Metformin Vs. Topamax: Drug Comparison

Metformin is an oral medication commonly prescribed to manage blood sugar levels in individuals with type 2 diabetes. It works by decreasing glucose production in the liver, improving the body's sensitivity to insulin, and reducing the amount of sugar absorbed by the intestines. Metformin is often used as a first-line treatment due to its efficacy, safety profile, and additional benefits, such as weight stabilization and low risk of low blood sugar. Common side effects include gastrointestinal issues like nausea, diarrhea, and abdominal discomfort.

Topamax^® (topiramate) is an anticonvulsant medication used to treat seizures and prevent migraines by stabilizing electrical activity in the brain and reducing abnormal brain cell firing. Its FDA-approved indications include the treatment of epilepsy for partial onset or generalized tonic-clonic seizures and migraine prevention in adults and adolescents (12 and older). Topamax is available in tablet and sprinkle capsule forms, typically taken once or twice daily. Common side effects include dizziness, paresthesia, fatigue, weight loss, and trouble concentrating, and it carries a warning for increased risk of metabolic acidosis and kidney stones.

Biguinide

Anticonvulsant

Metformin hydrochloride tablets are indicated:

• As an adjunct to diet and exercise to improve glycemic control in adults and pediatric patients 10 years of age and older with type 2 diabetes mellitus

Topamax (topiramate) is indicated for:

• Epilepsy: initial monotherapy for the treatment of partial-onset or primary generalized tonic-clonic seizures in patients 2 years of age and older; adjunctive therapy for the treatment of partial-onset seizures, primary generalized tonic-clonic seizures, or seizures associated with Lennox-Gastaut syndrome in patients 2 years of age and older

• Preventive treatment of migraine in patients 12 years of age and older

• Typically taken orally once, twice, or three times daily

• Comes in 500 mg, 850 mg, and 1,000 mg tablets

• Typically taken orally with dosing based on indication and age group

• Comes in 25 mg, 50 mg, 100 mg, and 200 mg tablets and 15 mg and 25 mg sprinkle capsules

For metformin hydrochloride, the most common adverse reactions (>5%) are:

• Diarrhea

• Nausea/vomiting

• Flatulence

• Weakness

• Indigestion

• Abdominal discomfort

• Headache

Epilepsy: Most common (≥10% more frequent than placebo or low-dose Topamax) adverse reactions in adult and pediatric patients were:

• Tingling

• Anorexia

• Weight loss

• Speech disorders/Related speech problems

• Fatigue

• Dizziness

• Sleepiness

• Nervousness

• Slowing down of physical and mental activities

• Abnormal vision

• Fever

Migraine: Most common (≥5% more frequent than placebo) adverse reactions in adult and pediatric patients were:

• Tingling

• Anorexia

• Weight loss

• Difficulty with memory

• Taste perversion

• Diarrhea

• Loss of sensation

• Nausea

• Abdominal pain

• Upper respiratory tract infection

• Severe renal impairment (eGFR below 30 mL/min/1.73 m²)

• Hypersensitivity to metformin

• Acute or chronic metabolic acidosis, including diabetic ketoacidosis, with or without coma

• Drug interactions: Carbonic anhydrase inhibitors, drugs that reduce metformin clearance (such as ranolazine, vandetanib, dolutegravir, and cimetidine), alcohol

• Drug interactions: contraceptives, lithium

• Lactic acidosis: See Boxed Warning

• Vitamin B12 deficiency: Metformin may lower vitamin B12 levels

• Low blood sugar with concomitant use with insulin and insulin secretagogues

• Females and males of reproductive potential: Potential for an unintended pregnancy

• Acute myopia and secondary angle closure glaucoma

• Visual field defects

• Oligohidrosis and hyperthermia

• Metabolic acidosis

• Suicidal behavior and ideation

• Cognitive/Neuropsychiatric adverse reactions

• Fetal toxicity

• Withdrawal of AEDs

• Decrease in bone mineral density

• Negative effects on growth (height and weight)

• Serious skin reactions

• Hyperammonemia/Encephalopathy

• Kidney stones

• Hypothermia has been reported with and without hyperammonemia during topiramate treatment with concomitant valproic acid use

WARNING: LACTIC ACIDOSIS

Postmarketing cases of metformin-associated lactic acidosis have resulted in death, hypothermia, hypotension, and resistant bradyarrhythmias. Symptoms included malaise, myalgias, respiratory distress, somnolence, and abdominal pain. Laboratory abnormalities included elevated blood lactate levels, anion gap acidosis, increased lactate/pyruvate ratio; and metformin plasma levels generally >5 mcg/mL.

Risk factors include renal impairment, concomitant use of certain drugs, age >65 years old, radiological studies with contrast, surgery and other procedures, hypoxic states, excessive alcohol intake, and hepatic impairment. Steps to reduce the risk of and manage metformin-associated lactic acidosis in these high risk groups are provided in the Full Prescribing Information.

If lactic acidosis is suspected, discontinue metformin hydrochloride tablets and institute general supportive measures in a hospital setting. Prompt hemodialysis is recommended.

*This information is from the metformin hydrochloride label used by Epic Pharma, LLC. See the Full Prescribing Information for more complete information. Metformin may also be the active ingredient in other medications, and this information may not be accurate for all medications that include the active ingredient metformin.

*This information is from the label for brand name Topamax^®. See the Full Prescribing Information for more complete information. Topiramate, the active ingredient in Topamax, may also be the active ingredient in other medications, and this information may not be accurate for all medications that include the active ingredient topiramate.