Phentermine HCl / Topiramate Capsules are a combination medication approved for chronic weight management in adults with obesity or overweight individuals with weight-related medical conditions such as hypertension, type 2 diabetes, or dyslipidemia. This dual-ingredient formulation offers a synergistic approach to weight loss by targeting both appetite suppression and satiety enhancement. The capsules are typically used alongside a reduced-calorie diet and increased physical activity to achieve sustainable weight reduction.

Phentermine is a sympathomimetic amine that suppresses appetite by increasing norepinephrine release in the brain, leading to reduced hunger signals. Topiramate, originally developed as an anticonvulsant, contributes to weight loss through several mechanisms, including appetite suppression, enhanced satiety, and altered taste perception. It affects GABA receptors, inhibits carbonic anhydrase, and modulates voltage-gated ion channels. Together, these agents reduce caloric intake more effectively than either component alone.

This medication is contraindicated in individuals with glaucoma, hyperthyroidism, or a history of recent stroke or cardiovascular events. It should not be used by patients with known hypersensitivity to either component. Due to the risk of metabolic acidosis, mood disturbances, and cognitive effects, caution is advised in patients with renal impairment, depression, or a history of suicidal thoughts. Regular monitoring of heart rate, mood changes, and serum bicarbonate levels is recommended during treatment. Avoid abrupt discontinuation due to the risk of seizures associated with topiramate withdrawal.

Phentermine HCl / Topiramate may interact with CNS depressants, diuretics, oral contraceptives, and carbonic anhydrase inhibitors. Concurrent use with MAO inhibitors can lead to hypertensive crisis and is strictly contraindicated. Topiramate may reduce the efficacy of estrogen-containing contraceptives, potentially leading to unintended pregnancy. Alcohol use may intensify central nervous system side effects such as dizziness or cognitive impairment. Patients should inform their healthcare provider about all medications and supplements before starting this therapy.

Common side effects include dry mouth, constipation, tingling sensations (paresthesia), insomnia, dizziness, and altered taste. Cognitive effects such as difficulty concentrating, memory issues, or confusion may also occur, particularly at higher doses. Serious adverse reactions can include mood changes, suicidal thoughts, increased heart rate, kidney stones, and metabolic acidosis. Vision disturbances such as acute myopia or secondary angle-closure glaucoma have also been reported. Side effects may be dose-dependent and often improve with continued use or dose adjustments.

This medication is strictly contraindicated during pregnancy due to the risk of birth defects, particularly orofacial clefts such as cleft lip or palate. Women of reproductive age must use effective contraception and undergo regular pregnancy testing during treatment. If pregnancy occurs, the medication should be discontinued immediately. The presence of either drug in breast milk is not well studied; however, due to potential adverse effects on the infant, use during breastfeeding is not recommended. A healthcare provider should evaluate risks and benefits before initiating therapy in women of childbearing potential.

Store this medication at 68°F to 77°F (20°C to 25°C) and away from heat, moisture and light. Keep all medicine out of the reach of children. Throw away any unused medicine after the beyond-use date. Do not flush unused medications or pour down a sink or drain.

1. Suprenza (phentermine hydrochloride) package insert. Cranford, NJ: Akrimax Pharmaceuticals; 2011 Oct.
2. Topamax (topiramate) package insert. Titusville, NJ: Janssen Pharmaceuticals, Inc.; 2021 Jun.
3. Trokendi XR (topiramate extended-release capsules) package insert. Rockville, MD: Supernus Pharmaceuticals; 2020 Nov.
4. Qudexy XR (topiramate) package insert. Maple Grove, MN: Upsher-Smith Laboratories; 2021 Feb.
5. Silberstein SD, Holland S, Freitag F, et al. Evidence based guideline update: pharmacologic treatment for episodic migraine prevention in adults. Report of the quality standards subcommittee of the American Academy of Neurology and the American Headache Society. Neurology 2012;78:1337-1345.
6. American Headache Society. The American Headache Society position statement on integrating new migraine treatments into clinical practice. Headache 2018;59:1-18.
7. Oskoui M, Pringsheim T, Billinghurst L, et al. Practice guideline update summary: Pharmacologic treatment for pediatric migraine prevention: Report of the Guideline Development, Dissemination, and Implementation Subcommittee of the American Academy of Neurology and the American Headache Society. Neurology 2019 [Epub ahead of print]
8. McElroy SL. Pharmacologic treatments for binge-eating disorder. J Clin Psychiatry 2017;78:14-19.
9. Work Group on Alcohol Use Disorder, American Psychiatric Association. Practice guideline for the pharmacological treatment of patients with alcohol use disorder. American Psychiatric Association 2018. Available on the web at https://psychiatryonline.org/doi/pdf/10.1176/appi.books.9781615371969.– LinkOpens in New Tab
10. Pringsheim T, Okun MS, Muller-Vahl K, et al. Practice guideline recommendations summary: Treatment of tics in people with Tourette syndrome and chronic tic disorders. Neurology 2019;92:896-906.
11. Adipex-P (phentermine hydrochloride tablets and capsules) package insert. Sellersville, PA: Teva Pharmaceuticals; 2013 Jan.
12. Zolkowska D, Rothman RB, Baumann MH. Amphetamine analogs increase plasma serotonin: implications for cardiac and pulmonary disease. J Pharmacol Exp Ther. 2006;318:604-610.
13. Filippi L, Fiorini P, Daniotti M. Safety and efficacy of topiramate in neonates with hypoxic ischemic encephalopathy treated with hypothermia (NeoNATI). BMC Pediatrics 2012;12:144-155.
14. Rosenfeld WE, Doose DR, Walker SA. A study of topiramte pharmacokinetics and tolerability in children with epilepsy. Pediatr Neurol 1999;20:339-344.
15. Manitpisitkul P, Shalayda K, Todd M. Pharmacokinetics and safety of adjunctive topiramate in infants (1-24 months) with refractory partial-onset seizures: a randomized, multicenter, open-label phase 1 study. Epilepsia 2013;54:156-164.
16. Mikaeloff Y, Rey E, Soufflet C. Topiramate pharmacokinetics in children with epilepsy aged from 6 months to 4 years. Epilepsia 2004;45:1448-1452.
17. Castano G, Mas R, Nodarse M, et al. One-year study of the efficacy and safety of policosanol (5 mg twice daily) in the treatment of type II hypercholesterolemia. Curr Ther Res 1995;56:296-304.
18. Filippi L, la Marca G, Fiorini P. Topiramate concentrations in neonates treated with prolonged whole body hypothermia for hypoxic ischemic encephalopathy. Epilepsia 2009;50:2355-2361.
19. Adipex-P (phentermine hydrochloride tablets and capsules) package insert. Sellersville, PA: Teva Pharmaceuticals; 2013 Jan.
20. Suprenza (phentermine hydrochloride) package insert. Cranford, NJ: Akrimax Pharmaceuticals; 2011 Oct.
21. Phentermine hydrochloride package insert. Newtown, PA: KVK-Tech Inc; 2010 April.
22. Steiner E, Villen T, Hallberg M, et al. Amphetamine secretion in breast milk. Eur J Clin Pharmacol 1984;27:123-4.
23. Kelly TE, Hackett PH. Acetazolamide and sulfonamide allergy: a not so simple story. High Alt Med Biol 2010;11:319-323.
24. Brackett CC. Sulfonamide allergy and cross-reactivity. Curr Allergy Asthma Rep 2007;7:41-48.
25. Platt D, Griggs RC. Use of acetazolamide in sulfonamide-allergic patients with neurologic channelopathies. Arch Neurol 2012;69:527-529.
26. Strom BL, Schinnar R, Apter AJ, et al. Absence of cross-reactivity between sulfonamide antibiotics and sulfonamide nonantibiotics. New Engl J Med 2003;349:1628-35.
27. Ben-Zeev B, Watemberg N, Augarten A, et al. Oligohydrosis and hyperthermia: a pilot study of a novel topiramate adverse effect. J Child Neurol 2003;18:254-7.
28. Yamamoto Y, Takahashi Y, Imai K. Risk factors for hyperammonemia in pediatric patients with epilepsy. Epilepsia 2013;54:983-989.
29. The American Geriatrics Society 2019 Beers Criteria Update Expert Panel. American Geriatrics Society 2019 updated AGS Beers Criteria for potentially inappropriate medication use in older adults. J Am Geriatr Soc 2019;00:1-21.
30. Health Care Financing Administration. Interpretive Guidelines for Long-term Care Facilities. Title 42 CFR 483.25(l) F329: Unnecessary Drugs. Revised 2015.
31. Food and Drug Administration MedWatch. Topamax (topiramate): label change – risk for development of cleft lip and/or cleft palate in newborns. Retrieved March 4, 2011. Available on the World Wide Web http://www.fda.gov/Safety/MedWatch/SafetyInformation/SafetyAlertsforHumanMedicalProducts/ucm245777.htm– LinkOpens in New Tab
32. Ohman I, Vitols S, Luef G, et al. Topiramate kinetics during delivery, lactation, and in the neonate: preliminary observations. Epilepsia 2002;43:1157-60.
33. Meridia® (sibutramine) package insert. North Chicago, IL: Abbott Laboratories; 2003 Oct.
34. Fastin® (phentermine) package insert. Philadelphia, PA: Beecham Laboratories; 1987 Oct.
35. Dexedrine® (dextroamphetamine) package insert. Research Triangle Park, NC; GlaxoSmithKline; 2007 Mar.
36. Kulig K, Moore LL, Kirk M, et al. Bromocriptine-associated headache: possible life-threatening sympathomimetic interaction. Obstet Gynecol. 1991;78:941—3.
37. Cesamet™ (nabilone) package insert. Costa Mesa, CA: Valeant Pharmaceuticals International; 2006 May.
38. Foltin RW, Fischman MW, Pedroso JJ, et al. Marijuana and cocaine interactions in humans: cardiovascular consequences. Pharmacol Biochem Behav 1987;28:459—94.
39. Azilect (rasagiline mesylate) tablets. Kansas City, MO: Teva Neurosciences, Inc.; 2014 May.
40. Elavil® (amitriptyline) package insert. Wilmington, DE: AstraZeneca Pharmaceuticals LP; 2000 Dec.
41. Chan JC, Cockram CS, Critchley JA. Drug-induced disorders of glucose metabolism. Mechanisms and management. Drug Saf 1996;15:135—57.
42. Halothane, USP package insert. North Chicago, IL: Abbott Laboratories; 1998 Mar.
43. Tenuate® (diethylpropion hydrochloride) package insert. Bridgewater, NJ: Aventis Pharmaceuticals; 2003 Nov.
44. Strattera® (atomoxetine) package insert. Indianapolis, IN: Eli Lilly and Company; 2008 May.
45. Serevent® Diskus (salmeterol xinafoate inhalation powder) package insert. Research Triangle Park, NC: GlaxoSmithKline; 2008 Mar.
46. Gadde KM, Allison DB, Ryan DH, et al. Effects of low-dose, controlled-release, phentermine plus topiramate combination on weight and associated comorbidities in overweight and obese adults (CONQUER): a randomised, placebo-controlled, phase 3 trial.
47. O’Neill PM, Peterson, CA. Weight Loss and Depression in Overweight/Obese Subjects With a History of Depression Receiving Phentermine and Topiramate Extended-Release. Presented at the 166th Annual Meeting of the American Psychiatric Association (APA
48. Bostwick JM, Brown TM. A toxic reaction from combining fluoxetine and phentermine. J Clin Psychopharmacol 1996;16:189—90.
49. Zolkowska D, Rothman RB, Baumann MH. Amphetamine analogs increase plasma serotonin: implications for cardiac and pulmonary disease. J Pharmacol Exp Ther. 2006;318:604-610.
50. Qsymia (phentermine and topiramate extended-release) package insert. Mountain View, CA: Vivus, Inc.; 2014 Sept.
51. Allison DB, et al. Controlled-release phentermine/topiramate in severely obese adults: a randomized controlled trial (EQUIP). Obesity (Silver Spring). 2012;20:330-342.
52. Brintellix (vortioxetine tablets) package insert. Deerfield, IL: Takeda Pharmacueticals America, Inc.; 2014 Jul.
53. Suprenza (phentermine hydrochloride) package insert. Cranford, NJ: Akrimax Pharmaceuticals; 2011 Oct.
54. Phentermine hydrochloride package insert. Newtown, PA: KVK-Tech Inc; 2010 April.
55. Lomaira (phentermine hydrochloride) package insert. Newton, PA: KVK-Tech, Inc.; 2016 Sept.
56. Hendricks EJ, Srisurapanont M, Schmidt SL, et al. Addiction potential of phentermine prescribed during long-term treatment of obesity. Int J Obes (Lond). 2014;38:292-298.
57. Depakote (divalproex sodium tablets) package insert. North Chicago, IL: AbbVie Inc.; 2020 May.
58. Page RL, Bainbridge JL. Intractable Epistaxis Associated with Topiramate Administration. Ann Pharmacother. 2006; Accessed online on July 5, 2006. Published Online, 5 July 2006. Available on the World Wide Web at: www.theannals.com, DOI 10.1345/aph.1H078
59. Kossoff EH, Pyzik PL, Furth SL. Kidney stones, carbonic anhydrase inhibitors, and the ketogenic diet. Epilepsia 2002;43:1168-1171.
60. Groeper K, McCann ME. Topiramate and metabolic acidosis: a case series and review of the literature. Paediatr Anaesth 2005;15:167-70.
61. Wilner A, Raymond K, Pollard R. Topiramate and metabolic acidosis. Epilepsia 1999;40:792-5.