Optimising low-dose methotrexate for rheumatoid arthritis-A review.

Methotrexate at low doses (5-25 mg/week) is first-line therapy for rheumatoid arthritis. However, there is inter- and intrapatient variability in response, with contribution of variability in concentrations of active polyglutamate metabolites, associated with clinical efficacy and toxicity. Prescribing remains heterogeneous across population groups, disease states and regimens. This review examines current knowledge of dose-response of oral methotrexate in the setting of rheumatoid arthritis, and how this could help inform dosage regimens.

Why maximum tolerated dose?

A long-established approach to the pharmacological treatment of disease has been to start low and go slow. However, clinicians often prescribe up to maximum tolerated dose (MTD), especially when treating acute and more severe disease, without evidence to show that MTD is more likely to improve outcomes. Cardiovascular guidelines for some indications advocate MTD even in prevention, for example hypercholesterolaemia, without compelling evidence of better outcomes. This review explores the origins and potential problems of prescribing medications at MTD. Oral effective dose 50 (ED50) may be a useful guide for balancing efficacy and safety.

Efficacy and toxicity of antihypertensive pharmacotherapy relative to effective dose 50.

Antihypertensive drugs have usually been approved at doses near the top of their respective dose-response curves. Efficacy plateaus but adverse drug reactions (ADRs), such as falls, cerebral or renal ischaemia, increase as dose is increased, especially in older patients with comorbidities. ADRs reduce adherence and may be difficult to ascertain reliably. Higher doses have generally not been shown to reduce total mortality, which provides a summary of efficacy and safety. Weight loss and other lifestyle measures are essential and may be sufficient treatment in many young and low risk patients. Most antihypertensive drug lower systolic blood pressure by around 10 mmHg, which reduces stroke and heart failure by about a quarter. Clinical trials have not been designed to demonstrate specific blood pressure treatment thresholds and targets, which are mostly extrapolated from epidemiology. Mean population oral effective dose 50 may be the most appropriate dose at which to commence antihypertensive drugs. The dose can then be titrated up if greater efficacy is demonstrated, or lowered if ADRs develop. Lower dose combination therapy may best balance benefit and harms with fewer ADRs and additive, potentially synergistic, efficacy.

Antithrombotic dose: Some observations from published clinical trials.

The clinical doses of antithrombotics-antiplatelet and anticoagulant agents-need to balance efficacy and safety. It is not clear from the published literature how the doses currently used in clinical practice have been derived from preclinical and clinical data. There are few large randomised controlled trials (RCTs) that compare outcomes with different doses vs placebo. For newer antithrombotics, RCT doses appear to have been chosen to maximise the probability of demonstrating noninferiority when compared to established agents such as warfarin or clopidogrel. Data from RCTs show that aspirin is an effective antithrombotic at doses below 75 mg daily, and that direct oral anticoagulants reduce the risk of stroke in patients with coronary disease at doses 1/4 of those recommended in atrial fibrillation. Lower doses than those currently recommended are safer and still maintain substantial efficacy.

The pharmacodynamic and clinical trial evidence for statin dose.

Statin doses around estimated effective dose 50 (ED50) can reduce myocardial infarction by over 25% and mortality by around 10%. Being a competitive enzyme inhibitor, statin efficacy plateaus at doses that are multiples above the ED50, whilst on- and off-target adverse events increase in number and severity with increasing dose. For example, myopathy has been shown to increase by up to 29-fold and liver dysfunction by up to nine-fold as statin dose is increased. Doses of up to 40-fold ED50 have been promoted, but above five-fold ED50, for example 10 mg of atorvastatin, there is no randomized controlled clinical trial evidence that coronary mortality is lowered, or that survival is increased.

Lipid and other management to improve arterial disease and survival in end stage renal disease.

INTRODUCTION: Arterial disease is common in advancing renal failure, culminating in myocardial infarction with cardiac failure, strokes and peripheral and renal artery disease. Attention to cardiac and arterial disease may slow deterioration of renal function. Management of risk factors can reduce these sequelae. Areas covered: Modifiable risk factors for arterial disease and relevant pharmacotherapies. Expert opinion: Cardiovascular disease is the biggest killer in renal failure. Statins are viewed as essential in symptomatic coronary disease and have been shown in non-renal patients to improve survival after myocardial infarction. Cochrane recommends statins in renal failure but not in end stage renal disease or transplant patients. Large well powered clinical trials focussed specifically on renal patients failed to demonstrate cardiovascular outcome or mortality benefits of statins when compared to placebo. Other lipid lowering pharmacotherapies are weaker and adverse effects may account for the absence of net clinical benefit in non-renal patients in published clinical trials. Patients should be started on a statin after myocardial infarction, regardless of lipid levels, but the risk of adverse effects in advanced renal failure with its comorbidities predicates employing only essential doses. Optimal antihypertensive and antithrombotic pharmacotherapy are also priorities.

Cholesterol trials and mortality.

An overview of clinical trials can reveal a class effect on mortality that is not apparent from individual trials. Most large trials of lipid pharmacotherapy are not powered to detect differences in mortality and instead assess efficacy with composite cardiovascular endpoints. We illustrate the importance of all-cause mortality data by comparing survival in three different sets of the larger controlled lipid trials that underpin meta-analyses. These trials are for fibrates and statins. Fibrate treatment in five of the six main trials was associated with a decrease in survival, one fibrate trial showed a non-significant reduction in mortality that can be explained by a different target population. In secondary prevention, statin treatment increased survival in all five of the main trials, absolute mean increase ranged from 0.43% to 3.33%, the median change was 1.75%, which occurred in the largest trial. In primary prevention, statin treatment increased survival in six of the seven main trials, absolute mean change in survival ranged from -0.09% to 0.89%, median 0.49%. Composite safety endpoints are rare in these trials. The failure to address composite safety endpoints in most lipid trials precludes a balanced summary of risk-benefit when a composite has been used for efficacy. Class effects on survival provide informative summaries of the risk-benefit of lipid pharmacotherapy. We consider that the presentation of key mortality/survival data adds to existing meta-analyses to aid personal treatment decisions.

Sitagliptin and other 'gliptins'--why prescribe them?

INTRODUCTION: In 2008, the Federal Drug Administration (FDA) required all new glucose-lowering therapies to show cardiovascular safety, and this applies to the dipeptidyl peptidase (DPP)-4 inhibitors ('gliptins'). At present, there is contradictory evidence on whether the gliptins increase hospitalizations for heart failure. AREAS COVERED: This is an evaluation of the Trial Evaluating Cardiovascular Outcomes with Sitagliptin (TECOS) in high risk cardiovascular subjects with type 2 diabetes [1]. TECOS demonstrated non-inferiority for sitagliptin over placebo for the primary outcome, which was cardiovascular death, nonfatal myocardial infarction, nonfatal stroke, or hospitalization for unstable angina. There was no difference in the rate of hospitalization for heart failure between sitagliptin and placebo. EXPERT OPINION: Despite the results of TECOS, debate over the effects of sitagliptin on the rates of hospitalizations for heart failure continues with some recent studies suggesting increased rates. Recently, empagliflozin (an inhibitor of sodium-glucose cotransporter 2) has been shown to reduce cardiovascular outcomes in subjects with type 2 diabetes, including the rates of hospitalization for heart failure. In our opinion, these positive findings with empagliflozin suggest that it should be prescribed in preference to the gliptins, including sitagliptin, unless any positive cardiovascular outcomes are reported for the gliptins.

ß-adrenoceptor blockers valuable but higher doses not necessary.

ß-adrenoceptor blockers have an important role in the treatment of heart disease and are useful as an adjunct in systemic hypertension. They are often prescribed at unnecessarily high doses, near the top of the dose-response curve. Higher doses are associated with more adverse events, have not been shown to improve clinical outcomes in cardiac failure and may worsen outcome in hypertension. ß-adrenoceptor blockers can be very effective in lower doses, guided by close monitoring of heart rate and blood pressure and, when used in combination with low dose vasodilators and diuretics, give a better risk benefit profile.

Gliptins - do they increase cardiovascular risk or benefit?

INTRODUCTION: In 2008, the US FDA required all new glucose-lowering therapies to show cardiovascular safety, and this applies to the dipeptidyl peptidase-4 inhibitors ('gliptins'). AREAS COVERED: The cardiovascular safety trials of saxagliptin and alogliptin have recently been published and are the subject of this evaluation. EXPERT OPINION: The Saxagliptin Assessment of Vascular Outcomes Recorded in Patients with Diabetes Mellitus - Thrombolysis in Myocardial Infarction 53 trial and Examination of Cardiovascular Outcomes with Alogliptin versus Standard of Care were both multicentre, randomised, double-blind, placebo-controlled, Phase IV clinical trials. These trials showed that saxagliptin and alogliptin did not increase the primary end point, which was a composite of cardiovascular outcomes that did not include hospitalisations for heart failure. However, saxagliptin significantly increased hospitalisation for heart failure, which was a component of the secondary end point. The effect of alogliptin on hospitalisations for heart failure has not been reported. Neither agent improved cardiovascular outcomes. As there is no published evidence of improved outcomes with gliptins, it is unclear to us why these agents are so widely available for use. We suggest that the use of gliptins be restricted to Phase IV clinical trials until such time as cardiovascular safety and benefits/superiority are clearly established.