Related Experiment Video
Updated: Jul 14, 2026
08:54
Validated LC-MS/MS Panel for Quantifying 11 Drug-Resistant TB Medications in Small Hair Samples
Published on: May 19, 2020
[Does generic lamotrigine lead to larger variations in plasma concentrations?]
Thomas Croft Buck1, Anne Schmedes, Ivan Brandslund
1Region Syddanmark, Damhaven 12, DK-7100 Vejle. thomas.buck@regionsyddanmark.dk.
Ugeskrift for Laeger
|June 8, 2007
Summary
Generic lamotrigine (an epilepsy drug) showed no significant changes in plasma concentrations compared to the original brand. This suggests comparable efficacy and safety between generic and original lamotrigine formulations.
Area of Science:
- Pharmacology
- Clinical Pharmacy
- Drug Efficacy
Background:
- Patent expiry of Lamictal (original lamotrigine) in June 2005 allowed for generic market entry.
- Investigated potential variations in lamotrigine plasma concentrations with generic formulations.
Purpose of the Study:
- To assess if generic lamotrigine use results in greater plasma concentration variability.
- To compare the therapeutic equivalence of generic versus original lamotrigine.
Main Methods:
- Patients in Vejle county using lamotrigine were categorized by brand usage (original, generic, or both).
- Defined Daily Doses (DDD) were calculated, and lamotrigine plasma levels were analyzed from clinical biochemistry databases.
Main Results:
- Median plasma lamotrigine concentrations showed no significant increase in variability post-patent expiry across groups.
- Patients switching to generic lamotrigine or using a mix of brands did not exhibit altered median plasma concentrations.
- Drug usage (DDD) remained comparable before and after patent expiry for all patient groups.
Conclusions:
- Generic lamotrigine does not induce significant changes or increased variability in plasma concentrations.
- No evidence suggests a difference in therapeutic effect between original and generic lamotrigine brands.
- Further studies on seizure frequency and side effects are recommended for comprehensive comparison.
Related Concept Videos
01:24Dosage Regimen: Individualization
Individualization in dosing regimens is the customization of medication doses for individual patients. Its necessity arises from the goal of maximizing therapeutic benefits while minimizing risks. This approach is pivotal because human responses to drugs can vary widely; what is effective for one person may be inadequate or excessive for another. Interpatient (intersubject) variability refers to differences in drug responses between individuals, while intrapatient (intrasubject) variability...
01:29Pharmacogenetic Phenotypes: Alterations in Pharmacokinetics, Drug Targets and Biologic Milieu
Genetic variations significantly influence drug response through pharmacokinetics, receptor interactions, and biologic milieu modifications. Pharmacokinetic alterations impact drug metabolism and clearance, affecting efficacy and toxicity. Variants in drug-metabolizing enzymes, such as CYP2C9 and CYP2C19, alter drug activation and elimination. For example, CYP2C9 loss-of-function variants require lower warfarin doses to prevent excessive bleeding, while CYP2C19 variants reduce clopidogrel...
01:09Bioequivalence of Drugs: Drugs with Multiple Indications
The concept of therapeutic equivalence (TE) in drugs with multiple indications is complex. A generic drug may be therapeutically equivalent to a brand-name product for one specific indication, but this doesn't necessarily mean it's equivalent for all other indications. Evidence of TE in one patient group and bioequivalence shown in healthy volunteers can support—but not confirm—TE for other indications. However, definitive proof requires individual clinical studies for each indication due to...
01:22Pharmaceutical Alternatives: Stability-Related Therapeutic Nonequivalence
Generic intravenous (IV) drugs are considered bioequivalent to their branded counterparts due to their 100% bioavailability upon administration. However, variations in stability among different drug products can significantly influence their therapeutic performance, even if they are pharmaceutically equivalent.Cefuroxime, a prophylactic antimicrobial, is often used as a single-dose IV injection for patients undergoing coronary artery bypass grafting surgery. A 3 g dose typically provides...
01:27Pharmaceutical Alternatives: Polymorphic Form-Related and Particle Size-Related Therapeutic Nonequivalence
Changes in polymorphic forms can significantly influence the bioavailability of poorly soluble drugs. Although the FDA defines pharmaceutical equivalence based on having the same active ingredient, dosage form, and route of administration, it does not automatically disqualify products with different polymorphic forms. This means two products with different polymorphs can still be deemed pharmaceutically equivalent. However, polymorphic differences can affect properties like wettability,...
01:20Antiepileptic Drugs: Modulators of Neurotransmitter Release Mediated by SV2A Protein
Antiepileptic drugs, such as levetiracetam (Keppra) and brivaracetam (Briviact), have emerged as crucial tools in managing epilepsy. These medications exert their therapeutic effects by targeting the synaptic vesicle protein SV2A, a transmembrane glycoprotein primarily found in the brain.
SV2A is a transmembrane glycoprotein located predominantly in the brain, modulating the release of neurotransmitters for neuronal communication. Both levetiracetam and brivaracetam exhibit a high affinity for...
SV2A is a transmembrane glycoprotein located predominantly in the brain, modulating the release of neurotransmitters for neuronal communication. Both levetiracetam and brivaracetam exhibit a high affinity for...