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Biomedical subjects

A Markham

Publications and source records attributed to A Markham.

At least 19 recordsLinked to original sources

Long-acting isosorbide mononitrate.

Elantan long (EL) is the only long-acting isosorbide mononitrate formulation based on a controlled membrane principle. 30% of the dose is available for immediate release and the remaining 70% is gradually released over time. After oral administration, isosorbide mononitrate EL has a quick onset of action (30 minutes) and effects are evident for up to 17 hours. The antianginal effects of once-daily isosorbide mononitrate EL 50 to 100mg were generally similar to those of conventional isosorbide mononitrate or isosorbide dinitrate 10 to 20mg twice or 3 times daily, or sustained-release nifedipine 20mg twice or 3 times daily. Patients tended to show a better response with once-daily isosorbide mononitrate EL 50mg than with bupranolol 100mg. Patients showed significantly greater improvement in some quality-of-life indices with once-daily isosorbide mononitrate EL than with twice or 3 times daily regimens of conventional isosorbide mononitrate or isosorbide dinitrate. Tolerance did not develop after 13 months of once-daily administration of isosorbide mononitrate EL. No rebound increase in incidence of ischaemic episodes was observed after discontinuation of the drug.

Angina Pectoris

Finasteride: a review of its use in male pattern hair loss.

UNLABELLED: The 5alpha-reductase inhibitor finasteride blocks the conversion of testosterone to dihydrotestosterone (DHT), the androgen responsible for male pattern hair loss (androgenetic alopecia) in genetically predisposed men. Results of phase III clinical studies in 1879 men have shown that oral finasteride 1 mg/day promotes hair growth and prevents further hair loss in a significant proportion of men with male pattern hair loss. Evidence suggests that the improvement in hair count reported after 1 year is maintained during 2 years' treatment. In men with vertex hair loss, global photographs showed improvement in hair growth in 48% of finasteride recipients at 1 year and in 66% at 2 years compared with 7% of placebo recipients at each time point. Furthermore, hair counts in these men showed that 83% of finasteride versus 28% of placebo recipients had no further hair loss compared with baseline after 2 years. The clinical efficacy of oral finasteride has not yet been compared with that of topical minoxidil, the only other drug used clinically in patients with male pattern hair loss. Therapeutic dosages of finasteride are generally well tolerated. In phase III studies, 7.7% of patients receiving finasteride 1 mg/day compared with 7.0% of those receiving placebo reported treatment-related adverse events. The overall incidence of sexual function disorders, comprising decreased libido, ejaculation disorder and erectile dysfunction, was significantly greater in finasteride than placebo recipients (3.8 vs 2.1%). All sexual adverse events were reversed on discontinuation of therapy and many resolved in patients who continued therapy. No other drug-related events were reported with an incidence > or =1% in patients receiving finasteride. Most events were of mild to moderate severity. Oral finasteride is contraindicated in pregnant women because of the risk of hypospadias in male fetuses. CONCLUSIONS: Oral finasteride promotes scalp hair growth and prevents further hair loss in a significant proportion of men with male pattern hair loss. With its generally good tolerability profile, finasteride is a new approach to the management of this condition, for which treatment options are few. Its role relative to topical minoxidil has yet to be determined.

Alopecia

Cytogenetics and the surgeon: an invaluable tool in diagnosis, prognosis and counselling of patients with solid tumours.

BACKGROUND: Cytogenetic studies have become an important part of tumour characterization. In a minority of tumours cytogenetic and/or molecular studies may be of help for diagnosis, selection of treatment protocols and predicting outcome. METHODS: This article reviews the literature on solid tumour translocations and established family cancer syndromes. In addition, the potential importance of genetics in management of patients with breast, ovarian and pancreatic carcinoma is reviewed. RESULTS AND CONCLUSION: Cytogenetic analysis of tumours may help confirm the diagnosis when conventional histology demonstrates no evidence of differentiation along a particular tissue pathway. For patients with well defined cancer syndromes, cytogenetic and molecular analysis offers the prospect of screening to reduce the risk of malignant disease. For many malignancies the underlying genetic anomalies are gradually being elucidated. Further studies designed to demonstrate the significance of these findings can only be undertaken if tumour material is collected and stored in optimal conditions for cytogenetic and/or molecular biological studies.

Age of Onset

Pamidronate. A review of its use in the management of osteolytic bone metastases, tumour-induced hypercalcaemia and Paget's disease of bone.

Pamidronate (APD) is a potent inhibitor of bone resorption that is useful in the management of patients with osteolytic bone metastases from breast cancer or multiple myeloma, tumour-induced hypercalcaemia or Paget's disease of bone. After intravenous administration, the drug is extensively taken up in bone, where it binds with hydroxyapatite crystals in the bone matrix. Matrix-bound pamidronate inhibits osteoclast activity by a variety of mechanisms, the most important of which appears to be prevention of the attachment of osteoclast precursor cells to bone. In patients with osteolytic bone metastases associated with either breast cancer or multiple myeloma, administration of pamidronate together with systemic antitumour therapy reduces and delays skeletal events, including pathological fracture, hypercalcaemia and the requirement for radiation treatment or surgery to bone. Pamidronate generally improves pain control. Quality-of-life and performance status scores in pamidronate recipients were generally as good as, or better than, those in patients who did not receive the drug. Overall survival does not appear to be affected by pamidronate therapy. Tumour-induced hypercalcaemia also responds well to pamidronate therapy: 70 to 100% of patients achieve normocalcaemia, generally 3 to 5 days after treatment. Response durations vary, but are commonly 3 weeks or longer, In comparative studies, pamidronate produced higher rates of normocalcaemia and longer normocalcaemic durations than other available osteoclast inhibitors, including intravenous etidronate, clodronate and plicamycin (mithramycin). In most patients with Paget's disease of bone, intravenous pamidronate reduces bone pain and produces biochemical response. Serum alkaline phosphatase levels generally fall 50 to 70% from baseline 3 to 4 months after pamidronate treatment. Biochemical response may be prolonged. Pamidronate is well tolerated by most patients. Transient febrile reactions, sometimes accompanied by myalgias and lymphopenia, occur commonly after the first infusion of pamidronate. Other reported adverse events include transient neutropenia, mild thrombophlebitis, asymptomatic hypocalcaemia and, rarely, ocular complications (uveitis and scleritis). Pamidronate should be considered for routine use together with systemic hormonal or cytotoxic therapy in patients with breast cancer or multiple myeloma and osteolytic metastases. At present, pamidronate is the drug of choice for first-line use in the management of patients with tumour-induced hypercalcaemia. It is an effective treatment for Paget's disease and is the treatment of choice where oral bisphosphonates are not an option.

Antineoplastic Agents

Pramipexole. A review of its use in the management of early and advanced Parkinson's disease.

UNLABELLED: Pramipexole is an orally active non-ergoline dopamine agonist with selective activity at dopamine receptors belonging to the D2 receptor subfamily (D2, D3, D4 receptor subtypes) and with preferential affinity for the D3 receptor subtype. It is approved as monotherapy in early Parkinson's disease and as adjunctive therapy to levodopa in patients with advanced disease experiencing motor effects because of diminished response to levodopa. The potential neuroprotective effects of pramipexole have been shown in animal and in vitro studies. Data from relatively long term (10- or 31-week) studies suggest that pramipexole monotherapy (0.375 to 6.0 mg/day) can improve activities of daily living and motor symptoms in patients with early Parkinson's disease. Pramipexole (0.375 to 4.5 mg/day for 31 or 36 weeks), as an adjunct to levodopa in advanced disease, improved activities of daily living and motor symptoms, reduced the duration and severity of 'off' periods and allowed a reduction in levodopa dosage. Mentation, behaviour and mood [Unified Parkinson's Disease Rating Scale (UPDRS) part I], and timed walking test were not significantly improved. The extent of disability improved according to the UPDRS parts II and III but, when assessed by secondary efficacy parameters, it is unclear whether disability or the severity of disease improved. No significant differences were observed in patients randomised to pramipexole or bromocriptine according to a secondary hypothesis in a prospective study in which both drugs were better than placebo. Some quality-of-life measures improved with active treatment relative to placebo. Further studies comparing pramipexole with other dopamine agonists and levodopa in patients with early and advanced Parkinson's disease would be useful. In pramipexole recipients with early disease, the most commonly experienced adverse events were nausea, dizziness, somnolence, insomnia, constipation, asthenia and hallucinations. The most commonly reported adverse events in pramipexole recipients with advanced disease were orthostatic hypotension, dyskinesias, extrapyramidal syndrome (defined as a worsening of the Parkinson's disease), dizziness, hallucinations, accidental injury, dream abnormalities, confusion, constipation, asthenia, somnolence, dystonia, gait abnormality, hypertonia, dry mouth, amnesia and urinary frequency. The incidence of some adverse events did not greatly differ between pramipexole and placebo recipients. CONCLUSIONS: Pramipexole is effective as adjunctive therapy to levodopa in patients with advanced Parkinson's disease. However, the potential beneficial effects of pramipexole on disease progression need to be confirmed in clinical studies. The efficacy of pramipexole monotherapy in patients with early disease has also been demonstrated, although the use of dopamine agonists in early Parkinson's disease remains controversial.

Antiparkinson Agents

Fexofenadine.

The nonsedating histamine H1 receptor antagonist fexofenadine is the active metabolite of terfenadine. It reduced the allergic response in animal models of allergy and did not prolong the QT interval (QTc) in dogs or rabbits at plasma concentrations many times higher than those seen after administration of therapeutic dosages. Similarly, relative to placebo, fexofenadine did not affect mean QTc in patients given dosages of up to 480 mg/day for 2 weeks or in volunteers who received up to 800 mg/day for 6 days or 240 mg/day for 12 months. In a double-blind clinical trial, oral fexofenadine 120 or 180mg once daily controlled symptoms in patients with seasonal allergic rhinitis as effectively as cetirizine. Other double-blind clinical trials showed that fexofenadine 40 to 240mg twice daily was significantly more effective than placebo. Fexofenadine 180 or 240mg once daily was significantly more effective than placebo in patients with chronic idiopathic urticaria. The drug was well tolerated in these clinical trials, with an adverse event profile similar to that seen with placebo. The most common adverse events were headache, throat irritation, viral infection, nausea, dysmenorrhoea, drowsiness, dyspepsia and fatigue.

Animals

Sumatriptan. An updated review of its use in migraine.

UNLABELLED: Sumatriptan is a selective agonist at serotonin 5-HT1-like receptors, including 5-HT1B/1D subtypes. It is an effective treatment for acute migraine attacks and the injectable form has also shown efficacy in the treatment of cluster headaches. In placebo-controlled clinical trials, sumatriptan, administered subcutaneously, orally, intranasally or rectally was significantly more effective than placebo in relieving migraine headache and in producing resolution or reduction of other symptoms associated with migraine, including nausea, photophobia and phonophobia. Improvements in clinical disability were also significantly greater after sumatriptan than after placebo. Headache recurred in 21 to 57% of patients who received oral or subcutaneous sumatriptan, but most patients responded to a second dose of the drug. Results of comparative trials showed that subcutaneous sumatriptan 6 mg was significantly more effective than either patients' usual antimigraine treatments or intranasal dihydroergotamine mesylate 1 mg in relieving migraine headache. Subcutaneous sumatriptan 6 mg and subcutaneous dihydroergotamine mesylate 1 mg provided similarly effective migraine relief, but the headache recurrence rate was significantly higher after sumatriptan than after this formulation of dihydroergotamine mesylate. Response rates achieved after oral sumatriptan were similar to those reported after treatment with oral naratriptan, rizatriptan or lysine acetylsalicylate plus metoclopramide. Treatment of acute migraine attacks with oral or subcutaneous sumatriptan leads to less loss of workplace productivity than other antimigraine therapies. Several pharmacoeconomic analyses showed that gains in workplace productivity in sumatriptan recipients ranged from 12.1 to 89.8 hours per patient per year. Significant improvements from baseline in overall health-related quality-of-life scores were also experienced by sumatriptan recipients. Sumatriptan is generally well tolerated. Nausea, vomiting, malaise and fatigue are the most common adverse events with oral sumatriptan. Injection site reactions occur in 10 to 40% of patients receiving the drug subcutaneously. A bitter taste at the back of the mouth occurs frequently after intranasal administration. Serious adverse events occur in about 0.14% of patients with migraine treated with sumatriptan. As the drug is associated with the rare development of cardiovascular effects, it is contraindicated in patients with a history of cardiovascular disease. CONCLUSIONS: Despite its relatively high acquisition cost, reductions in lost workplace productivity experienced by patients treated with sumatriptan may result in savings in the overall cost of migraine to society. Thus, sumatriptan is a useful first- or second-line treatment option for patients with moderate or severe migraine.

Administration, Intranasal

Montelukast.

Montelukast is a selective antagonist of the leukotriene D4 (LTD4) receptor. In patients with asthma, montelukast 5 to 250 mg/day attenuated LTD4-induced bronchoconstriction and, at a dosage of 10 mg, significantly reduced early and late airway response to allergen (dust mite extract) relative to placebo. In studies evaluating the effects of various dosages of montelukast on exercise-induced bronchoconstriction the optimal dose of the drug was found to be 10 mg. Montelukast 10 mg/day controlled asthma significantly more effectively than placebo in a 3-month randomised double-blind study. In a 9-month open extension of this trial, during which patients were randomised to treatment with montelukast 10 mg/day or beclomethasone (approximately 400 micrograms/day), daytime symptom score and beta-agonist use decreased to a similar extent in each group. In a further study, treatment with montelukast 10 mg/day permitted clinically significant tapering of corticosteroid dosage in patients with stable asthma. Montelukast (5 mg/day) has also demonstrated efficacy in childhood asthma. The tolerability profile of montelukast was similar to that of placebo in placebo-controlled clinical trials in adults and children; the most common adverse event was headache.

Acetates

Telmisartan.

Telmisartan is a nonpeptide angiotensin II receptor antagonist which selectively and insurmountably inhibits the angiotensin II AT1 receptor subtype without affecting other receptor systems involved in cardiovascular regulation. Oral telmisartan dose-dependently reduced blood pressure (BP) in various animal models of hypertension. In transgenic rats, telmisartan reduced cardiac hypertrophy and glomerulosclerosis. When administered at dosages of 40 to 160 mg once daily to patients with mild to moderate hypertension, telmisartan significantly reduced systolic and diastolic BP compared with placebo and was at least as effective as atenolol 50 or 100 mg and lisinopril 10 to 40 mg. One study showed telmisartan 80 mg/day to be more effective than enalapril 20 mg/day. In 2 studies that used ambulatory BP monitoring, once daily telmisartan provided better control of diastolic BP for the full dosing interval than losartan potassium 50 mg or amlodipine 5 or 10 mg. In a single study in patients with severe hypertension, a telmisartan-based regimen had antihypertensive efficacy similar to that of an enalapril-based regimen. Telmisartan had a tolerability profile similar to that of placebo in clinical studies.

Angiotensin Receptor Antagonists

Theophylline. A review of its potential steroid sparing effects in asthma.

UNLABELLED: Theophylline is generally considered to be a bronchodilatory drug. However, recent pharmacodynamic studies indicate that it has anti-inflammatory effects. It reduced eosinophil survival rates in vitro, and reduced eosinophil accumulation in bronchial tissue in patients with atopic asthma. Theophylline has also been shown to reduce T cell proliferation and accumulation. These changes were mirrored by improved pulmonary function in patients with asthma in studies that evaluated this parameter. Three randomised double-blind studies have evaluated the potential role of theophylline as an anti-inflammatory treatment in patients with asthma not controlled by low doses of inhaled corticosteroids. Patients were randomised to receive low dose theophylline (400 to 750 mg daily) plus low dose inhaled corticosteroids, or an increased dose of inhaled corticosteroids. Clinical pulmonary function improved to the same or a greater extent in patients who received low dose inhaled corticosteroids plus theophylline than in those treated with high dose inhaled corticosteroids plus placebo. Where reported, the dosages of theophylline used in these studies resulted in serum theophylline concentrations of approximately 9 to 10 mg/L. Approximate monthly costs were provided in one study: these were $60 (year and currency not specified) for theophylline plus budesonide 800 micrograms/day, compared with $100 for budesonide 1600 micrograms/day, and $155 for a regimen of budesonide 800 micrograms/day and salmeterol 100 micrograms/day. CONCLUSIONS: Low dose theophylline has been shown to reduce requirements for inhaled corticosteroid therapy in patients with asthma and may reduce overall treatment costs.

Adrenal Cortex Hormones

Lisinopril. A review of its pharmacology and clinical efficacy in elderly patients.

Lisinopril, the lysine analogue of enalaprilat, is a long-acting angiotensin converting enzyme (ACE) inhibitor which is administered once daily by mouth. The efficacy of lisinopril in reducing blood pressure is well established in younger populations, and many trials now show it to be effective in lowering blood pressure in elderly patients with hypertension. In comparative and non-comparative clinical trials, 68.2 to 89.1% of elderly patients responded (diastolic pressure < or = 90 mm Hg) to > or = 8 weeks' lisinopril treatment. Age-related differences in antihypertensive efficacy do not appear to be clinically significant, and dosages effective in elderly patients tend to range from 2.5 to 40 mg/day. Dosages usually need to be lower in patients with significant renal impairment. In congestive heart failure, lisinopril 2.5 to 20 mg/day increases exercise duration, improves left ventricular ejection fraction and has no significant effect on ventricular ectopic beats. It is similar in efficacy to enalapril and digoxin and similar or superior to captopril on most end-points. Data from the GISSI-3 post-myocardial infarction trial show that lisinopril reduced mortality and left ventricular dysfunction when given for 42 days starting within 24 hours of the onset of infarction symptoms. Results at 6 weeks and 6 months were similar in elderly and younger patients. Elderly patients, however, among other subgroups, exhibited a strong reduction in risk of low ejection fraction after treatment (-25.5%). Economic studies suggest that lisinopril is cost saving compared with other ACE inhibitors in some markets. When given according to the GISSI-3 protocol, lisinopril appears to be one of the less expensive of the successful ACE inhibitor regimens for acute myocardial infarction. In other trials, patients with diabetic nephropathy and hypertension improved or did not deteriorate during lisinopril treatment. Blood pressure was controlled and reductions or trends towards reductions in albuminuria were observed. These reductions were similar to those in diltiazem, nifedipine and verapamil recipients, and greater than those in patients receiving atenolol. Lisinopril appears to reduce mortality in diabetic patients after myocardial infarction and may also improve neuropathy associated with diabetes. Lisinopril is well tolerated and the profile of adverse events seen is typical of ACE inhibitors as a class. There is a tendency for more elderly than younger patients to discontinue treatment, but this trend is not clearly related to the incidence of adverse events in these age groups. Drug interactions occur with few other agents and are usually clinically significant only between lisinopril and either diuretics or lithium. Lisinopril is, thus, an effective treatment for elderly patients with hypertension, congestive heart failure and acute myocardial infarction and has shown promising benefits in patients with diabetic nephropathy.

Aged

Sparfloxacin. A review of its antibacterial activity, pharmacokinetic properties, clinical efficacy and tolerability in lower respiratory tract infections.

Sparfloxacin is a fluoroquinolone antibacterial agent with activity against a broad range of Gram-negative and Gram-positive organisms including Streptococcus pneumoniae, one of the main pathogens in community-acquired pneumonia. In this infection, sparfloxacin has shown efficacy similar to that of amoxicillin, erythromycin, roxithromycin, amoxicillin/clavulanic acid and amoxicillin plus ofloxacin, producing clinical cure rates of 80 to 84% assessed by intention-to-treat analyses in European or multinational trials. US studies showed similar results for sparfloxacin to those for erythromycin and cefaclor. Sparfloxacin was also as effective as all other comparator drugs in patients with other lower respiratory tract infections, usually acute exacerbations of chronic obstructive pulmonary disease (COPD). The profile of adverse effects for sparfloxacin is generally similar to that of other quinolones: gastrointestinal discomfort and CNS effects are the most common in clinical trials. Sparfloxacin causes fewer gastrointestinal disturbances than agents such as amoxicillin and erythromycin and doses not interact with theophylline, an important consideration when treating patients with respiratory disease. Its long elimination half-life permits once-daily dosage regimens. On the other hand, there are infrequent reports of prolonged QTc interval (3% increase) during sparfloxacin therapy. Photosensitivity occurs more frequently than with the other fluoroquinolones (2% of patients in an ongoing postmarketing study and 7.9% of those in US trials), and requires ongoing surveillance. In summary, the good activity of sparfloxacin against S. pneumoniae and other respiratory pathogens supports its use in lower respiratory tract infections, particularly community-acquired pneumonia. Its profile of good efficacy, once-daily dosage, good gastrointestinal tolerability and lack of interaction with theophylline are advantageous, but clinicians and patients must be alert to the possibility of photosensitivity reactions. On this basis, sparfloxacin, when appropriately prescribed, can provide the clinician with a useful alternative treatment option for these common infections.

Animals

Fludarabine. An update of its pharmacology and use in the treatment of haematological malignancies.

Fludarabine is an antineoplastic agent which has been studied in patients with a variety of lymphoproliferative malignancies. Clinical evidence from comparative studies in chronic lymphocytic leukaemia (CLL) suggests that fludarabine is at least as effective as CAP (cyclophosphamide, doxorubicin and prednisone) or CHOP (cyclophosphamide, vincristine, doxorubicin and prednisone) in previously treated or chemotherapy-naive patients and significantly more effective than chlorambucil in terms of response rate and duration and survival in chemotherapy-naive patients. Promising results have also been reported with fludarabine-based combination therapy in the treatment of patients with CLL. In addition, sequential therapy with fludarabine and cytarabine has demonstrated good efficacy in the treatment of acute leukaemias, as has fludarabine monotherapy and combination therapy in low grade non-Hodgkin's lymphoma. A favourable cytoreductive response has been reported in patients with lymphoplasmacytoid lymphoma and in a smaller number of patients with cutaneous T cell lymphomas, CLL of T cell origin or prolymphocytic leukaemia. Recent data also support the use of fludarabine, either as a component of a nonmyeloablative conditioning regimen or in the attainment of minimal residual disease, in patients undergoing peripheral blood stem cell or bone marrow transplantation. The tolerability profile of fludarabine is similar to that of CAP, with the most common adverse events being granulocytopenia, thrombocytopenia, anaemia and infection. Alopecia and nausea/vomiting appear to be less frequent with fludarabine therapy than with CAP although the development of immune cytopenias is more frequent with fludarabine. Severe neurotoxicity has been reported with fludarabine but this is mostly confined to the use of high doses. Clinical experience therefore indicates that fludarabine is an effective and generally well-tolerated antineoplastic agent for the second-line treatment of advanced CLL. Recent data from comparative studies also support the earlier use of fludarabine in the treatment of chemotherapy-naive patients with CLL. Furthermore, results of available studies are increasingly highlighting an important future role for fludarabine in the treatment of acute leukaemias and low grade NHL and possibly other lymphoproliferative disorders, particularly when used as a component of combination chemotherapy.

Antineoplastic Agents

Troglitazone.

Troglitazone decreases insulin resistance (improves insulin sensitivity), which results in reduced plasma glucose and insulin levels in patients with non-insulin-dependent diabetes mellitus (NIDDM). Risk factors for cardiovascular disease such as elevated proinsulin and triglyceride levels are also reduced by troglitazone. In clinical trials, troglitazone 200 to 800 mg daily (alone or in combination with other oral antidiabetic agents or insulin) reduced plasma or serum glucose levels and glycosylated haemoglobin compared with both baseline and placebo in patients with NIDDM refractory to other oral antidiabetic agents (usually sulphonylureas). Troglitazone was generally well tolerated in clinical trials. In patients in the US, the incidence of adverse events in troglitazone recipients was similar to that in placebo recipients.

Animals

Valsartan. A review of its pharmacology and therapeutic use in essential hypertension.

Valsartan competitively and selectively inhibits the actions of angiotensin II at the AT1 receptor subtype which is responsible for most of the known effects of angiotensin II. In clinical trials in patients with mild to moderate essential hypertension valsartan was as effective as losartan, lisinopril, enalapril, amlodipine and hydrochlorothiazide. Addition of the latter reduced blood pressure in patients who did not respond sufficiently to valsartan monotherapy. Preliminary data also suggest valsartan may be effective in patients with severe essential hypertension. The drug was as effective as lisinopril as treatment for mild to moderate essential hypertension in patients with renal insufficiency and did not worsen renal function. Headache, dizziness and fatigue were the most common adverse events in placebo-controlled studies; the incidence of these adverse events was not significantly different between placebo and valsartan recipients. Compared with ACE inhibitors, valsartan was associated with a significantly lower incidence of dry cough. Thus, valsartan is an effective treatment for mild to moderate essential hypertension and may be particularly useful in patients who experience persistent cough during ACE inhibitor therapy.

Antihypertensive Agents

Ibutilide. A review of its pharmacological properties and clinical potential in the acute management of atrial flutter and fibrillation.

Ibutilide is the first 'pure' class III antiarrhythmic drug to become available. Its predominant action is prolongation of the myocardial action potential duration. This appears to be achieved by a unique ionic mechanism of action that involves activation of a late inward sodium current and possibly blockade of the rapidly activating component of the cardiac delayed rectifier potassium current. Intravenous ibutilide 0.01 to 0.025 mg/kg or 1 to 2 mg successfully converted atrial flutter or fibrillation to sinus rhythm in 33 to 49% of patients in 2 placebo-controlled trials involving 439 patients with sustained arrhythmia. In a third trial in 300 patients who developed atrial flutter or fibrillation after cardiac surgery, ibutilide 2 mg successfully converted the arrhythmia in 57% of patients. The mean times to conversion were < or = 30 minutes in these trials. In 3 comparative trials, ibutilide was significantly more effective than racemic sotalol or procainamide in terminating atrial flutter or fibrillation. The pretreatment duration of the arrhythmia is an important predictor of the success of ibutilide treatment; the greatest conversion rates are achieved when the arrhythmia is of recent onset (i.e. < or = 30 days' duration). Ibutilide is more effective in terminating atrial flutter than atrial fibrillation. Adverse events associated with ibutilide are predominantly cardiovascular. Sustained polymorphic ventricular tachycardia developed in 1.7%, and non-sustained polymorphic ventricular tachycardia in 2.7%, of 586 patients treated with ibutilide in clinical trials. However, no proarrhythmia-related deaths have been reported with the use of ibutilide. The drug has minimal haemodynamic effects and is associated with few noncardiovascular adverse events. Thus, ibutilide is a useful agent for the pharmacological cardioversion of recent-onset atrial fibrillation or flutter, provided that adequate steps are taken to monitor for proarrhythmic events. The drug causes few noncardiovascular adverse events and has minimal haemodynamic effects. Furthermore, it appears to be more effective than procainamide (especially in patients with atrial flutter) and racemic sotalol.

Anti-Arrhythmia Agents

Fenoldopam: a review of its pharmacodynamic and pharmacokinetic properties and intravenous clinical potential in the management of hypertensive urgencies and emergencies.

Fenoldopam is a dopamine agonist that causes peripheral vasodilation via stimulation of dopamine 1 (D1) receptors. The efficacy of an intravenous infusion of fenoldopam in decreasing blood pressure in patients with a hypertensive urgency, including patients who developed hypertension after coronary artery bypass graft surgery, and in a small number of patients with hypertensive emergency, is similar to that of sodium nitroprusside. However, unlike sodium nitroprusside, fenoldopam also increases renal blood flow and causes diuresis and natriuresis. There is no evidence of rebound hypertension after stopping the infusion. As the tolerability profile of fenoldopam is generally similar to that of sodium nitroprusside, fenoldopam appears to be an effective alternative to sodium nitroprusside in the immediate treatment of patients who develop severe hypertension and in whom oral treatment is not practical. Fenoldopam may be particularly useful in patients who develop hypertension after coronary artery bypass graft surgery, but further studies are required to confirm its role in hypertensive emergency.

Antihypertensive Agents