What is the Difference Between Chlorpheniramine and Diphenhydramine?

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Chlorpheniramine and diphenhydramine are both antihistamine medications used to treat allergy symptoms, hay fever, and the common cold. They work by blocking histamine receptors in the body, preventing allergic reactions from occurring. However, there are some differences between the two drugs:

  1. Administration: Chlorpheniramine is typically administered orally as tablets, while diphenhydramine can be administered either orally or as an injection.
  2. Dosage: Chlorpheniramine has a lower dosage, whereas diphenhydramine has a comparatively higher dosage.
  3. Sedation: Chlorpheniramine tends to cause less drowsiness than diphenhydramine, making it a preferred choice for daytime use when drowsiness would be detrimental.
  4. First-generation vs. second-generation: Diphenhydramine is a first-generation antihistamine, while chlorpheniramine is a second-generation antihistamine. First-generation antihistamines tend to cause more sedation and other side effects due to their ability to cross the blood-brain barrier, while second-generation antihistamines are less likely to cause these side effects.

In summary, chlorpheniramine and diphenhydramine are both antihistamines used to treat allergy symptoms, but they differ in their administration, dosage, sedation effects, and classification as first- or second-generation antihistamines.

Comparative Table: Chlorpheniramine vs Diphenhydramine

Chlorpheniramine and Diphenhydramine are both antihistamine drugs used to treat allergy symptoms, hay fever, and the common cold. Here is a table comparing the differences between the two:

Property Chlorpheniramine Diphenhydramine
Chemical Formula C16H19ClN2 Unknown
Molar Mass 274.79 g/mol Unknown
Solubility in Water 0.55 g/100 mL Unknown
Bioavailability 25-50% Unknown
Protein Binding 72% Unknown
Elimination Half-Life 13-43 hours Unknown
Excretion Kidney Unknown
Sedating Properties Less sedating More sedating
FDA Approval Date July 13, 1949 March 4, 1946
drug Interactions Interacts with 337 drugs Interacts with 438 drugs

Chlorpheniramine is a type of antihistamine that works by blocking a certain natural substance the body makes during an allergic reaction, providing relief from symptoms such as rash, watery eyes, itchy eye/nose/throat/skin, cough, and runny nose. Diphenhydramine is also an antihistamine that works by blocking histamine, a substance produced during an allergic reaction, thereby reducing or eliminating associated symptoms. However, it readily crosses the blood-brain barrier, causing drowsiness as a side effect. Both medications have a long history of use and are backed by numerous clinical studies.