Phentermine/Topiramate

DEA Class;  Rx

Common Brand Names; Qsymia

Hypersensitivity or idiosyncrasy to topiramate or sympathomimetic amines

Pregnancy

Glaucoma

Hyperthyroidism

Taking or within 14 days of stopping MAOIs (risk hypertensive crisis)

• Paresthesia (4.2-19.9%)
• Dry mouth (6.7-19.1%)
• Constipation (7.9-16.1%)
• URI (12.2-15.8%)
• Metabolic acidosis (6.4-12.8%)
• Nasopharyngitis (9.4-12.5%)
• Headache (7-10.6%)
• Insomnia (5-9.4%)
• Dysgeusia (1.3-9.4%)
• Dizziness (2.9-8.6%)
• Increased serum creatinine (2.1-8.4%)
• Sinusitis (6.8-7.8%)
• Nausea (3.6-7.2%)
• Bronchitis (4.4-6.7%)
• Back pain (5.4-6.6%)
• Diarrhea (5-6.4%)
• Blurred vision (4-6.3%)
• Fatigue (4.4-5.9%)
• UTI (3.3-5.2%)
• Hypokalemia (persistent) (0.4-4.9%)
• Cough (3.3-4.8%)
• Depression (2.8-4.3%)
• Anxiety (1.8-4.1%)
• Irritability (1.7-3.7%)
• Alopecia (1.7-3.7%)
• Hypoesthesia (0.8-3.7%)
• Disturbance in attention (0.4-3.5%)
• GERD (0.8-3.2%)
• Extremity pain (2.1-3%)
• Musculoskeletal pain (0.8-3%)
• Muscle spasms (2.8-2.9%)
• Dyspepsia (2.1-2.8%)
• Sinus congestion (2-2.6%)
• Rash (1.7-2.6%)
• Pharyngeal pain (1.2-2.5%)
• Dry eye (0.8-2.5%)
• Gastroenteritis (0.8-2.5%)
• Hypokalemia (acute) (0.4-2.5%)
• Palpitations (0.8-2.4%)
• Eye pain (2.1-2.2%)
• Neck pain (1.2-2.2%)
• Oral paresthesia (0.2-2.2%)
• Decreased appetite (1.5-2.1%)
• Nephrolithiasis (0.2-1.2%)
• Dysmenorrhea (0.4-2.1%)
• Chest discomfort (0.2-2.1%)
• Thirst (1.8-2%)
• Nasal congestion (1.2-2%)

May cause fetal harm

May increase resting heart rate (HR) up to 20 bpm; reduce dose or discontinue use with sustained increase in resting HR; caution in patients with history of cardiac or cerebrovascular disease

Antiepileptic drugs (AEDs), including topiramate, increase the risk of suicidal thoughts or behavior; discontinue if suicidal thoughts or behaviors emerge; avoid in patients with history of suicidal attempts or active suicidal ideation

Can cause mood disorders, including depression, anxiety, and insomnia

Cognitive dysfunction (eg, concentration/attention impairment, difficulty with memory, and speech or language problems, particularly word-finding difficulties); rapid titration or high initial doses associated with higher rates cognitive difficulties

Associated with reduction in height velocity (centimeters of height gained per year) in obese pediatric patients 12-17 years of age; monitor height velocity in pediatric patients receiving therapy; consider dosage reduction or discontinuation of therapy if pediatric patients are not growing or gaining height as expected

Phentermine/topiramate associated with increased serum creatinine that reflects a decreased renal function

Adjust antidiabetic drugs according to patient’s blood glucose as patient loses weight

As patient loses weight, adjust antihypertensive medications to avoid risk of hypotension

Avoid abrupt withdrawal of topiramate (particularly at higher doses); associated with seizures in patients with history of seizures or epilepsy

Kidney stone formation reported; topiramate inhibits carbonic anhydrase activity and promotes kidney stone formation by reducing urinary citrate excretion and increasing urine pH; risk may increase further with ketogenic diet; patients on a ketogenic diet may be at increased risk for kidney stone formation; Increased ratio of urinary calcium/citrate increases risk of kidney stones and/or nephrocalcinosis

Contraindicated in pregnant patients; use can cause fetal harm and weight loss offers no clear clinical benefit to a pregnant patient

Drug components are present in human milk; there are no data on effects of topiramate and phentermine on milk production; diarrhea and somnolence reported in breastfed infants with maternal use of topiramate; there are no data on effects of phentermine in breastfed infants