What is the difference between the base and salt forms in Chloroquine (hydroxychloroquine) dosage formulations?

From the Guidelines

The primary difference between the base and salt forms of Chloroquine (hydroxychloroquine) dosage formulations lies in their molecular weight and active drug content, with the salt form containing less active medication by weight due to the additional molecules attached to the base. This distinction is critical in prescribing and taking chloroquine, as dosing must be adjusted accordingly to ensure efficacy and safety, particularly in antimalarial therapy 1.

Key Differences

• Chloroquine base refers to the pure active ingredient.
• Chloroquine salt includes additional molecules attached to the base, resulting in less active medication by weight.
• The salt form is generally more stable and better absorbed in the gastrointestinal tract, making it commonly used in oral formulations.

Clinical Implications

• Medication labels and prescriptions should clearly specify whether the dose is expressed as the base or salt form to prevent dosing errors.
• The difference in active drug content between the base and salt forms necessitates careful consideration in treatment regimens, especially for conditions like malaria where precise dosing is crucial.

Formulations and Usage

• Chloroquine phosphate, a salt form, is often used in oral formulations, with 250 mg of chloroquine phosphate containing approximately 150 mg of chloroquine base.
• Injectable forms may use different salt preparations, highlighting the need for clarity on the formulation being used.

In summary, understanding the difference between the base and salt forms of chloroquine is essential for accurate dosing and effective treatment outcomes, particularly in the context of malaria treatment as discussed in the provided evidence 1.

From the FDA Drug Label

The dosage of chloroquine phosphate is often expressed in terms of equivalent chloroquine base. Each 250 mg tablet of chloroquine phosphate tablet contains the equivalent of 150 mg chloroquine base. Each tablet contains 200 mg of hydroxychloroquine sulfate, USP equivalent to 155 mg base.

The difference between the base and salt forms in Chloroquine (hydroxychloroquine) dosage formulations is that the salt form (e.g. chloroquine phosphate or hydroxychloroquine sulfate) contains additional components such as phosphate or sulfate, whereas the base form refers to the active ingredient (chloroquine or hydroxychloroquine) only. The dosage is often expressed in terms of the equivalent base to standardize the amount of active ingredient. For example, 250 mg of chloroquine phosphate is equivalent to 150 mg of chloroquine base, and 200 mg of hydroxychloroquine sulfate is equivalent to 155 mg of hydroxychloroquine base 2, 3.

• Key points:
  • Salt form contains additional components
  • Base form refers to the active ingredient only
  • Dosage is often expressed in terms of equivalent base
  • Different formulations have different equivalent base amounts (e.g. 250 mg chloroquine phosphate = 150 mg chloroquine base, 200 mg hydroxychloroquine sulfate = 155 mg hydroxychloroquine base)

From the Research

Difference between Base and Salt Forms in Chloroquine (Hydroxychloroquine) Dosage Formulations

• The base form of a drug refers to the active pharmaceutical ingredient itself, without any additional components 4.
• The salt form, on the other hand, is a combination of the base and an acid, which can affect the drug's solubility, stability, and bioavailability 4.
• In the case of chloroquine, the base form is often referred to as "chloroquine base" 4.
• The salt form of chloroquine is typically administered as a phosphate or sulfate salt 4.
• The dosage of chloroquine is often expressed in terms of the base form, with a total cumulative dose of 25 mg of chloroquine base per kilogram of body weight 4.

Implications for Dosage and Administration

• The difference between the base and salt forms can have implications for dosage and administration 4.
• For example, the salt form may be more soluble and bioavailable than the base form, which can affect the drug's efficacy and toxicity 4.
• However, the specific differences between the base and salt forms of chloroquine are not explicitly stated in the provided studies [(5,4,6,7,8)].

Toxicity and Safety Considerations

• The toxicity and safety of chloroquine and hydroxychloroquine have been extensively studied 7.
• The studies suggest that the drugs can cause a range of adverse effects, including gastrointestinal, dermatologic, and neuropsychiatric effects 7.
• However, the differences between the base and salt forms in terms of toxicity and safety are not explicitly stated in the provided studies [(5,4,6,7,8)].