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The Glitazones (Rosiglitazone / Pioglitazone)

• What are the Glitazones?
• What are the available preparations?
• What are the possible side effects?
• Can these tablets cause hypoglycaemia?
• How soon will they work?
• What time of the day should they be taken?
• Why can’t I take these with Insulin?
• Who should not take the Glitazones?

What are the Glitazones?

The Glitazones (or thiazolidenediones to give them their proper name) are a new class of drugs for the treatment of type 2 diabetes. They act by helping the body use the available amounts of insulin more effectively. In other words they make you more ‘sensitive’ to insulin or improve your ‘insulin sensitivity’. People with type 2 diabetes are often resistant to insulin, a phenomenon commonly referred to as ‘insulin resistance’.  This is thought to be one of the reasons for high blood sugar levels in type 2 diabetes.

What are the available preparations?

There are currently two preparations available on prescription for people with type 2 diabetes.

1. Rosiglitazone (AvandiaR Glaxo-Smith-Klein) – this is available in two strengths 4 mg and 8 mg
2. Pioglitazone (ActosR Takeda Pharmaceuticals) – available in two strengths, 15 mg and 30 mg

What are the possible side effects?

A previous drug in this class, was withdrawn from use due to serious effects on the liver. If you take rosiglitazone or pioglitazone, it is important that you have your liver function tests (blood tests) done regularly. Your doctor is likely to ask you to attend every 2 months in order to have this done.

 You should let your doctor know immediately if you have any of the following symptoms:

• Nausea or vomiting
• Severe loss of appetite
• Yellow discolouration of the eyes
• Passing dark-coloured (tea-coloured) urine

It is not uncommon to gain weight as these tablets can cause fluid retention. For this reason they may aggravate heart failure and you should not take these tablets if you are known to have heart failure. The fluid retention may give you swelling of the ankles.

You may also develop a mild anaemia, which could make you feel tired.

If you are not yet menopausal but have had subfertility due to lack of ovulation, these drugs may result in ovulation which may increase your chance of a pregnancy.

Can these tablets cause hypoglycaemia?

Usually these compounds do not cause blood sugar levels to drop below the normal, however, this may occur since you are likely to be taking other tablets in conjunction with rosiglitazone or pioglitazone.

How soon will they work?

Do not expect dramatic results. The action of these drugs usually commences within 2-3 weeks and it may take up to 8 – 12 weeks for the maximum response.

What time of the day should they be taken?

The timing of the dose is not important so long as you take them regularly.

Why can’t I take these with Insulin?

As yet, Glitazones are not licensed for use in combination with insulin. It is thought that when combined with Insulin, the glitazones may pose an increased risk of fluid retention and heart failure. Trials are currently under way and a license for combination therapy may be expected in the future.

Who should not take the Glitazones?

People with the following conditions should not take Rosiglitazone or Pioglitazone.

• Heart failure
• Active liver disease
• Type 1 diabetes
• Pregnancy

If you are not currently pregnant but are contemplating pregnancy you should discuss this with your doctor.

 

Dr Nishan Wijenaike, Consultant Physician
West Suffolk Hospital Diabetes Service
October 2002