[Effect of selective alpha1 receptor agonist in the treatment of children with postural orthostatic tachycardia syndrome]

OBJECTIVE

The study was designed to examine the effect of selective alpha1 receptor agonist midodrine hydrochloride in the treatment of children with postural orthostatic tachycardia syndrome.

METHODS

Fifty-five children (23 male, 32 female, age 5 - 19 yrs, mean age 12.3 +/- 3.1 yrs) who came from Peking University First Hospital were included in the study and clinical investigations as well as standing test, basic head-up tilt test and sublingual nitroglycerin-provocated head-up tilt test under quiet circumstance were conducted. They were randomly divided into treatment group (with midodrine hydrochloride and oral rehydration salt treatment) and control group (with oral rehydration salt treatment only). At last, the disease-free rate, improvement rate and effective rate of symptoms, and the rate of HUT from positive to negative response were compared between control group and treatment group. SPSS 10.0 software was used for the statistical analysis of these data.

RESULTS

The symptom improvement rate in treatment group was significantly higher than that of control group after three and six weeks of treatment (100.0% vs. 42.4%, P < 0.001; 100.0% vs. 42.4%, chi2 = 19.352, P < 0.001). The disease-free rate at follow-up end-point in treatment group was significantly higher than that of control group (77.3% vs. 27.3%, chi2 = 13.239, P < 0.001). The effective rate at follow-up end-point in treatment group was also significantly higher than that of control group (100.0% vs. 36.4%, chi2 = 22.647, P < 0.001). The rate of HUT changing from positive to negative response between two groups after three weeks of treatment was not significantly different (31.8% vs. 12.1%, P > 0.05), but it was significantly different (81.0% vs. 48.5%, P < 0.05) after six weeks of treatment.

CONCLUSION

Selective alpha1 receptor agonist midodrine hydrochloride is effective in the treatment of children with postural orthostatic tachycardia syndrome.

Correction of severe hypotension by oral pseudoephedrine in a patient with idiopathic autonomic dysfunction

The purpose of this case study was to review the use of an oral alpha-adrenergic agent to correct severe vasopressor-dependent hypotension in a patient with idiopathic autonomic dysfunction. Autonomic dysfunction resulting in severe hypotension that requires intravenous vasopressors can present challenges in the treatment of critically ill patients. Most patients are weaned from intravenous vasopressor agents once severe sepsis has resolved. Because of worsening idiopathic autonomic dysfunction during recovery from sepsis, this 76-year-old woman required prolonged care in the intensive care unit. Oral alpha-adrenergic agonist therapy in the form of pseudoephedrine proved to be a valuable treatment option to wean this patient off the vasopressor dependence and allow for placement in a long-term care facility.

[Usefulness of bilateral sympathectomy using video-assisted thorascopic surgery in the treatment of essential hyperhidrosis]

Essential, idiopathic, or primary hyperhidrosis is defined as excessive sweating in certain areas of the body due to factors unrelated to other disease. Clinical presentation can be categorized as palmar, plantar, axillary, or craniofacial. Medical treatment (aluminium salts, iontophoresis, anticholinergic drugs, and alpha2-agonists) is of questionable effectiveness. Intradermal injections of botulinum toxin are very effective for the treatment of axillary hyperhidrosis. Surgical treatment involves resection (sympathectomy) or electrocautery (sympathicolysis) of the thoracic sympathetic chain, or compression of the sympathetic chain with clips, in all cases via video-assisted thorascopic surgery. One or more ganglia between T2 and T5 are usually resected depending on the area affected by hyperhidrosis: T2 for craniofacial hyperhidrosis, T3 and T4 for palmar hyperhidrosis, and T3 to T5 for combined palmar and axillary hyperhidrosis. The technique is very useful and is effective in those patients with primary hyperhidrosis who have not responded to conservative treatment.

Pulmonary circulatory effects of norepinephrine in newborn infants with persistent pulmonary hypertension

OBJECTIVE

To evaluate the respiratory and the pulmonary circulatory effects of norepinephrine in newborn infants with persistent pulmonary hypertension (PPHN)-induced cardiac dysfunction.

STUDY DESIGN

Inclusion criteria were: 1) Newborn infants >35 weeks gestational age; 2) PPHN treated with inhaled nitric oxide; and 3) symptoms of circulatory failure despite adequate fluid resuscitation. Lung function and pulmonary hemodynamic variables assessed with Doppler echocardiography were recorded prospectively before and after starting norepinephrine.

RESULTS

Eighteen newborns were included (gestational age: 37 +/- 3 weeks; birth weight: 2800 +/- 700 g). After starting norepinephrine, systemic pressure and left ventricular output increased respectively from 33 +/- 4 mm Hg to 49 +/- 4 mm Hg and from 172 +/- 79 mL/kg/min to 209+/-90 mL/kg/min (P < .05). Although the mechanical ventilatory variables have not been changed, the post-ductal transcutaneous arterial oxygen saturation increased from 89% +/- 1% to 95% +/- 4%, whereas the oxygen need decreased from 51% +/- 24% to 41% +/- 20% (P < .05). The pulmonary/systemic pressure ratio decreased from 0.98 +/- 0.1 to 0.87 +/- 0.1 (P < .05). Mean left pulmonary artery blood flow velocity increased by 20% (P < .05).

CONCLUSION

Norepinephrine may improve lung function in newborn infants with PPHN through a decrease in pulmonary/systemic artery pressure ratio and improved cardiac performance.

Comparison of allergy rates in glaucoma patients receiving brimonidine 0.2% monotherapy versus fixed-combination brimonidine 0.2%-timolol 0.5% therapy

OBJECTIVE

To evaluate the incidence of ocular allergy in glaucoma patients prospectively treated with 0.2% brimonidine-0.5% timolol fixed combination (Combigan) compared with the incidence of ocular allergy in patients treated with 0.2% brimonidine (Alphagan) monotherapy.

STUDY DESIGN AND METHODS

This was a comparative, non-randomized, single-site, interventional study involving patients with primary open-angle glaucoma or exfoliation syndrome who had not previously used brimonidine in any formulation and had no history of ocular allergy. In one study arm, 102 patients were prospectively treated with twice-daily 0.2% brimonidine-0.5% timolol fixed combination. In the other study arm, medical charts at the same center were reviewed to identify a control group of 102 patients who had been treated with twice-daily 0.2% brimonidine monotherapy. Follow-up was at 1, 3, 6, 9, 12, 15, and 18 months of treatment.

MAIN OUTCOME MEASURE

Ocular allergy defined as the presence of follicles and redness severe enough to warrant discontinuation of the medication.

RESULTS

The incidence of ocular allergy over 18 months of treatment was 8.8% (9/102) in the fixed-combination group compared with 17.6% (18/102) in the brimonidine group (p=0.097). Kaplan-Meier survival analysis suggested that ocular allergy may be reduced or delayed in patients treated with the brimonidine-timolol fixed combination (p=0.066).

CONCLUSIONS

The brimonidine-timolol fixed combination was associated with a 50% lower incidence in ocular allergy compared with 0.2% brimonidine monotherapy. This difference between treatments was not statistically significant (p=0.097) but is likely to be clinically important. Additional studies are needed to evaluate the incidence of ocular allergy associated with brimonidine-timolol fixed combination treatment.

Respiratory, metabolic and hemodynamic effects of clonidine in ventilated patients presenting with withdrawal syndrome

OBJECTIVE

To investigate the respiratory, metabolic and hemodynamic effects of clonidine in ventilated patients presenting with withdrawal syndrome after sedation interruption.

DESIGN

Prospective, interventional, single-center study in 30 ventilated ICU patients.

INTERVENTIONS

Metabolic [oxygen consumption (VO(2)), CO(2) production (VCO(2)), resting energy expenditure (REE)], respiratory [minute ventilation (V (E)), tidal volume (V (T)), respiratory rate (RR)] and hemodynamic (HR, SAP, MAP) parameters were measured in 30 ventilated ICU patients. Measurements were performed first under sedation with remifentanil-propofol, then after sedation interruption, and finally after clonidine administration (0.9-1.8 mg of clonidine in two doses of 10 min interval).

RESULTS

Sedation interruption produced significant increases in the hemodynamic parameters (SAP and MAP by 33%, HR by 37%), and metabolic rate (increase in VO(2) by 70%, VCO(2) by 88% and REE by 74%), leading to high respiratory demands (increase in V (E) from 9 to 15 l/min). The V (E) was increased due to a twofold increase in the RR; V (T) remained constant. In 25 out of 30 patients, clonidine administration decreased the hemodynamic (SAP, MAP and HR), metabolic (VO(2), VCO(2), REE) and respiratory parameters to values close to those observed with sedation. Clonidine induced mild sedation and patients became more cooperative with the ventilator. All patients responding to clonidine were weaned from the ventilator in 2 days (median, range 1-18 days).

CONCLUSION

Patients with withdrawal syndrome had significantly elevated hemodynamic, metabolic and respiratory demands. Clonidine significantly decreased these demands, induced mild sedation and facilitated patient cooperation with the ventilator, enabling ventilator weaning.

Treating vasomotor symptoms of menopause: the nurse practitioner's perspective

PURPOSE

This article reviews the pathophysiology of vasomotor symptoms (VMS) of menopause and current management options.

DATA SOURCES

Current scientific literature.

CONCLUSIONS

In most menopausal women, loss of ovarian function results in VMS, including hot flashes, night sweats, and mood and sleep disturbances. Hormone therapy (HT) has been the mainstay of VMS treatment for many years, but safety concerns raised by publication of the Women's Health Initiative (WHI) results have dramatically reduced the use of this treatment. Since the WHI published its findings, attention has focused on other novel treatments for menopausal symptoms, including low-dose oral or transdermal HT and agents such as selective serotonin reuptake inhibitors, serotonin-norepinephrine reuptake inhibitors, gabapentin, and clonidine. Many women also use complementary and alternative medications to manage VMS, but little evidence from controlled clinical trials supports their efficacy.

IMPLICATIONS FOR PRACTICE

The increasing number of alternative treatments for VMS requires improvement in patient-provider communication about treatment risks and benefits, individualization of treatment to meet patient needs and attitudes, and careful follow-up to ensure adherence to potentially effective therapy. Nurse practitioners play a leading role in patient evaluation, discussions, and management to help women achieve control over bothersome VMS that dramatically impact their quality of life.

Medications for adolescents with attention-deficit/hyperactivity disorder

ADHD is recognized as a neurologic condition rather than just bad behavior. Medical treatment has been recognized as very helpful. Risks of untreated ADHD are substantial. Every life area is negatively affected including school performance, drug abuse and dependence risk, driving performance, sexually transmitted diseases, unwanted pregnancy and family cohesiveness to mention some of them. Frequent misinformation in the popular media causes apprehension about medical treatment. Even after almost 60 years stimulants remain the mainstay in treatment of ADHD. Newer release systems have produced longer acting and smoother acting medication. Side effects have always been brief and mild however, newer forms cause fewer side effects than older preparations and cover symptoms for more of the waking hours of each day. Although studies in adolescents are less numerous than in children the literature standard supports the safety and efficacy of stimulants in adolescents. In addition there are non-stimulant medications that have shown efficacy in adolescents. There are now a greater number of medications and more effective medications than ever before. Clinical pearls in medication management are shared in practical terms so that these newer treatments can be used to help those affected with ADHD more effectively than ever before.

Emerging treatments for Tourette's disorder

Tourette's disorder is a childhood-onset neuropsychiatric disorder characterized by multiple motor and vocal tics. Many children with Tourette's disorder improve throughout adolescence. However, some adults with Tourette's disorder still experience severe symptoms and significant disability. This article examines the evidence base for current treatments for Tourette's disorder. Emerging treatments such as deep brain stimulation, habit reversal therapy, and repetitive trans-cranial magnetic stimulation are also discussed.

Levetiracetam in the treatment of antipsychotics-resistant Tourette syndrome

Levetiracetam, an anti-epileptic agent that enhances GABAergic neurotransmission, is one of the newest alternative treatments of Tourette syndrome (TS). We present the case of a 23-year-old female patient suffering from TS since the age of 7, who exhibited poor response to a variety of agents (haloperidol, pimozide, clonidine and various adjunctive agents) and had four hospitalizations during the previous 2 years due to the deterioration of her clinical state. On her last admission, in addition to clonidine 600 microg/day (already part of her regimen for the previous 4 years), levetiracetam was prescribed, up to 2000 mg/day, progressively titrated over a 3-week period. The patient presented a significant improvement on her TS symptomatology (the score on the Yale Global Tic Severity Scale dropped from 70 at admission, to 25 five weeks later, at discharge), which was preserved during the subsequent 4 months, without any serious side-effect.

Noradrenergic dysfunction and the psychopharmacology of posttraumatic stress disorder

The catecholamine norepinephrine is a critical effector of the mammalian stress response and has been implicated in the pathophysiology of posttraumatic stress disorder (PTSD)-a syndrome intrinsically related to the experience of extraordinary stress. Symptom-linked hypernoradrenergic derangements have been observed in PTSD and several studies have examined the potential therapeutic effects of agents that dampen the centrally hyperactive noradrenergic state. These agents include compounds that decrease norepinephrine release (e.g. centrally acting alpha(2) agonists such as clonidine) and those which block post-synaptic norepinephrine receptors (e.g. centrally acting alpha(1) or beta receptor antagonists such as prazosin or propranolol). In this article, we review studies of central noreadrenergic hyperactivity under both basal and challenge conditions and explore the evidence for these derangements as potential psychopharmacologic targets in patients with PTSD. Given the significant involvement of CNS norepinephrine hyperactivity in PTSD, and its link to intrusive and hyperarousal symptoms, it is not surprising that interventions directed at this system have therapeutic potential in PTSD. The utility of these anti-adrenergics in the clinical treatment of PTSD remains to be determined, though it is possible that they may prove to have primary roles in a disorder that is only modestly responsive to antidepressant treatment.

Dexmedetomidine for the treatment of paroxysmal autonomic instability with dystonia

INTRODUCTION

A 38-year-old man with severe head trauma complicated by paroxysmal severe intracranial pressure elevation associated with tachypnea, tachycardia, diaphoresis, and extensor posturing was diagnosed as suffering from paroxysmal autonomic instability with dystonia (PAID). These events were unresponsive to standard medical therapy, which included morphine, fentanyl, labetalol, lorazepam, metoprolol, and clonidine.

METHODS

A trial treatment with dexmedetomidine, a central acting alpha2-agonist, to control symptoms of PAID was initiated 12 days after injury. PAID-related events subsided during the 72-h infusion protocol of 0.2-0.7 mcg/kg/h. No further events were noted after termination of the 72-h infusion.

CONCLUSIONS

Dexmedetomidine may be a novel pharmacologic agent to aid in abrogating PAID.

The Adrenergic Pharmacology of Sympathetically-Maintained Pain

The authors seek to highlight some of the recent advances in understanding the pharmacology and pathophysiology of sympathetically-maintained pain, and to develop alternate, and possibly more specific, diagnostic tests for this phenomenon. Mechanical hyperalgesia in sympathetically-maintained pain can be explained by central sensitization so that the activation of A-beta mechanoreceptors now causes pain. The sensitization of central pain-signaling neurons is dynamic and reversible. The authors propose that an ongoing input from peripheral nociceptive afferents is necessary to maintain central sensitization. This nociceptive input may be due to an alpha-adrenoceptor mediated excitatory action of sympathetic efferents on sensory nerves that is independent of neurovascular transmission.

Lidocaine+clonidine for maxillary infiltration anaesthesia: parameters of anaesthesia and vascular effects

The local anaesthetic and haemodynamic parameters achieved by lidocaine with clonidine or epinephrine, administered for maxillary infiltration anaesthesia, were studied in 40 patients (American Society of Anesthesiologists, physical status 1) who underwent upper third molar surgery. All patients received 2 ml of 2% lidocaine with clonidine (15 microg/ml; n=20) or epinephrine (12.5 microg/ml; n=20) in a randomized, double-blind fashion. Vascular effects were evaluated on the isolated human infraorbital arteries. The parameters of maxillary infiltration anaesthsia produced by a combination of lidocaine+clonidine were similar to those obtained with lidocaine+epinephrine. In both groups, haemodynamic parameters exhibited similar variations, with the exception of a significant reduction in heart rate and systolic blood pressure in the lidocaine+clonidine group and significant increase in heart rate in the lidocaine+epinephrine group, 10 min after surgery. Clonidine (10(-7), 10(-6) and 10(-5)M) produced an endothelium-independent vasocontractile effect on the isolated human infraorbital arteries. The results of this study indicate for the first time in dental anaesthesia that the lidocaine+clonidine combination could be a useful and safe alternative to lidocaine+epinephrine for intraoral infiltration anaesthesia.

Drugs for the perioperative control of hypertension: current issues and future directions

The management of hypertension continues to pose important challenges. Recent developments have established the importance of more rigorous blood pressure control in the community. In the perioperative setting, hypertension has long been recognised as undesirable, although the adverse impact of high blood pressure on the acute risks of elective surgery may have been previously overstated.A number of agents and techniques are available to control blood pressure perioperatively. These include principally general and regional anaesthetics, alpha(2)-adrenoceptor agonists, peripheral alpha(1)- and beta-adrenoceptor antagonists, dihydropyridine calcium channel antagonists, dopamine D(1A)-receptor agonists (fenoldopam), and nitric oxide donors. Recent years have seen important developments in the receptor selectivity of new compounds and in pharmacokinetics, particularly esterase metabolism. The future study of genomics may enable us to identify patients at risk for hypertension-related adverse events and target therapies most effectively to these high-risk groups.

Brimonidine 0.2% versus brimonidine Purite 0.15% in Asian ocular hypertension

PURPOSE

The aim of this study was to evaluate the efficacy and safety of brimonidine 0.2% versus brimonidine Purite 0.15% in Asians with ocular hypertension.

METHODS

This study was a prospective, randomized, observer-masked, short-term crossover trial. Eighty-six (86) Asian subjects with newly diagnosed ocular hypertension were randomly assigned to receive either brimonidine 0.2% or brimonidine Purite 0.15%, both dosed twice a day for 4 weeks. Subjects were then washed out for 6 weeks and switched to the opposite treatment for 4 weeks.

RESULTS

The baseline intraocular pressure (IOP) was 24.4 +/- 2.45 mmHg for brimonidine 0.2% and 24.39 +/- 2.56 mmHg for brimonidine Purite 0.15% (P = 0.985). The IOP was at trough drug effect after 4 weeks of brimonidine 0.2% and brimonidine Purite 0.15% therapy were 20.10 +/- 2.01 mmHg and 21.00 +/- 1.67 mmHg (P = 0.001), respectively. The IOP at peak drug effect after 4 weeks of brimonidine 0.2% and brimonidine Purite 0.15% treatment were 18.10 +/- 1.73 mmHg and 18.20 +/- 1.71 mmHg (P = 0.518), respectively. Brimonidine 0.2% was found to cause more allergic conjunctivitis than brimonidine Purite 0.15% (P < 0.001).

CONCLUSIONS

Brimonidine 0.2% has a higher potency of lowering IOP than brimonidine Purite 0.15% at trough when used twice-daily. However, ocular allergic reaction was more frequent and severe with brimonidine 0.2% than with brimonidine Purite 0.15%.

Inhibitory effects of the alpha-2 adrenergic agonists clonidine and dexmedetomidine on enhanced airway tone in ovalbumin-sensitized guinea pigs

BACKGROUND AND OBJECTIVE

The alpha-2 adrenergic agonists clonidine and dexmedetomidine are used as an antihypertensive and a sedative, respectively. The aim of this study was to determine the effects of these agonists on ovalbumin-sensitized airway tone in guinea pigs.

METHODS

The animals were divided into two groups: control and sensitized. The sensitized group received ovalbumin intraperitoneally and was boosted by exposure to aerosolized ovalbumin. The effects of the alpha-2 agonists were investigated by measuring (1) total lung resistance and (2) smooth muscle tension using a tracheal ring preparation.

RESULTS

In the control group, acetylcholine significantly increased total lung resistance in a dose-dependent manner. In the sensitized animals, total lung resistance was significantly higher (by 95%) at 6 mug kg-1 acetylcholine than that in the control group. Both clonidine and dexmedetomidine had a slight but significant inhibitory effect on the response curve of lung resistance at higher concentrations of carbachol, a potent muscarinic receptor agonist. Similar to the data obtained in the control group, both clonidine and dexmedetomidine significantly decreased total lung resistance and the inhibitory effects of these alpha-2 agonists on lung resistance were significantly distinguishable. Similar direct inhibitory effects of the alpha-2 agonists on carbachol-induced muscle contraction were observed in both the control and sensitized groups, the inhibitory effects in the sensitized group being significantly greater.

CONCLUSION

Both clonidine and dexmedetomidine can relax the airway even in the hyper-reactive state.

[Drug therapy of opioid withdrawal]

Although the opiate dependence is of low frequency in our midst, it is important to know its management because it requires medical treatment in most cases. At present, in our country, we may classify the different patient populations able to submit an opioid withdrawal syndrome in patients undergoing chronic treatment with opioids, patients in intensive care units, neonatal mother addicted patients and addicts from the general population or linked to the health system. Detoxification programs are typically characterized by a low rate of completion of treatment and a high rate of relapse. The opioid withdrawal syndrome is objectively and subjectively severe and moderate and the goals of the therapy for the Opiates Withdrawal Syndrome are: to prevent or reduce the objective and subjective symptoms of abstinence; to prevent or treat its most serious complications; to treat preexisting or concurrent psychiatric disorders; to reduce the frequency or severity of relapses and to rehabilitate in the long term.

Treatment of menopausal symptoms

Vasomotor symptoms affect the majority of postmenopausal women. Given the risks of hormone replacement therapy, alternative treatments for hot flashes have emerged over recent years. This article will review currently available treatments for hot flashes, including hormonal and non-hormonal therapies.

Primary open angle glaucoma: an overview on medical therapy

The purpose of this review is to discuss the topics relevant to the use of intraocular pressure-lowering strategies, which remains the first line in the management of glaucoma. Estimates of blindness from glaucoma and identification of risk factors remain of interest for all ophthalmologists. New functional tests offer promise for better detection and more accurate diagnosis of glaucoma. We finally discuss the impact of various glaucoma therapies, the principles of monotherapy and fixed combinations, which offer benefits of convenience, cost, and safety.

Costs and persistence of brimonidine versus brinzolamide in everyday glaucoma care: an analysis conducted on the UK General Practitioner Research Database

OBJECTIVE

To compare the persistence and costs of brimonidine versus brinzolamide therapy according to data collected by the UK General Practitioner Research Database (GPRD).

METHODS

Patients with diagnoses of ocular hypertension or glaucoma, or treated for glaucoma by surgery or laser therapy were identified. Selected patients were prescribed either brimonidine or brinzolamide as monotherapy. Treatment failure was defined as a glaucoma prescription change (adding, removing or replacing a drug, or initiating surgery or laser therapy). Times to treatment failure were compared with an adjusted Cox model using a propensity score method.

RESULTS

A total of 2,172 patients received brimonidine and 485 brinzolamide. Mean age was 69.5 years and 46.4% were male. Age and gender did not differ significantly whereas disease duration was longer with brinzolamide. Treatment failure at 1 year was experienced by 47.7% of patients given brinzolamide and by 55.9% given brimonidine (p<0.001). The hazard ratio for failure was less with brinzolamide (0.79: p<0.001) compared to brimonidine, after adjusting for age, gender, comorbidities and duration of follow-up. Adjusted annual costs of glaucoma management (in pound2005) were significantly (p<0.0042) lower with brinzolamide (pound196) than brimonidine (pound230).

CONCLUSIONS

According to data from everyday practice collected by the UK GPRD, brinzolamide was found to be more persistent than brimonidine when given as glaucoma monotherapy. Patients continued longer with brinzolamide treatment at a lower cost.

Successful but prolonged resuscitation after local anesthetic-induced cardiac arrest: is clonidine effective?

Local anesthetics when injected intravascularly result in serious cardiac complications including therapy-resistant cardiac arrest. We report a case of cardiac arrest after lumbar plexus block using a combination of 0.5% bupivacaine and 2% lidocaine with epinephrine (1:200.000). Resuscitation was performed by a combination of chest compression, repeated external countershocks and i.v.epinephrine. Clonidine had poor effect. The whole resuscitation required 90 minutes. The patient was discharged four days later without any sequelae. Blood sampling at 10 minutes showed a concentration of 2.02 mg/l lidocaine and 0.87 mg/l bupivacaine. Prolonged resuscitation is necessary in local anesthetic-induced cardiac arrest.

Effects of the CRF receptor antagonist D-Phe CRF(12-41) and the alpha2-adrenergic receptor agonist clonidine on stress-induced reinstatement of nicotine-seeking behavior in rats

Tobacco dependence is a chronic disorder that is characterized by relapse after periods of abstinence. It has been hypothesized that the activation of brain stress systems mediates stress-induced relapse to smoking. The aim of these experiments was to investigate the role of corticotropin-releasing factor (CRF) and norepinephrine in stress-induced reinstatement of extinguished nicotine-seeking behavior. Rats were allowed to self-administer nicotine under a fixed-ratio 5 schedule for 14 days and then nicotine-seeking behavior was extinguished by substituting saline for nicotine. In experiment 1, footshocks reinstated extinguished nicotine-seeking behavior. In experiment 2, there was a trend for the CRF(1/2) receptor antagonist D-Phe CRF((12-41)) (5, 25microg, icv) to decrease stress-induced reinstatement of nicotine-seeking behavior. Footshock-induced reinstatement of nicotine-seeking behavior was observed only in a subset of stress-responsive rats (71%). D-Phe CRF((12-41)) significantly attenuated stress-induced reinstatement of nicotine-seeking behavior in this subset of rats. In experiment 3, the alpha2-adrenergic receptor agonist clonidine (20, 40microg/kg, sc) attenuated footshock-induced reinstatement of nicotine-seeking behavior. In experiment 4, the effects of D-Phe CRF((12-41)) and clonidine on responding for chocolate-flavored food pellets was investigated in order to determine if these compounds have sedative effects. D-Phe CRF((12-41)) did not affect responding for food pellets. Clonidine slightly, but significantly, decreased responding for food pellets. Clonidine decreased responding for food to a lesser degree than it decreased stress-induced reinstatement of nicotine-seeking behavior. These data provide support for the hypothesis that an increased activity of brain CRF and norepinephrine systems mediates stress-induced relapse to nicotine-seeking behavior.

The efficacy and adverse effects of topical phenylephrine for anal incontinence after low anterior resection in patients with rectal cancer

BACKGROUND

Anal incontinence is experienced by some patients with rectal cancer who received low anterior resection. This study was to examine the efficacy and adverse effects of the alpha-1 adrenergic agonist phenylephrine, which causes contraction of the internal anal sphincter and raises the resting pressure in these patients.

PATIENTS AND METHODS

Thirty-five patients with anal incontinence were treated with 30% phenylephrine or a placebo randomly allocated in a double-blind study. The efficacy of the drug was assessed by changes in the following standardized questionnaire scores: the fecal incontinence severity index (FISI), fecal incontinence quality of life (FIQL) scales, and a global efficacy question. Anal sphincter function was evaluated using anorectal manometry.

RESULTS

Phenylephrine did not improve either the FISI score or any of the four FIQL scores. Five of 17 (29%) patients reported subjective improvement after phenylephrine compared with 4 of 12 (33%) using the placebo. The maximum resting anal pressure did not differ between baseline and after 4 weeks application of phenylephrine (30.0 to 27.3 mmHg). In the phenylephrine group, allergic dermatitis was developed in five patients and headache in two.

CONCLUSION

In the patients with anal incontinence after low anterior resection for rectal cancer, phenylephrine gel did not seem to be helpful in relieving symptoms with some adverse effects.

Autonomic dysfunction in tetanus - what lessons can be learnt with specific reference to alpha-2 agonists?

Severe tetanus is seen infrequently in the developed world, but often requires intensive care support. Mechanical ventilation with neuromuscular blockade and heavy sedation, good wound care and prompt administration of antitoxin are important. The management of autonomic dysfunction remains challenging. We measured serum catecholamine levels in a patient with severe tetanus in whom autonomic crises were a major and persistent feature, and investigated the impact of sedatives plus alpha(2)-agonists on these levels. Serum adrenaline levels were elevated up to 100-fold with clinically observed crises, although noradrenaline levels were much more difficult to interpret. There was no appreciable difference in catecholamine levels following administration of alpha(2)-agonists in the doses we used, although clonidine did allow easier control of crises with other agents. This case highlights some important lessons in the management of severe tetanus.

Centrally acting antihypertensive agents: an update

Centrally acting agents stimulate alpha(2) receptors and/or imadozoline receptors on adrenergic neurons situated within the rostral ventrolateral medulla and, in so doing, sympathetic outflow is reduced. Centrally acting agents also stimulate peripheral alpha(2) receptors, which, for the most part, is of marginal clinical significance. Central a agonists have had a lengthy history of use, starting with alpha-methyldopa, which has had a dramatic decline in use, in part, because of bothersome side effects. Patients who require multidrug therapy with otherwise resistant hypertension, such as diabetic and/or renal failure patients, are typically responsive to these drugs, as are patients with sympathetically driven forms of hypertension. Perioperative forms of hypertension respond well to clonidine, a circumstance where the additional anesthesia- and analgesia-sparing effects of this drug may offer additional clinical benefits. Clonidine can be used adjunctively with other more traditional therapies in heart failure, particularly when hypertension is present. Sustained-release moxonidine, however, is associated with early mortality and morbidity when used in patients with heart failure. Escalating doses of drugs in this class often give rise to salt and water retention, in which case diuretic therapy becomes a valuable adjunctive therapy.

Orthostatic hypotension in the elderly: diagnosis and treatment

Orthostatic hypotension is a common problem among elderly patients, associated with significant morbidity and mortality. While acute orthostatic hypotension is usually secondary to medication, fluid or blood loss, or adrenal insufficiency, chronic orthostatic hypotension is frequently due to altered blood pressure regulatory mechanisms and autonomic dysfunction. The diagnostic evaluation requires a comprehensive history including symptoms of autonomic nervous system dysfunction, careful blood pressure measurement at various times of the day and after meals or medications, and laboratory studies. Laboratory investigation and imaging studies should be based upon the initial findings with emphasis on excluding diagnoses of neurodegenerative diseases, amyloidosis, diabetes, anemia, and vitamin deficiency as the cause. Whereas asymptomatic patients usually need no treatment, those with symptoms often benefit from a stepped approach with initial nonpharmacological interventions, including avoidance of potentially hypotensive medications and use of physical counter maneuvers. If these measures prove inadequate and the patient remains persistently symptomatic, various pharmacotherapeutic agents can be added, including fludrocortisone, midodrine, and nonsteroidal anti-inflammatory drugs. The goals of treatment are to improve symptoms and to make the patient as ambulatory as possible rather then trying to achieve arbitrary blood pressure goals. With proper evaluation and management, the occurrence of adverse events, including falls, fracture, functional decline, and myocardial ischemia, can be significantly reduced.

Effectiveness of low-dose naltrexone in the post-detoxification treatment of opioid dependence

BACKGROUND

The clinical use of naltrexone (NTX) in the treatment of opioid dependence has been limited because of poor compliance and inconsistent outcomes. In particular, the therapeutic benefit of extended treatment with NTX after opioid detoxification is unclear. The present study evaluated whether the augmentation with low-dose NTX during the post-detoxification treatment of opioid dependence would improve outcomes.

METHODS

In an open-label naturalistic design, 435 opioid-dependent patients who had completed inpatient detoxification were offered the choice of entering 1 of the 2 outpatient treatment arms: clonidine extended treatment (CET) (clonidine + psychosocial treatment), or enhanced extended treatment (EET) (oral NTX [1-10 mg/d] + CET) for 21 days. The primary outcome measure was retention in treatment. Secondary outcomes included abstinence from opioids, dropouts, and adherence to postdischarge care.

RESULTS

One hundred sixty-two patients (37.2%) accepted EET. Subjects receiving EET stayed longer in the program (F = 64.4; P = 0.000), were less likely to drop out, used less opioids, and followed through with referral to long-term outpatient treatment in a higher number, compared with patients in the CET arm (P = 0.000 in each case). The NTX + clonidine combination was safe and well tolerated.

CONCLUSIONS

This preliminary study indicates the potential benefit of augmentation with low-dose NTX to improve outcomes after opioid detoxification for a preferred group of patients. Randomized controlled trials are necessary to further evaluate the role of low-dose NTX in the outpatient treatment of opioid dependence.

Impact of norepinephrine and fluid on cerebral oxygenation in experimental hemorrhagic shock

Few data exist regarding resuscitation of hypovolemic shock in infants, and alternative strategies such as vasopressor therapy merit further evaluation. However, the effects of norepinephrine on cerebral perfusion and oxygenation during hemorrhagic shock in the pediatric population are still unclear. Eight anesthetized piglets were subjected to hypotension by blood withdrawal of 25 mL/kg. Norepinephrine was titrated to achieve baseline mean arterial blood pressure (MAP), and cerebral oxygenation was determined by brain tissue Po2 (Ptio2) and near-infrared spectroscopy-derived tissue oxygen index (TOI). Then, norepinephrine was stopped, MAP was allowed to decrease again below 30 mm Hg, and shed blood was retransfused. During hemorrhage, TOI dropped from 69+/-3 to 59+/-3%, and Ptio2 from 29+/-6 to 13+/-1 mm Hg (mean+/-SEM; p<0.001). Following norepinephrine, cerebral perfusion pressure (CPP) could be restored immediately, whereas TOI and Ptio2 did not increase significantly. In contrast, following retransfusion, TOI and Ptio2 increased to 68+/-3% and 27+/-7 mm Hg reaching baseline values, respectively. In conclusion, while norepinephrine increased CPP immediately, cerebral oxygenation as reflected by TOI and Ptio2 could not be improved by norepinephrine, but only by retransfusion.

A case of neurally mediated syncope induced by laughter successfully treated with combination of propranolol and midodrine

A 69-year-old man had been suffering from recurrent syncope induced by laughter since the age of 58. His syncope was reproduced by head-up tilt testing with isoproterenol infusion and we concluded that his laughter-induced syncope was one type of neurally mediated syndrome (NMS). His daughter also had NMS and her syncope was treated with propranolol. Propranolol and midodrine hydrochloride, an alpha(1)-adrenergic stimulant, were effective at preventing his laughter-induced syncope. This is a case report of laughter-induced syncope with a familial predisposition successfully treated with the combination of the nonselective beta-blocker propranolol and the alpha(1)-stimulator midodrine.

Trends in medication prescribing for pediatric sleep difficulties in US outpatient settings

OBJECTIVES

This study examined trends in physician-prescribing of medications for children with sleep difficulties in outpatient settings in the US. Additionally, we explored the incidence of physician prescribing patterns of medications with high abuse potential for children with sleep difficulties.

METHODS

A cross-sectional study was conducted on patients aged < or =17 years with sleep difficulties from 1993-2004 using data from the National Ambulatory Medical Care Survey (NAMCS). Office visits were considered related to sleep difficulties if relevant ICD-9 codes were recorded and if sleep difficulties were reported as the reason for the visits. Medications were retrieved using the NAMCS drug codes, and all analyses were weighted to determine national estimates.

RESULTS

During 1993 to 2004, approximately 18.6 million visits occurred for sleep related difficulty in children. The highest percentage of visits were by school-aged children (6 to 12 years). Pediatricians saw 35% of patients, psychiatrists saw 24%, and general/family practice physicians saw 13% of the patients. Eighty-one percent of visits among children with sleep difficulties resulted in a prescription for a medication. Many of these medications prescribed lack FDA approved labeling to assure their effectiveness and safety in this population.

CONCLUSION

The findings of this study suggest that physicians frequently prescribed medications for sleep difficulties in children in US outpatient settings. Of particular concern is prescribing of many unapproved medications for this population.

Midodrine improves ejaculation in spinal cord injured men

PURPOSE

We evaluated the effect of the alpha1-adrenergic agonist midodrine given orally for anejaculation in spinal cord injured men.

MATERIALS AND METHODS

A total of 185 spinal cord injured patients who reported absent ejaculation during sexual intercourse and who failed to respond to penile vibratory stimulation were treated with midodrine 30 to 120 minutes before a new stimulation. The procedure was repeated weekly, increasing doses by 7.5 mg to a maximum of 30 mg. Cardiovascular effects were monitored throughout the procedure.

RESULTS

Antegrade or retrograde ejaculation was achieved in 102 spinal cord injured men (64.6%). A positive response was more frequent in patients with complete lesions (American Spinal Injury Association A) and upper motor neuron lesions above T10. Midodrine induced a significant but moderate increase (maximum 10 mm Hg) in mean arterial pressure in all patients. The highest systolic blood pressure (more than 200 mm Hg) was seen in patients with quadriplegia. No other significant side effect was recorded. The average dose of midodrine required for ejaculation was 18.7 mg.

CONCLUSIONS

Midodrine is a safe and efficient adjunct to penile vibratory stimulation for anejaculation in spinal cord injured patients.

ST91 [2-(2,6-diethylphenylamino)-2-imidazoline hydrochloride]-mediated spinal antinociception and synergy with opioids persists in the absence of functional alpha-2A- or alpha-2C-adrenergic receptors

Agonists acting at alpha2-adrenergic receptors (alpha2ARs) produce antinociception and synergize with opioids. The alpha2ARs are divided into three subtypes, alpha(2A)AR, alpha(2B)AR, and alpha(2C)AR. Most alpha2AR agonists require alpha(2A)AR activation to produce antinociception and opioid synergy. The same subtype also mediates the side effect of sedation, which limits the clinical utility of these compounds. Identification of a non-alpha(2A)AR-mediated antinociceptive agent would enhance the therapeutic utility of alpha2AR agonists in pain management. Previous studies have suggested that the alpha2AR agonist ST91 [2-(2,6-diethylphenylamino)-2-imidazoline hydrochloride] has a nonsedating, non-alpha(2A)AR mechanism of action. We examined the pharmacology of spinal ST91 and its interaction with the delta-opioid agonist deltorphin II (Tyr-D-Ala-Phe-Glu-Val-Val-Gly amide) in mice lacking either functional alpha(2A)ARs or alpha(2C)ARs. All drugs were administered by direct lumbar puncture, and drug interactions were evaluated using isobolographic analysis. In contrast to the majority of alpha2AR agonists, ST91 potency was only moderately reduced (3-fold) in the absence of the alpha(2A)AR. Studies with the alpha2AR subtype-preferring antagonists BRL-44408 (2-[2H-(1-methyl-1,3-dihydroisoindole)methyl]-4,5-dihydroimidazole maleate) and prazosin [[4-(4-amino-6,7-dimethoxy-quinazolin-2-yl) piperazin-1-yl]-(2-furyl)methanone] and the pan-alpha2AR antagonist SKF-86466 (6-chloro-2,3,4,5-tetrahydro-3-methyl-1-H-3-benzazepine) suggest a shift from alpha(2A)AR to the other alpha2AR subtype(s) in the absence of alpha(2A)AR. Antinociceptive synergy with deltorphin II was preserved in the absence of either alpha(2A)AR or alpha(2C)AR. In conclusion, ST91 activates both alpha(2A)AR and non-alpha(2A)AR subtypes to produce spinal antinociception and opioid synergy. This study confirms that the spinal pharmacology of ST91 differs from that of other alpha2AR agonists and extends those data to include spinal synergy with opioid agonists. The unique profile of ST91 may be advantageous in pain management.

The cardioprotective effect of dexmedetomidine on global ischaemia in isolated rat hearts

AIM

Dexmedetomidine is a highly specific and selective alpha-2 adrenergic agonist that is now widely used in the intensive care setting. Many intensive care unit (ICU) patients are at risk of respiratory or cardiac arrest. This study was conducted to determine whether dexmedetomidine exhibits a cardioprotective effect on global ischaemia and subsequent myocardial infarction.

METHODS

Isolated rat hearts were subjected to 30 min of global ischaemia followed by 120 min reperfusion, with administration of 0, 1 and 10nM dexmedetomidine during the pre-ischaemic period (n=7 each group). Secondly, 1 microM yohimbine, an alpha-2 antagonist, was given during the pre-ischaemic period, alone or in combination with 10 nM dexmedetomidine (n=7 each group).

RESULTS

Dexmedetomidine administration reduced coronary flow significantly (103.6+/-4.7%, 77.9+/-3.7, 63.7+/-6.1%, of the baseline values for 0, 1 and 10 nM dexmedetomidine, respectively), and yohimbine administration reversed this effect (88.0+/-2.2%). Dexmedetomidine improved the infarct size at each concentration (45.3+/-3.6, 30.2+/-3.3, and 21.2+/-2.3% of the total left ventricular mass for 0, 1, and 10nM dexmedetomidine, respectively), which was also reversed by yohimbine (43.6+/-1.4%).

CONCLUSION

Dexmedetomidine exhibited a cardioprotective effect on global ischaemia in the isolated rat heart model, which was mediated by alpha-2 adrenergic stimulation.

Persistency rates for prostaglandin and other hypotensive eyedrops: population-based study using pharmacy claims data

BACKGROUND

Effective management of ocular hypertension requires patients to be persistent with their treatment regimen. We evaluated patients' persistency with hypotensive eyedrops commonly used to treat glaucoma and ocular hypertension.

METHODS

This large, population-based, retrospective, cohort study used pharmacy claims data for concessional patients from the Australian Pharmaceutical Benefits Scheme (July 1999-June 2005). Resupply rates for prostaglandins, beta-blockers, alpha-agonists and carbonic anhydrase inhibitors were analysed using life tables and Cox regression. Two populations, based on patients' supply histories, were examined: (i) 'new to this eyedrop'- patients who had used other hypotensive eyedrops before (presumably, previously diagnosed with glaucoma or ocular hypertension); and (ii) 'new to any eyedrop'- patients who were using their first hypotensive eyedrop (presumably, newly diagnosed with glaucoma or ocular hypertension).

RESULTS

Data were obtained for 14,359,618 supplies of commonly used hypotensive eyedrops to 357,099 concessional patients. For both populations, resupply rates were highest for prostaglandins or the dorzolamide-timolol combination eyedrops, compared with beta-blockers, alpha-agonists or carbonic anhydrase inhibitors. Among the prostaglandins, there was no significant difference in the risk of ceasing supply between latanoprost and bimatoprost, but the risk was significantly higher for travoprost.

CONCLUSIONS

Based on resupply rates from a national pharmacy claims database, patients supplied with ocular hypotensive eyedrops were most persistent with prostaglandin (bimatoprost, latanoprost and travoprost) and dorzolamide-timolol combination eyedrops. Among the prostaglandins, persistency was highest with, and similar between, bimatoprost and latanoprost. Persistency should be taken into account when selecting the most appropriate eyedrop to treat glaucoma and ocular hypertension.

Effect of prophylactic brimonidine instillation on bleeding during strabismus surgery in adults

PURPOSE

To investigate the effects of preoperative brimonidine-purite 0.15% instillation on intraoperative bleeding and postoperative subconjunctival hemorrhage during strabismus surgery in adult patients.

DESIGN

Randomized comparative interventional case series.

METHODS

One hundred and eighteen eyes of 90 consecutive adult patients were instilled with either a single drop of brimonidine-purite 0.15% (42 eyes), phenylephrine 1% (38 eyes), or sodium hyaluronate 0.1% (38 eyes) 15 minutes prior to strabismus surgery. Intraoperative bleeding and postoperative subconjunctival hemorrhage were graded on a scale of one to three. The scores were compared among the study groups.

RESULTS

Scores of the intraoperative bleeding and the postoperative subconjunctival hemorrhage of the treatment groups were significantly less than that of the control group (P < .001). The scores of the brimonidine group were similar to those of the phenylephrine group (intraoperative bleeding score, P = .405; subconjunctival hemorrhage score, P = .722).

CONCLUSIONS

Topical brimonidine administration before strabismus surgery may reduce intraoperative bleeding and postoperative subconjunctival hemorrhage in adult patients.

Levosimendan improves the initial outcome of cardiopulmonary resuscitation in a swine model of cardiac arrest

BACKGROUND

Cardiac arrest remains the leading cause of death in Western societies. Advanced Life Support guidelines propose epinephrine (adrenaline) for its treatment. The aim of this study was to assess whether a calcium sensitizer agent, such as levosimendan, administered in combination with epinephrine during cardiopulmonary resuscitation, would improve the initial resuscitation success.

METHODS

Ventricular fibrillation was induced in 20 Landrace/Large-White piglets, and left untreated for 8 min. Resuscitation was then attempted with precordial compressions, mechanical ventilation and electrical defibrillation. The animals were randomized into two groups (10 animals each): animals in Group A received saline as placebo (10 ml dilution, bolus) + epinephrine (0.02 mg/kg), and animals in Group B received levosimendan (0.012 mg/kg/10 ml dilution, bolus) + epinephrine (0.02 mg/kg) during cardiopulmonary resuscitation. Electrical defibrillation was attempted after 10 min of ventricular fibrillation.

RESULTS

Four animals in Group A showed restoration of spontaneous circulation and 10 in Group B (P = 0.011). The coronary perfusion pressure, saturation of peripheral oxygenation and brain regional oxygen saturation were significantly higher during cardiopulmonary resuscitation in Group B.

CONCLUSIONS

A calcium sensitizer agent, when administered during cardiopulmonary resuscitation, significantly improves initial resuscitation success and increases coronary perfusion pressure during cardiopulmonary resuscitation.

[Efficacy, tolerance and acceptability of Incontex in spayed bitches with urinary incontinence]

A clinical study about efficacy and acceptance of Incontex in spayed bitches with urinary incontinence was performed. In a randomised, double-blinded study the efficacy and acceptance of Incontex (Dr. E. Gräub AG, Bern, Schweiz) in bitches with urethral sphincter incompetence due to spaying was evaluated under field conditions. The active ingredient of the Incontex Syrup is phenylpropanolamine (PPA), an alpha1-adrenergic agonist. The study was performed using 24 spayed, incontinent bitches. Over a first period of treatment of 30 days the bitches received either Incontex, at 1.5 mg/kg twice per day, or a placebo. In the second period of 30 days all 24 bitches were treated with Incontex at the recommended dose. Any changes in the incontinence compared with the situation before the study were evaluated.

RESULTS

Of 24 bitches 21 (88%) became continent and in 2 bitches (8%) urinary incontinence improved. In only 1 bitch (4%) the medication did have no effect. Five bitches (21%) showed side effects. The acceptance of Incontex was good.

CONCLUSION AND CLINICAL RELEVANCE

Incontex can be recommended as an efficient and well-tolerated medication for the treatment of bitches with urinary incontinence after spaying. The oral application of 1.5mg/kg BW phenylpropanolamine twice daily has been approved.

Special considerations in low-tension glaucoma

Low-pressure (low-tension) glaucoma is reviewed in relation to neuroprotection, that is, the therapeutic strategy to keep neurons living and functionally connected to targets within the brain. Baseline results of the Low-Pressure Glaucoma Treatment Study (LoGTS) are reviewed.

Pre-medication with intravenous clonidine suppresses fentanyl-induced cough

BACKGROUND

A reflex cough is often observed after an intravenous bolus of fentanyl. This study was conducted to determine whether pre-treatment with intravenous clonidine could effectively attenuate fentanyl-induced cough.

METHODS

Three hundred ASA I-II patients, aged between 18 and 80 years, undergoing various elective surgeries, were enrolled in this study. All patients were randomly assigned to one of two groups treated with intravenous clonidine 2 microg/kg (clonidine group) or the same volume of normal saline (control group). Intravenous fentanyl (2 microg/kg in 2 s) was injected 2 min after the clonidine or normal saline injection. Changes in the hemodynamics, auditory evoked potentials (AEPs) and Observer Assessment of Alertness/Sedation (OAA/S) rating scale were recorded before and 2 min after the clonidine or normal saline injection and 1 min after the fentanyl injection. The number of coughs 1 min after the fentanyl injection was also recorded.

RESULTS

Patients in the clonidine group showed a significantly lower incidence of cough than those in the control group (17.3% vs. 38.7%, respectively; P < 0.01). The blood pressure was lower in the clonidine group than in the control group. There were no significant differences in AEP or OAA/S rating scale.

CONCLUSIONS

Pre-treatment with intravenous clonidine (2 microg/kg) suppressed the reflex cough induced by fentanyl, with mild hemodynamic changes. Therefore, intravenous clonidine may be a clinically useful method of suppressing fentanyl-induced cough.

alpha2-Adrenergic receptor agonists for the treatment of attention-deficit/hyperactivity disorder: emerging concepts from new data

Recent developments in the field of neuroscience have illuminated the understanding of the neural circuits impaired in attention-deficit/hyperactivity disorder (ADHD) and the mechanism of action of treatments used to treat this condition. There is an exciting confluence between emerging studies in basic neurobiology and the genetic, neuroimaging, and neuropsychological analyses of ADHD. The following provides a brief review of this field, explaining how compounds like guanfacine and the traditional stimulant medications can reduce the core symptoms of ADHD by optimizing the neurochemical environment in the prefrontal cortex (PFC). Knowledge of these basic mechanisms may inform our medication choices and facilitate treatment of ADHD and related disorders.

Alteration of retinal intrinsic survival signal and effect of α2–adrenergic receptor agonist in the retina of the chronic ocular hypertension rat

The purpose of this study is to examine the retinal expression of intrinsic cell survival molecules and to elucidate the effect of an α2-adrenergic receptor agonist in the chronic ocular hypertensive rat model. Chronic ocular hypertension was induced in both eyes of each rat by episcleral vein cauterization. Two five-microliter drops of the selective α2-adrenoceptor agonist brimonidine 0.2% (Alphagan; Allergan Inc., Irvine, CA, USA) were topically administered twice daily for up to eight weeks in one eye. The fellow eye received balanced salt solution as a control. Protein and mRNA expression were evaluated at 1, 4, and 8 weeks after injury. Retinal expression of BDNF, Akt, and GFAP was assessed using immunohistochemistry. Retinal levels of mRNA for BDNF, bcl-2, and bcl-xL were determined using semi-quantitative RT-PCR. Retinal ganglion cell (RGC) density was evaluated after retrograde labeling with 4-Di-10-ASP (DiA). A significant decrease in RGC density was observed in ocular hypertensive eyes. Cauterized eyes showed an increase in GFAP expression from one week after injury, and the expression of bcl-2, bcl-xL, and BDNF mRNA was also increased. Treatment of ocular hypertensive eyes with brimonidine resulted in a reduction in RGC loss, a decrease in the level of GFAP immunoreactivity, and an increment in BDNF mRNA and p-Akt expression. Brimonidine appears to protect RGCs from neurodegeneration through mechanisms involving α2-adrenergic receptor mediated survival signal activation and up-regulation of endogenous neurotrophic factor expression in the chronic ocular hypertensive rat retina.

Midodrine: insidious development of urologic adverse effects in patients with spinal cord injury: a report of 2 cases

Midodrine, a prodrug, is converted after oral administration into its active drug, desglymidodrine, which acts as an alpha(1)-adrenoceptor stimulant. Midodrine is prescribed for the treatment of neurogenic orthostatic hypotension in patients with spinal cord injury. By virtue of its alpha(1)-adrenergic effects, midodrine causes an increase in the tone of the vesical sphincter, which may silently lead to progressive retention of urine, particularly in patients with spinal cord injury who void urine spontaneously. Further, midodrine may aggravate detrusor-sphincter dyssynergia, which can lead to hydroureteronephrosis. A 68-year-old man with C-4 tetraplegia was voiding urine satisfactorily through reflex detrusor contractions. He was prescribed midodrine (5 mg at 8:00 AM, 5 mg at 1:00 PM, and 2.5 mg at 10:00 PM) for postural hypotension. During the next 7 wk, this patient experienced severe leg spasms while passing urine, and the flow of urine became very slow. Intravenous urography showed bilateral hydroureteronephrosis, although an earlier study had revealed normal kidneys. Midodrine therapy was stopped, and intermittent catheterization 4 times a day, along with oral oxybutynin, was started. After midodrine was discontinued, the leg spasms during passage of urine and slowing of the urine stream coincident with the spasms disappeared completely. The patient was able to pursue activities of daily living without taking midodrine. A 40-year-old man with C-7 tetraplegia was passing urine spontaneously with no problem. For postural hypotension, he was prescribed midodrine (5 mg in the morning and 2.5 mg at lunchtime), fludrocortisone (100 microg daily), and ephedrine (15 mg by mouth, taken 10 min before getting up in the morning). Three months later, the patient presented with sweating. During the day, he would pass only small amounts of urine, but from evening onward, he would void large volumes of urine, and the sweating would diminish. Intravenous urography showed vesical diverticula; a postmicturition film revealed moderate residual urine. This patient was able to stop taking the second dose of midodrine, but he required midodrine and ephedrine in the morning to enable him to get up without feeling dizzy. After the noon midodrine dose was stopped, the patient's sweating diminished by late afternoon. During the morning hours, however, he continued to sweat and had difficulty passing urine. Intermittent catheterization was not possible in the community setting, and the patient remains under close follow-up. These cases illustrate that patients with cervical spinal cord injury who void spontaneously may develop insidious urologic adverse effects after taking midodrine for postural hypotension. When patients with spinal cord injury develop urologic adverse effects while taking midodrine, the drug should be stopped, and other pharmacologic agents (eg, fludrocortisone) and nonpharmacologic methods should be prescribed for management of orthostatic hypotension. If a patient continues to require midodrine to control postural hypotension, intermittent catheterization combined with antimuscarinic therapy (eg, oxybutynin) should be recommended instead of spontaneous voiding.

Prolonged supine hypertension due to midodrine use in an orthostatic hypotensive child

Midodrine hydrochloride is a potent peripherally-acting alpha1 agonist that is well absorbed and rapidly metabolized to its active metabolite. It has been used for the treatment of refractory syncope but has the important side effect of supine hypertension. A 10-year-old boy with severe symptomatic orthostatic hypotension was treated with midodrine. After therapy, syncope attacks ceased but he suffered nighttime headaches, nausea, transient rash and itchy/prickly scalp. Midodrine was discontinued when supine hypertension was noticed. However, his supine hypertension continued until day 19 after discontinuation. This case shows that patients receiving midodrine should be observed for supine hypertension for a prolonged period.