First-Generation Obesity Drugs: Why Older Medications Still Matter

First-generation obesity medications — phentermine, orlistat, phentermine/topiramate ER, bupropion/naltrexone SR, and liraglutide 3.0 mg — remain effective and clinically relevant despite the arrival of newer incretin-based therapies. While their average weight loss is lower than next-generation drugs, clinical trial data show that a substantial proportion of patients on these agents achieve 10% or more total body weight loss. The review emphasizes these medications as cost-effective, evidence-based tools for managing obesity-related atherosclerosis and other cardiometabolic complications.

Narrative review of pharmacologic profiles, clinical trial evidence, and practical considerations for five first-generation obesity medications.

With newer GLP-1 drugs dominating headlines, older obesity medications risk being overlooked — even though they remain affordable, accessible, and effective for many patients. This review reminds clinicians that first-generation agents, including the peptide-based liraglutide, still have a critical role in comprehensive obesity care, especially where cost or access to newer drugs is a barrier.

The obesity treatment landscape has expanded rapidly with drugs like semaglutide and tirzepatide, but access remains limited by cost and insurance coverage. First-generation agents — especially liraglutide, the only peptide in this group — fill critical gaps in care and may be used alone or in combination with newer therapies.

As a narrative review, this paper does not present new clinical data or perform a systematic analysis. Findings are limited to summarizing existing trial evidence without meta-analytic pooling.