Topiramate is a widely known antiepileptic drug but currently, its uses have spread beyond that circle. Now it is a treatment for other conditions such as migraine headaches. Yet, as with any other good medication, it is also known to cause a list of adverse effects. Therefore, let us spend a couple of minutes to get a little bit of a clearer idea of this special drug; Topiramate!

What Type of Epilepsy is Treated with Topiramate?

Topiramate is a broad-spectrum anti-seizure medication that works for both focal and generalized seizures. It is approved for patients of or above two years of age. Thus, it is used in pediatric conditions such as Lennox Gastaut Syndrome and infantile spasms. 

What Other Conditions Are Treated with Topiramate?

Other than for epilepsy, Topiramate is widely used for headaches including migraine attacks, Cluster headache, and Short-lasting Unilateral Neuralgiform Attacks (SUNA). Furthermore, it works great for alcohol abuse disorder and essential tremors.

Due to its effect of reducing the appetite, it is used for weight loss and eating disorders such as Binge eating and Bulimia nervosa. However, its effect on preventing weight gain with Mood stabilizers is not very strong.

What is the Mechanism of Action of Topiramate?

Topiramate works through multiple mechanisms, favoring a more powerful action. It blocks voltage-dependent sodium channels, enhances the activity of GABA on GABA-A receptors, and antagonizes the NMDA-glutamate receptor. It is also a carbonic anhydrase inhibitor and helps cerebrospinal fluid production. 

How to Dose Topiramate?

This strictly depends on the condition and the age of the patient. In monotherapy for epilepsy, initially, we give 25 mg twice a day and after a week we increase it by 50 mg per week until we reach 200 to 400 mg per day. If we use an extended-release formulation, we can give the total quantity in one go. The target dose is lower when we use Topiramate with other drugs. For other conditions including migraine, start with 25 mg daily and then increase 25 mg per week, until the maximum dose is 50 mg twice a day.

In children, the dose is adjusted to the weight. We start with 0.5-1 mg/kg/day in two divided doses and increase weekly by 0.5-1 mg/kg/day in two divided doses. Maximum dose is 40 mg/kg/day. In the elderly, we start with lower doses and titrate slowly to achieve better tolerability.

We should increase the dose accordingly when Topiramate is used with antiepileptic drugs like Phenytoin and Carbamazepine, as they induce liver enzymes that metabolize Topiramate. We should be cautious about Topiramate toxicity in liver failure. The target dose should be reduced by 50% if the renal clearance is below 70 ml/min. If the patient is on dialysis, 50% of the target dose should be given additionally, after dialysis, as Topiramate gets filtered during the procedure.

What are the Side Effects of Topiramate?

Cognitive disturbances like difficulty in finding words and memory impairment are common adverse effects. Metabolic acidosis can lead to kidney stone formation. There is a risk of acute angle closure glaucoma during the first three months. Children are more vulnerable to developing overheating due to reduced sweating (hypohydrosis). Suicidal ideas, mood issues, anxiety, depression, and irritability are possible behavioral effects. Dizziness, fatigue, abdominal pain, nausea, and diarrhea are also common to occur. 

What is Topiramate Did not Work for Me?

Non-compliance is the major reason. It is important to take the missed doses as soon as possible unlike the anti-cholesterol or anti-hypertensive drugs. The optimum highest dose should be reached to get the targeted effect but this takes about three to six months. If it is still not responding, we can add another anti-epileptic. Surgical management is the option for "drug-resistant epilepsy". 

Are there Any Drug Interactions with Topiramate?

Topiramate is a weak liver enzyme inducer. Therefore, doses above 200mg decrease the efficacy of Oral Contraceptive Pills and lower other medications that are processed by the liver.

Can I Drive or Drink Alcohol with Topiramate? 

As Topiramate leads to dizziness and drowsiness, driving should be avoided until you get used to that. It is better to avoid alcohol also since it worsens these side effects.

How to Stop Topiramate? 

Abrupt Topiramate cessation could lead to withdrawal seizures. Therefore, we should taper off the drug over a few weeks. Yet, abrupt withdrawal is acceptable in the case of a severe allergic reaction.

Is Topiramate Safe During Pregnancy and Breastfeeding?

Topiramate is harmful to the fetus. It could lead to smaller babies and congenital malformations like cleft palate. Therefore, it is not given during pregnancy unless for a highly essential cause like being the only responding drug for epilepsy. Then, we should adjust the dose during the second and third trimesters as the drug concentration reduces significantly during this period. 

Topiramate is excreted in breast milk in small amounts. Hence, it is best to be discussed with the neurologist whether to continue the drug during lactation or not.

Conclusion

Although Topiramate is mainly a drug for epilepsy, it also treats a list of other conditions including migraine. Understanding this great medication is beneficial to obtain a better outcome.