Prescrire international
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Prescrire international · Dec 2005
Comparative StudyChemotherapy of metastatic colorectal cancer: fluorouracil plus folinic acid and irinotecan or oxaliplatin.
(1) Following the recent introduction of several new cytotoxic agents, a new look at the role of chemotherapy in metastatic colorectal cancer is needed. (2) In one clinical trial of first-line treatment, fluorouracil + folinic acid infusion, after an initial bolus (LV-5FU2 protocol), was more effective and better tolerated than bolus administration alone (Mayo Clinic protocol). (3) Five comparative trials failed to show that raltitrexed was more effective than fluorouracil + folinic acid in first-line treatment, and it has more serious adverse effects. (4) There are no comparative trials of capecitabine or tegafur + uracil versus fluorouracil + folinic acid (LV-5FU2 protocol) in first-line treatment. (5) In three comparative randomised trials involving previously untreated patients, adjunction of oxaliplatin to the fluorouracil + folinic acid combination (FOLFOX protocol) increased both tumour response rate and progression-free survival (by about 2 months), but it also caused more neuropathies, severe diarrhea and severe neutropenia. (6) In two comparative trials of first-line treatment, adjunction of irinotecan to fluorouracil + folinic acid (FOLFIRI protocol) increased the median survival time by about 3 months, to 15-17 months, but increased the incidence of diarrhea, neutropenia, serious cardiovascular disorders and severe thrombosis. (7) In second-line treatment, irinotecan is the only properly assessed drug with a positive impact, prolonging survival compared with appropriate palliative care (34 months after diagnosis, versus 27 months). (8) In one comparative trial, first-line treatment with the FOLFOX protocol, followed by the FOLFIRI protocol, resulted in the same median survival time (21 months) as the reverse sequence. (9) In practice, the first-line treatment for metastatic colorectal cancer appears to be the fluorouracil + folinic acid combination (LV-5FU2 protocol) plus either oxaliplatin (FOLFOX protocol) or irinotecan (FOLFIRI protocol). The reference second-line treatment is the FOLFIRI protocol (or the FOLFOX protocol if the FOLFIRI protocol has already been used). These treatments were associated with the longest survival in one trial.
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Prescrire international · Dec 2005
Comparative StudyPregabalin: new drug. Very similar to gabapentin.
(1) The first-line treatment for partial epilepsy is carbamazepine monotherapy; gabapentin monotherapy is an alternative, given its lower risk of drug-drug interactions. (2) The standard treatment for neuropathic pain associated with diabetes or post-herpetic neuralgia is a tricyclic antidepressant, with gabapentin as an alternative. Few drugs are available in this setting, and their efficacy is often modest. (3) Pregabalin is a GABA analogue closely related to gabapentin. Both drugs are marketed by Pfizer. ⋯ Animal studies suggest a possible risk of haemangiosarcoma, although no human cases have yet been described. (10) Pregabalin, like gabapentin, is eliminated unchanged in urine, implying a limited risk of interactions involving cytochrome P450, and suggesting that the dose should be reduced in patients with even moderate renal failure (creatinine clearance below 60 ml/min). (11) In practice, pregabalin offers nothing new for patients with partial epilepsy, for whom several other antiepileptics are available. The few available treatments for neuropathic pain have limited efficacy, and pregabalin may therefore be tried when both tricyclics and gabapentin fail. However, it is in no way certain that pregabalin is effective in such patients, and comparative trials are lacking.
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Prescrire international · Dec 2005
Comparative StudyStrontium: new drug. Postmenopausal osteoporosis: too many unknowns.
(1) Strontium ranelate is marketed in the European Union for the treatment of postmenopausal osteoporosis. Strontium, a cation closely related to calcium, was already used for this purpose in the 1950s but was abandoned because it caused bone mineralization disorders (mainly due to the high doses used at the time). (2) Strontium has only been compared with placebo: there are no clinical trials versus a diphosphonate. (3) On the basis of bone mineral density, two dose-finding studies suggested that, in women who are also taking calcium and vitamin D, the effective minimal dose of strontium is 1 g/day for primary prevention and 2 g/day for secondary prevention. (4) In secondary prevention, a randomised, double-blind trial (SOTI) involving 1649 postmenopausal women who had already had an osteoporotic fracture and were also taking calcium + vitamin D, showed that 2 g strontium daily reduced the risk of symptomatic vertebral fractures compared with placebo (11.3% versus 17.4%) after three years of treatment. (5) Another randomised, double-blind trial (TROPOS) involved 5091 women with osteoporosis of the femur. After three years of treatment with calcium, vitamin D, and either 2 g/day strontium or placebo, the risk of non vertebral osteoporotic fracture was lower in the strontium arm (10.9% versus 9.1%; relative risk 0.85, 95% confidence interval 0.71-1.01), although the difference was only just significant (p = 0.05). ⋯ Strontium can affect mental functions, and this effect needs to be quantified. Neurological and muscular adverse effects were inadequately documented, although disorders of this type were observed in animals. (8) The long-term adverse effects of strontium on bone (osteomalacia, pathological fractures, etc.) are unknown. Data from experimental studies and dialysis patients with renal failure raise the possibility of these adverse effects. (9) In practice, there are too many unknowns surrounding the potential risks of strontium while there is not enough evidence of clinical advantages over diphosphonates.
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Prescrire international · Oct 2005
Comparative StudyAngiotensin II receptor antagonists and heart failure: angiotensin-converting-enzyme inhibitors remain the first-line option.
(1) Some angiotensin-converting-enzyme inhibitors (ACE inhibitors) reduce mortality in patients with heart failure (captopril, enalapril, ramipril and trandolapril), and in patients with recent myocardial infarction and heart failure or marked left ventricular dysfunction (captopril, ramipril and trandolapril). (2) Angiotensin II receptor antagonists, otherwise known as angiotensin receptor blockers, have haemodynamic effects similar to ACE inhibitors, but differ in their mechanism of action and certain adverse effects. (3) Five clinical trials have evaluated angiotensin II receptor antagonists (candesartan, losartan and valsartan) in terms of their effect on mortality and on the risk of clinical deterioration in patients with symptomatic heart failure, but without severe renal failure, hyperkalemia or hypotension. In these trials, candesartan and valsartan were used at much higher doses than those recommended for the treatment of arterial hypertension. (4) In patients with heart failure who were not taking an angiotensin II receptor antagonist or an ACE inhibitor at enrollment, no significant difference was found between losartan and captopril in terms of mortality or the risk of clinical deterioration. (5) In patients with heart failure who had stopped taking an ACE inhibitor because of adverse effects, candesartan had no effect on mortality as compared with placebo, but it did reduce the risk of clinical deterioration (3 fewer hospitalisations per year per 100 patients). However, candesartan was associated with adverse effects such as renal failure and hyperkalemia, especially in patients who had experienced these same adverse effects while taking an ACE inhibitor. (6) In patients with heart failure who were already taking an ACE inhibitor, adjunctive candesartan or valsartan treatment did not influence mortality in comparison to the addition of a placebo. ⋯ Adding valsartan to ongoing captopril therapy did not reduce mortality or morbidity as compared with placebo, but did increase the risk of adverse effects. (12) Overall, these trials confirm the advantage of angiotensin II receptor antagonists over ACE inhibitors with respect to some adverse effects (cough, skin rash, etc.). However, the two drug classes share certain serious adverse effects such as hyperkalemia, renal failure and hypotension. In one trial, angioedema was less frequent with angiotensin II receptor antagonist therapy (one less case per 500 patients).
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Prescrire international · Oct 2005
Comparative StudyInsulin in type 2 diabetes: a useful alternative despite limited assessment based on surrogate endpoints.
(1) There are few clinical trials comparing combination therapy with a sulphonylurea and metformin after oral antidiabetic monotherapy fails to provide adequate glycaemic control. The UKPDS study suggested that this combination had a negative impact on mortality. (2) The assessment of insulin therapy in patients in whom oral antidiabetic therapy fails is based solely on surrogate endpoints: mainly HbA1c (glycated haemoglobin), bodyweight, and the frequency of hypoglycaemia. (3) In a comparative randomised trial involving patients whose glucose levels were no longer controlled by a sulphonylurea, the addition of metformin or a daily injection of insulin isophane (NPH) was similarly effective in reducing HbA1c levels. However, metformin caused less weight gain. (4) There are no randomised controlled trials comparing the addition of insulin versus a sulphonylurea when ongoing metformin monotherapy is inadequate. (5) Randomised comparative trials show that, when glycaemia is no longer controlled by a sulphonylurea plus metformin, adding a daily insulin injection is more effective in lowering HbA1c levels than the addition of acarbose and as effective as adding a glitazone. ⋯ The two strategies had a similar impact on HbA1c (-1.5% to -2.5%), but patients experienced less weight gain when the oral antidiabetics were continued and a single insulin injection was added. (8) The few available comparative trials fail to show which oral treatment (a sulphonylurea, metformin, or a combination of the two) has the best risk-benefit balance when combined with a bedtime injection of insulin isophane. (9) Insulin isophane is the first-choice insulin for combination therapy with an oral antidiabetic. In comparative trials, when combined with an oral antidiabetic, insulin glargine was no more effective than insulin isophane in terms of HbA1c levels or weight gain. Insulin glargine seems to provoke less hypoglycaemia but, in the absence of adequate follow-up, its long-term adverse effects are not known. (10) When a bedtime insulin injection plus an oral antidiabetic fail to control hyperglycaemia, indirect comparisons support the use of several daily insulin injections plus metformin, or three injections of an ultrarapid insulin analogue plus a sulphonylurea.