Sunday, June 24, 2012

Weight and Topamax

Weight and Topamax

We may soon see new drugs approved by the FDA to help with weight loss. 
One of these contains Topamax. The generic name for Topamax is topiramate. 
Topamax has been known for almost 10 years to promote weight loss.
Of course, Topamax is not approved by the FDA for weight loss.

Topamax is approved by the FDA for prevention of seizures and prevention of migraines. 
But when Topamax was tested for seizures, studies showed that it tended to cause weight loss. Since then multiple studies have confirmed that Topamax even in low doses tends to cause weight loss.

These early studies have been confirmed with further randomized controlled clinical trials in those with diabetes on metformin or diabetes on no other medication, those with binge eating disorder,  those with migraines and others. A controlled release form of Topamax has also  proven effective.

There does not appear to be much benefit of Topamax on weight above 200 milligrams per day and 100 milligrams works well in many studies.

As with other medications for weight loss, individual responses can vary considerably. But in most studies about 5-6% of baseline weight was lost with Topamax as compared to about 1.5% with placebo treatment. And improvement in blood pressure and blood glucose control has been seen.

Topamax can produce plenty of side effects. Most of these are related to brain function. These include problems with memory, concentration, attention, alertness, sleepiness, changes in taste and tingling feelings. These neurologic side effects depend on the dosage, the higher the Topamax dosage, the more likely the side effects. Dosage no higher than 100 milligrams seems to be tolerated best. And most patients do best with slow upward increases in dosage, starting with dosing at bedtime. Any side effects promptly go away when the Topamax is discontinued.

Topamax  also increases the risk of calcium phosphate kidney stones by reducing the ability of the kidney to excrete acid and reabsorb alkali. The urine becomes more alkaline and the blood becomes more acidic. Technically this means that Topamax produces a renal tubular acidosis. Increasing fluid intake may reduce the risk of kidney stones in those taking Topamax.

No drug for weight loss should be used during pregnancy. And topiramate can cause birth defects if  taken during pregnancy. The likelihood of cleft lip and cleft palate are increased at least two-fold if topiramate is used during pregnancy.

The combination drug Qsymia may be approved soon for weight loss. It contains both Topamax and phentermine in an extended release formulation. 

Topamax itself has beneficial weight loss effects. But as with all other conditions, there is no perfect drug.

Modifying behavior with dietary effort and exercise continues to be very important. And Topamax may help.

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