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Actos and Lactic Acidosis

The potential side effects of Actos are well known, and may include bone fractures, heart problems, and bladder cancer. But what many people do not know is that Actos has also been linked to lactic acidosis. This life-threatening condition – that is fatal in about 50 percent of cases – is associated with metformin, an ingredient in the combination Actos medications Actoplus met and Actoplus metXR.

What is lactic acidosis?Actos and Lactic Acidosis

Lactic acid, or lactate, is a natural substance and metabolic byproduct. A build-up of lactic acid is most commonly associated with strenuous exercise, which causes the body’s cells to suffer oxygen deficiency. You’re probably familiar with this symptom: sore, strained muscles after a long walk or uncharacteristic exercise. This form of lactic acidosis, which is known as Type A, is normal and does not represent any serious health risk.

Type B lactic acidosis, on the other hand, can be very dangerous. There are three sub-categories, all of which result in oxygen deficiencies due to a build-up of lactic acid: B1 lactic acidosis is caused by AIDS, leukemia, lymphoma, or ketoacidosis; B2 lactic acidosis occurs due to toxins or certain drugs, including HIV medications, excessive alcohol, cyanide, and metformin (an ingredient in Actoplus met and Actoplus metXR); and B3 lactic acidosis is linked to congenital enzyme defects.

Symptoms of lactic acidosis

The most common cause of lactic acidosis is strenuous exercise, or unaccustomed types or levels of physical activity. However, aside from the discomfort of sore muscles, this type of lactic acid buildup is harmless.

Type B lactic acidosis is very hazardous – it’s deadly in 50 percent of untreated cases. The danger lies in the severity of its symptoms. Be aware that the symptoms of lactic acidosis can start out mild (usually in the first 24 hours), but can deteriorate into the danger zone very quickly.

Signs and symptoms of Type B lactic acidosis often include:

  • Anemia
  • Irregular heartbeat
  • Nausea
  • Rapid breathing
  • Stomach pain
  • Tiredness or weakness
  • Very low blood pressure

Certain pre-existing conditions, habits and Type 2 diabetes medications can increase your risk of developing life-threatening Type B lactic acidosis. These include:

  • AIDS
  • Congestive heart failure
  • High alcohol consumption
  • Kidney insufficiency
  • Liver dysfunction or failure
  • Metformin, a diabetes type 2 treatment contained in Actoplus met and Actoplus metXR
  • Surgery

Link between Actos and lactic acidosis

Two types of diabetes drugs, phenformin and buformin, have been banned in the United States due to their strong link to lactic acidosis. A related drug, however, is still available: Metformin is also a type 2 diabetes treatment, and is also linked to lactic acidosis. Metformin inhibits the liver’s ability to produce sugar and therefore to filter lactic acid, thus increasing a patient’s risk of lactic acid buildup, or lactic acidosis. Metformin is still legal in the U.S., but currently carries a black-box warning for the fatal condition.

Two Actos medications, Actoplus met and Actoplus metXR, are a blend of Actos and metformin. Both have been associated with incidents of lactic acidosis. Actos alone is not mixed with metformin, so lactic acidosis is not a recognized side effect of Actos. However, Actos may be linked to diabetic ketoacidosis (DKA) – a precursor for lactic acidosis.

All patients taking medications with metformin should have their electrolyte levels checked within 14 days of beginning treatment; this test will help your doctor evaluate your risk for the deadly form of lactic acidosis.

FDA issues lactic acidosis warning

In May 2002, the FDA issued a review of metformin hydrochloride tablets. The communication reviewed several contraindications for metformin, including people with renal disease, congestive heart failure and diabetic ketoacidosis.

At the time, the FDA also stated, “Lactic acidosis is a rare, but serious, metabolic complication that can occur due to metformin accumulation during treatment with metformin; when it occurs, it is fatal in approximately 50% of cases. Lactic acidosis may also occur in association with a number of pathophysiologic conditions, including diabetes mellitus… The reported incidence of lactic acidosis is very low… and have occurred primarily in diabetic patients with significant renal insufficiency… The risk of lactic acidosis increases with the degree of renal dysfunction and the patient’s age. The risk of lactic acidosis may, therefore, be significantly decreased by regular monitoring of renal function in patients taking metformin and by use of the minimum effective dose of metformin… The onset of lactic acidosis often is subtle… The patient and the patient’s physician must be aware of the possible importance of such symptoms.”

Lactic acidosis not a common charge in Actos lawsuits

Thankfully, the relationship between metformin and lactic acidosis is well understood. This means that doctors can inform patients of the risk, and together they can work to eliminate the danger of this potentially fatal condition. Furthermore, metformin is only present in Actoplus met and Actoplus metXR. For these reasons, lactic acidosis is not a common allegation in Actos lawsuits.