Which statement is true regarding the free base form of a drug, compared to the hydrochloride salt (HCI salt) form?
A. The free base form is usually the less potent form of the drug.
B. The free base form is generally more soluble in water than the HCI salt.
C. The free base form of the drug is less likely to exist in the solid phase.
D. The free base form of the drug has better stability than the HCI salt.
The correct answer and explanation is:
The correct answer is C. The free base form of the drug is less likely to exist in the solid phase.
Explanation:
Drugs are often formulated as either free bases or as salts (such as hydrochloride salts). The free base form refers to the drug in its uncharged molecular form, while the salt form, such as the hydrochloride (HCI) salt, involves the drug molecule being ionized and combined with an acid (like hydrochloric acid).
In general, the free base form is less stable in solid form because it lacks the ionic bonds that help stabilize the salt form. This instability makes it less likely to exist in the solid phase under normal conditions. The salt form, on the other hand, is typically more stable and easier to handle.
- A. The free base form is usually the less potent form of the drug – This is not necessarily true. The potency of the drug depends on how well it binds to its target, and this can vary depending on the drug’s chemical properties in different forms. While the salt form may have better solubility, the potency is not always reduced in the free base form.
- B. The free base form is generally more soluble in water than the HCI salt – This statement is false. Generally, the salt form of the drug is more soluble in water than the free base because salts are more hydrophilic (water-soluble) due to the ionic bonds, whereas the free base may be hydrophobic (less soluble).
- D. The free base form of the drug has better stability than the HCI salt – This is incorrect. The salt form is usually more stable because the ionic interactions stabilize the compound, making it less prone to degradation than the free base form.
In summary, the free base form is less likely to remain stable in the solid phase compared to the salt form, which is more commonly used for its enhanced stability and solubility.