Drugs
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Review Comparative Study
Tranexamic acid: a review of its use in surgery and other indications.
Tranexamic acid is a synthetic derivative of the amino acid lysine that exerts its antifibrinolytic effect through the reversible blockade of lysine binding sites on plasminogen molecules. Intravenously administered tranexamic acid (most commonly 10 mg/kg followed by infusion of 1 mg/kg/hour) caused reductions relative to placebo of 29 to 54% in postoperative blood losses in patients undergoing cardiac surgery with cardiopulmonary bypass (CPB), with statistically significant reductions in transfusion requirements in some studies. Tranexamic acid had similar efficacy to aprotinin 2 x 10(6) kallikrein inhibitory units (KIU) and was superior to dipyridamole in the reduction of postoperative blood losses. Transfusion requirements were reduced significantly by 43% with tranexamic acid and by 60% with aprotinin in 1 study. Meta-analysis of 60 trials showed tranexamic acid and aprotinin, unlike epsilon-aminocaproic acid (EACA) and desmopressin, to reduce significantly the number of patients requiring allogeneic blood transfusions after cardiac surgery with CPB. Tranexamic acid was associated with reductions relative to placebo in mortality of 5 to 54% in patients with upper gastrointestinal bleeding. Meta-analysis indicated a reduction of 40%. Reductions of 34 to 57.9% versus placebo or control in mean menstrual blood loss occurred during tranexamic acid therapy in women with menorrhagia; the drug has also been used to good effect in placental bleeding, postpartum haemorrhage and conisation of the cervix. Tranexamic acid significantly reduced mean blood losses after oral surgery in patients with haemophilia and was effective as a mouthwash in dental patients receiving oral anticoagulants. Reductions in blood loss were also obtained with the use of the drug in patients undergoing orthotopic liver transplantation or transurethral prostatic surgery, and rates of rebleeding were reduced in patients with traumatic hyphaema. Clinical benefit has also been reported with tranexamic acid in patients with hereditary angioneurotic oedema. Tranexamic acid is well tolerated; nausea and diarrhoea are the most common adverse events. Increased risk of thrombosis with the drug has not been demonstrated in clinical trials. ⋯ Tranexamic acid is useful in a wide range of haemorrhagic conditions. The drug reduces postoperative blood losses and transfusion requirements in a number of types of surgery, with potential cost and tolerability advantages over aprotinin, and appears to reduce rates of mortality and urgent surgery in patients with upper gastrointestinal haemorrhage. Tranexamic acid reduces menstrual blood loss and is a possible alternative to surgery in menorrhagia, and has been used successfully to control bleeding in pregnancy.
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Sildenafil is an oral therapy for erectile dysfunction of a broad range of causes. By selectively inhibiting phosphodiesterase type 5, it allows corpus cavernosum smooth muscle to relax, potentiating erections during sexual stimulation. Blood pressure is reduced transiently by sildenafil, but more marked hypotension may occur during concurrent administration of sildenafil and organic nitrates; this combination is contraindicated. Sildenafil is rapidly absorbed, with dose-proportional peak plasma concentrations within 1 hour of administration. The elimination half-life is 3 to 5 hours. Dosages usually begin at 50mg taken when needed =1 hour before sexual activity no more than once daily. The maximum dose is 100mg when needed once daily and lower doses (e.g. 25mg) may be used in elderly patients and those with hepatic or renal impairment or receiving cytochrome P450 enzyme CYP3A4 inhibitors, such as ritonavir, saquinavir, ketoconazole, erythromycin or cimetidine. More than 3000 patients with erectile dysfunction of organic (e.g. diabetes or spinal cord injury), psychogenic or mixed origin received sildenafil 5 to 100mg or placebo in fixed- or titrated-dose trials. Sildenafil was associated with dose-related improvements in the frequency, hardness and duration of erections and in patients' abilities to achieve and maintain erections adequate for successful sexual intercourse. In titrated-dose trials, the most commonly effective doses were 50 or 100mg, although lower doses were effective in some patients. Sildenafil was significantly more effective than placebo in erectile dysfunction of all tested causes. The efficacy of sildenafil was not affected by patient age (> or < or =65 years) or by antihypertensive or antidepressant medications. The drug was effective in patients with severe erectile dysfunction. Efficacy was maintained in long term (1-year) studies. Sildenafil also appears to improve the quality of life of both patients and their sexual partners. Common adverse events associated with sildenafil were transient and mild or moderate and included headache, flushing, dyspepsia, nasal congestion and abnormal vision. Tolerability was maintained in long term (< or =1 year) studies. No serious sildenafil-related adverse events occurred in clinical trials; cardiovascular events seen in postmarketing surveillance generally occurred in patients with other known risk factors. ⋯ Sildenafil is an effective oral treatment in men with erectile dysfunction. It was significantly superior to placebo in improving erections and allowing successful penetrative sexual intercourse. Although its place in disease management is still emerging and there are contraindications to its use, if preliminary positive reports are confirmed, sildenafil will be the pre-eminent first-line therapy for erectile dysfunction.
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The NSAID diclofenac is a potent inhibitor of prostaglandin synthesis and an established antipyretic and analgesic agent. Diclofenac-potassium was developed as an immediate-release tablet with the aim of providing rapid onset of action after oral administration. This formulation has been investigated in the acute treatment of migraine. Data from available placebo-controlled clinical trials indicate that diclofenac-potassium 50 or 100mg as an immediate-release tablet is more effective than placebo and as effective as oral sumatriptan 100mg and ergotamine plus caffeine at reducing pain intensity in patients with migraine 2 hours after initial administration. Duration of pain relief is similar for the 3 drugs but onset appears to be faster with diclofenac-potassium than with oral sumatriptan or ergotamine plus caffeine. Diclofenac-potassium appears to have favourable effects on some accompanying symptoms such as nausea and vomiting. The frequency of these symptoms was significantly lower with diclofenac-potassium than with sumatriptan in 1 study, although only a few patients had vomiting at baseline. Effects on phonophobia or photophobia did not differ between diclofenac-potassium, sumatriptan and ergotamine plus caffeine. The need for rescue medication is consistently less with diclofenac-potassium than with placebo. Data are inconsistent or scarce regarding the effects of diclofenac-potassium versus placebo on other measures such as headache recurrence and working ability. Diclofenac-potassium was generally well tolerated in clinical trials in patients with migraine. Adverse events reported most frequently (abdominal pain, tiredness and fatigue and nausea) were typically mild to moderate. ⋯ Diclofenac-potassium provides rapid pain relief (within 60 to 90 minutes), is well tolerated and reduces the frequency of some of the accompanying symptoms in patients with migraine. Available trials indicate that diclofenac-potassium provides similar pain relief to sumatriptan and is at least as effective as ergotamine plus caffeine, but appears to have a greater effect on nausea and vomiting than sumatriptan and a faster onset of action than both drugs. Comparisons with other NSAIDs are lacking. Diclofenac-potassium is likely to find a role as a useful first-line option in the acute treatment of migraine.
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The pharmacological management of obesity has gained increasing attention as new weight loss treatments are approved and a significant proportion of the public strives to lose weight. Obesity is associated with a high mortality rate, multiple chronic medical conditions, and carries an enormous financial burden. Obesity is a multifactorial condition, most often due to an imbalance in energy intake and expenditure. ⋯ The effect of weight loss obtained while using pharmacotherapeutic agents on morbidity and mortality has not been established. Therefore, diet and exercise should be the focus of any weight loss programme. There is a continued need for safe and effective pharmacotherapeutic agents for the treatment of obesity.
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Etanercept, a fusion protein consisting of the extracellular ligand-binding domain of the 75kD receptor for tumour necrosis factor-alpha and the constant portion of human IgG1, is administered by subcutaneous injection and is the first specific anti-cytokine therapy approved for rheumatoid arthritis. In patients with active rheumatoid arthritis [American College of Rheumatology (ACR) functional class I to III] who had failed to respond to previous treatment with > or = 1 disease-modifying antirheumatic drug (DMARD), etanercept, alone or in combination with methotrexate, produced improvements in all components included in the ACR core set of disease activity measures. A dose-response effect was apparent with etanercept 0.25 to 16 mg/m2 twice weekly in a randomised, double-blind study in 180 patients. The mean number of swollen or tender joints at the end of the 12-week study decreased by >50% in patients treated with etanercept 16 mg/m2 twice weekly and by <25% in patients treated with placebo. In a 24-week multicentre, randomised, double-blind study in 234 patients who were not allowed to use DMARDs, etanercept 10 or 25mg twice weekly had a rapid onset of effect. Significantly more patients treated with etanercept 25mg twice weekly than placebo experienced 20 (ACR 20), 50 (ACR 50) or 70% (ACR 70) improvement in ACR criteria after 3 and 6 months. Limited evidence suggests that the therapeutic effects of etanercept are maintained for up to 2 years. Etanercept 25mg twice weekly produced significant improvement in patients receiving oral or subcutaneous methotrexate 10 to 25 mg/week in a multicentre, randomised, double-blind, placebo-controlled study. A significantly greater proportion of patients treated with etanercept plus methotrexate (71%) than placebo plus methotrexate (27%) achieved the ACR 20 criteria after 6 months. Moreover, 39 and 15% of patients treated with etanercept plus methotrexate, but no placebo plus methotrexate recipients, had achieved the ACR 50 and ACR 70 criteria at this time. Etanercept 0.4 mg/kg twice weekly reduced disease activity in a preliminary, noncomparative study in 69 children aged > or =4 years with refractory juvenile rheumatoid arthritis. Although the overall frequency of infections was similar in patients treated with etanercept or placebo, upper respiratory tract infections were more common in patients treated with etanercept (29%) than placebo (16%). Injection site reactions occurred more frequently in etanercept- than placebo-treated patients, but did not bias the results of any study. ⋯ When etanercept is administered alone or in combination with methotrexate in patients with refractory rheumatoid arthritis, significant reductions in disease activity occur within 2 weeks and are sustained for at least 6 months. Thus, etanercept appears to be particularly well suited for use in patients who fail to respond to treatment with DMARDs.