantly lower spillover rates of NE, DOPA and DHPG from the heart.

CONCLUSIONS

These data indicate that amiodarone may exert beneficial effects on the failing human heart through a sympatholytic process, and this action appears to be relatively cardioselective.

Drug-induced attack of bronchial asthma in inpatients: a 20-year survey of the Comprehensive Hospital Drug Monitoring Programme on adverse drug reactions, Berne/St. Gallen

Epidemiological aspects of attacks of bronchial asthma related to drugs are prospectively studied in inpatients of three teaching hospitals in the Comprehensive Hospital Drug Monitoring (CHDM)-programme. Results are based on 34,840 individual patients (among 48,005 consecutive admissions) in the years 1974-1993. Between 1974 and 1993, every patient admitted to any of the three medical clinics in the CHDM programme was monitored for any suspicion of an adverse drug reaction (ADR); every drug exposure period during hospital stay was registered. Nineteen patients (0.05% of the 34,840 individual patients) had at least one attack of bronchial obstruction during hospitalisation, considered as probable or definite ADR. The frequency related to exposure periods in response to penicillins is 0.014%, to non-steroidal anti-inflammatories (NSAIDs) 0.0145, to acetyl salicylic acid (ASA) 0.018%, to paracetamol 0.008% and to beta-adrenoceptor blockers 0.26%. Of the 12 patients reacting to a drug with an allergic or idiosyncrasy/intolerance type of bronchial obstruction, 7 had a history of bronchial asthma (extrinsic or intrinsic), and 3 had the diagnosis chronic obstructive pulmonary disease (COPD). A history of bronchial asthma or COPD is confirmed to be a risk factor for this particular ADR. Of the seven patients with a bronchial obstruction to beta-adrenoceptor blockers, five were diagnosed with COPD, while two had neither COPD nor bronchial asthma. The relative risk for this pharmacological reaction in COPD patients was 96 (95% confidence interval 45-208) compared with non-COPD patients in the group of 3244 exposed to beta-adrenoceptor blockers.