A new class of drug to treat diabetes

Published in The Hindu on October 25, 2007

Two years after the drug was approved by the U.S. Food and Drug Administration, diabetics (Type II) in India have the choice of a new class of drug that would help keep their disease under check.

While existing drugs work to keep blood glucose level near normal, some of the drugs do not act in response to the glucose level which peaks after a meal. The new class of drug recently launched in India by Eli Lilly — Exenatide (under the brand name Byetta) — enables the body to release insulin only in response to the level of glucose present in the blood.

Exenatide is similar in action to the naturally occurring GLP-1 hormone that is secreted by the intestine in response to food intake.

Brief half-life

“But the half-life of GLP-1 is just one-and-a-half minutes,” said Harold E. Lebovitz, Professor of Medicine, Endocrinology & Metabolism/Diabetes, State University of New York Downstate Medical Center. Prof. Lebovitz was in Chennai recently. GLP-1 has a brief half-life as it gets easily broken down by an enzyme (DPP-4).

As it is secreted in response to food intake, stimulates beta-cell secretion and contributes to satiety, many pharmaceutical companies have tried producing GLP-1 as a possible therapeutic agent. But the brief half-life of the hormone has posed a big challenge.

Unlike GLP-1, exenatide (drug byetta) is a synthetic molecule that resembles GLP-1 and hence escapes immediate destruction by the DPP-4 enzyme.

Weight reduction

“Another big advantage of exenatide is that it leads to continuous weight reduction,” said Prof. Lebovitz. “There is a 5 per cent mean weight reduction over a two-year period.” According to him, 0.5-1 kg weight reduction is seen in patients on metformin medicine. Byetta causes weight reduction as it reduces food intake by decreasing appetite and increasing satiety.

Acceptability

But if the new drug helps lose weight, it faces a big challenge of acceptance; it is not an oral medicine but an injection. Patients’ reluctance to take insulin injections when oral medicines fail to produce the desired result is well known. So how does the company intend to address this issue?

“Our view is that exenatide offers a paradigm shift in the way diabetes is treated. It’s a novel drug and has distinct advantages. There is no dose adjustment needed unlike in insulin,” said Sandeep Gupta, Chairman and Managing Director of Eli Lilly, India.

Since people on insulin can gain weight, Byetta may be an option before moving over to insulin, especially by those who are already overweight or obese.

Despite its novelty, its use as a monotherapy is not recommended.

“It may probably work as a stand alone. But we don’t know yet as no studies have been done,” said Prof. Lebovitz.

Byetta has, however, been approved for use in the U.S. and Europe in combination with metformin and/or sulphonylurea by those who are unable to control blood sugar levels by these drugs alone.

Side effects

The exenatide has other side effects as well; it causes nausea and vomitting. “It’s [nausea] seen in a significant number of people. [About] one third to start with, but [it] decreases with time, about 12-14 weeks. About 3-5 per cent of people tend to have nausea in regular therapy,” said Prof. Lebovitz.

And does Byetta ever cause hypoglycaemia? “Byetta does not increase the risk of hypoglycaemia when given alone or in combination with metformin [medicine],” said Dr. Vinod Mattoo, Medical Director of Eli Lilly India.

“But there is a [higher] risk when given along with sulphonylurea [medicine].” This is because sulphonylurea continues to act irrespective of the blood glucose levels.

“Byetta is not for every patient,” Mr. Gupta underlined. “There is also a selection of doctors for promoting it.”

He is probably right. At Rs.7,900 per month for a 10mcg injection and Rs.7,600 for a 5mcg injection, Byetta may not be affordable by many.

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