Quinidine Gluconate is the D-gluconate salt of quinidine, a naturally occurring cinchona alkaloid with established Class Ia antiarrhythmic activity and historical antimalarial activity. Quinidine acts primarily by blocking cardiac sodium channels and modifying cardiac conduction and repolarization.
Quinidine Gluconate has the molecular formula C₂₀H₂₄N₂O₂·C₆H₁₂O₇, corresponding to C₂₆H₃₆N₂O₉, and a molecular weight of 520.57 g/mol. The USP monograph identifies it as quinidine mono-D-gluconate salt.
Quinidine Gluconate is classified as a Class Ia antiarrhythmic agent. Quinidine also has antimalarial schizonticidal activity, although its principal modern pharmaceutical relevance is as an antiarrhythmic drug.
Quinidine produces antiarrhythmic activity primarily through blockade of fast sodium channels in cardiac tissue. This slows conduction and reduces the excitability of cardiac muscle.
It also affects potassium-channel-mediated repolarization, resulting in prolongation of the action potential and effective refractory period. These electrophysiological effects account for its Class Ia antiarrhythmic classification.
Quinidine can also inhibit CYP2D6, which is relevant to its drug-interaction profile.
Quinidine Gluconate API is used in pharmaceutical development and manufacture of quinidine-containing formulations for:
Current U.S. labeling identifies quinidine gluconate extended-release tablets as a quinidine product and provides a 324 mg quinidine gluconate tablet strength.
Quinidine Gluconate is described in the USP material as the gluconate salt of the quinidine alkaloid. A commercial USP specification describes the material as white or almost white or colourless, fine, silky needles, often in clusters.
Important numerical physicochemical characteristics include:
| Property | Value |
|---|---|
| Molecular Weight | 520.57 g/mol |
| Exact Mass | 520.24208073 Da |
| H-Bond Donors | 7 |
| H-Bond Acceptors | 11 |
| Rotatable Bonds | 9 |
| TPSA | 184 Ų |
| Heavy Atom Count | 37 |
PubChem reports these calculated molecular descriptors for Quinidine Gluconate.
Quinidine Gluconate API can be characterized using:
The USP monograph includes identification procedures involving fluorescence, TLC, optical rotation and a gluconate test.
The USP Quinidine Gluconate monograph provides a verified numerical assay requirement of:
NLT 99.0% and NMT 100.5% of total alkaloid salt, calculated as quinidine gluconate on the dried basis.
A publicly available USP-NF 2022 product specification also reports the following numerical quality parameters:
For a production API, the current applicable USP-NF edition or registered specification should take precedence over older commercial specification sheets.
Quinidine is a stereochemically defined cinchona alkaloid. The USP chemical name specifies the (9S) quinidine configuration, while the D-gluconate component is also stereochemically defined.
Therefore, stereochemical identity and optical rotation can be relevant quality attributes for Quinidine Gluconate API.
USP-related specifications recommend storing Quinidine Gluconate in well-closed, light-resistant containers. A commercial USP-NF 2022 specification states that the material should be stored in its original packaging to protect it from light.
For finished quinidine gluconate tablets, current DailyMed labeling specifies storage at 20–25°C (68–77°F) in a tight, light-resistant container.
For bulk API, storage should follow the validated stability data and applicable API specification.
Typical documentation for Quinidine Gluconate API may include:
Quinidine Gluconate API manufacturing involves controlled isolation or synthesis of the quinidine gluconate salt, purification, drying and analytical qualification.
Because the USP monograph establishes specific assay and impurity controls, manufacturing quality systems should focus particularly on total alkaloid content, cinchonine, quininoine, dihydroquinidine gluconate, other related alkaloids, moisture and inorganic residue.
| Parameter | Specification |
|---|---|
| Appearance | white to off-white crystalline powder |
| Identification | IR & HPLC compliant |
| Assay (HPLC) | 99.0–100.5% |
| Loss on Drying | NMT 2.0% |
| Residue on Ignition | NMT 0.15% |
| Individual Impurity | NMT 0.10% |
| Total Impurities | NMT 0.50% |