Combination Dosage Forms Using Bupropion to Extend TBZ Exposure
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Solution Overview
Problem
The rapid hepatic metabolism of tetrabenazine (TBZ) and its metabolites, alpha-dihydrotetrabenazine (α-HTBZ) and beta-dihydrotetrabenazine (β-HTBZ), limits systemic drug exposure in extensive metabolizers, reducing their clinical utility due to low plasma levels.
Innovation Solution
Co-administration of antidepressants like bupropion with TBZ, α-HTBZ, or β-HTBZ to inhibit their metabolism, allowing for less frequent dosing and enhancing therapeutic efficacy by modulating pharmacological properties such as sigma-1 agonism and NMDA antagonism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If tetrabenazine is orally administered, then it is rapidly converted in the liver to active metabolites, but this rapid metabolism limits systemic drug exposure and reduces plasma levels in extensive metabolizers
Solution Approach 1:
The patent introduces bupropion as an intermediary substance that mediates between the rapid metabolism of TBZ and the need for sustained plasma levels. Bupropion inhibits CYP2D6, the enzyme responsible for metabolizing TBZ and its active metabolites, thereby acting as a protective intermediary that preserves drug exposure and extends half-life in extensive metabolizers
Solution Approach 2:
The patent changes the pharmacokinetic parameters of TBZ by co-administering bupropion. This combination alters the metabolic rate and half-life of TBZ metabolites, transforming the rapid clearance characteristic of extensive metabolizers into a more sustained drug exposure profile that maintains therapeutic plasma levels
2Quantity of substance
If antidepressants like bupropion are co-administered with TBZ to inhibit metabolism, then plasma levels and half-life are increased, but this may increase the risk of adverse effects
Solution Approach 1:
The patent employs feedback control through therapeutic drug monitoring and dose adjustment protocols. By monitoring plasma levels of TBZ and its metabolites while co-administering bupropion, clinicians can adjust doses to maintain therapeutic ranges and avoid toxic levels, creating a feedback loop that manages the risk of adverse effects while preserving the benefits of extended half-life
Solution Approach 2:
The patent applies partial action by using sub-maximal doses of bupropion that provide sufficient CYP2D6 inhibition to extend TBZ half-life without causing excessive noradrenergic stimulation. This partial inhibition strategy achieves the desired pharmacokinetic modification while minimizing the risk of adverse effects from over-inhibition
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances the therapeutic efficacy of TBZ by increasing plasma levels and extending its half-life, enabling less frequent dosing without loss of efficacy, and improving treatment outcomes for neurological disorders and pain.
Implementation Method 1
Bupropion, hydroxybupropion, erythrohydroxybupropion, threohydroxybupropion, or a metabolite or prodrug of any of these compounds, regardless of stereochemistry, can be effective in inhibiting or reducing the metabolism of tetrabenazine, alpha-dihydrotetrabenazine, or beta-dihydrotetrabenazine in some human beings.
Implementation Method 2
Deutetrabenazine is a 20 selectively deuterated form of TBZ in which the two O-linked methyl groups (CH3) of the TBZ molecule have been replaced by two trideuteromethyl groups (CD3). This deuteration is expected to increase the half-life of d6-α-HTBZ and d6-β-HTBZ and reduce the impact of CYP2D6 status
Data Source
AI summary
This disclosure relates to methods of administering bupropion, such as S-bupropion or R-bupropion, in conjunction with tetrabenazine, alpha-dihydrotetrabenazine, or beta-dihydrotetrabenazine to a human being. Dosage forms, drug delivery systems, and methods related to tetrabenazine, alpha-dihydrotetrabenazine, or beta-dihydrotetrabenazine and bupropion, such as S-bupropion or R-bupropion, are also disclosed.