Oral Antidiabetic Agents - Luzimar Teixeira

Oral Antidiabetic Agents 389
obese, sedentary middle-aged patients. Failure to diabetes. We consider both well established drugs
respond rapidly (i.e. within a week or two) to an oral and recent additions to the armamentarium. For each
agent in a patient thought to be complying with the class of agents we present an outline of the mode of
dietary advice usually signals the need for early use action, pharmacokinetics, indications and contrainof
insulin. If a partial response is observed, dose dications, efficacy, safety and tolerability, current
escalation is followed by step-wise addition of com- place in management and future prospects, includplementary
drugs (figure 1). Insulin is usually re- ing role in prevention of type 2 diabetes. We have
served for patients: (i) who fail to respond adequate- grouped the drugs according to their principal mode
ly to a combination of oral agents; (ii) in whom of action: (i) those that increase insulin secretion
control deteriorates despite logical and adequate (insulin secretagogues); (ii) drugs delaying the rate
drug combinations; or (iii) for whom safety and of digestion and absorption of carbohydrates (αefficacy
considerations favour its use as the drug of glucosidase inhibitors); and (iii) those with direct
choice, for example during pregnancy, or in patients effects on insulin-responsive tissues (insulin-senwith
severe hepatic or renal impairment. [10] Several sitising agents). This sequence should not be taken
classes of oral antidiabetic agents are currently to imply a hierarchy in terms of efficacy or merit.
available, the range of options having enjoyed a The recognition that type 2 diabetes is usually a
welcome expansion in recent years. However, the progressive disease implies that drug dosages will
evidence base and clinical experience vary consider- need to be increased or therapy moved to another
ably not only between classes but also between stage in the treatment algorithm. [2,4]
drugs drawn from the same class. As a result, pre-
While this article primarily reflects current pracscribing
decisions often appear to be made on rather
tice in the UK, we have endeavoured to provide a
subjective grounds, such as familiarity with a particreview
that acknowledges important differences in
ular drug; this practice may help to explain notable
prescribing in other countries. A word about moniregional
differences in prescribing.
toring: assessing the response to antidiabetic therapy
In the remainder of this article we focus on involves periodic – generally 3- to 6-monthly –
treatment of hyperglycaemia in patients with type 2 measurement of HbA 1c . This approach, which is
Aim
Diagnosis
Procedure
Diet, exercise, weight control
and health education
Relieve symptoms,
improve glycaemic
control, enhance
quality of life
Oral agent monotherapy:
metformin, sulphonylurea, meglitinide,
thiazolidinedione 1 , acarbose
Oral agent combination therapy
(using two different classes)
Move to next stage
if there is inadequate
control of glycaemia
or inadequate relief
of symptoms
Insulin or insulin plus an oral agent
Fig. 1. An algorithm for the treatment of type 2 diabetes mellitus. The progressive hyperglycaemia in type 2 diabetes requires a steppedcare
approach with treatment being modified and added over time. Rapid progression to the next stage is recommended if the glycaemic
target is not achieved. Late introduction of combinations of oral antidiabetic agents is often a prelude to insulin treatment. 1 Note that in
Europe, thiazolidinediones and nateglinide have limited licenses. The α-glucosidase inhibitor miglitol is also available in some countries
(reproduced from Krentz and Bailey, [4] with permission from the Royal Society of Medicine Press).
© 2005 Adis Data Information BV. All rights reserved. Drugs 2005; 65 (3)