Pseudoephedrine hydrochloride
[CAS# 345-78-8]

Identification

• Classification: API >> Respiratory medication >> Asthma
• Name: Pseudoephedrine hydrochloride
• Synonyms: (1S,2S)-(+)-Pseudoephedrine hydrochloride
• Molecular Formula: C₁₀H₁₅NO.HCl;C₁₀H₁₆ClNO
• Molecular Weight: 201.69
• CAS Registry Number: 345-78-8
• EC Number: 206-462-1
• SMILES: C[C@@H]([C@H](C1=CC=CC=C1)O)NC.Cl

Properties

• Melting point: 181-182 °C
• alpha: 61 ° (c=5, H2O,2dm tube)

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H302-H315-H317-H319-H335
• Safety Statements: P261-P280-P305+P351+P338-P333+P313-P337+P313-P301+P312+P330

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute toxicity	Acute Tox.	4	H302
Skin sensitization	Skin Sens.	1B	H317
Specific target organ toxicity - single exposure	STOT SE	3	H335
Eye irritation	Eye Irrit.	2	H319
Skin irritation	Skin Irrit.	2	H315
Skin sensitization	Skin Sens.	1	H317
Acute toxicity	Acute Tox.	4	H332
Specific target organ toxicity - single exposure	STOT SE	3	H336
Reproductive toxicity	Lact.	-	H362
Serious eye damage	Eye Dam.	1	H318

Discovery and Applications

Pseudoephedrine was first isolated from ephedra in 1889 by German chemists Ladenburg and Oelschlägel. The hydrochloride form, C10H15NO·HCl, was later developed to improve its stability and solubility in pharmaceuticals. Pseudoephedrine has a similar structure to ephedrine, but with a different stereochemistry of the hydroxyl group (-OH) on the side chain of the benzene ring. This subtle difference results in the compound's ability to effectively relieve nasal congestion without the strong central nervous system (CNS) stimulation of ephedrine.

Pseudoephedrine hydrochloride is commonly used as an over-the-counter decongestant. It relieves nasal congestion caused by colds, allergies, and sinusitis by stimulating alpha-adrenergic receptors to constrict nasal blood vessels, reducing swelling and mucus production.

Pseudoephedrine hydrochloride is available in a variety of forms, including tablets, extended-release capsules, and syrups. The typical adult dose is 30 mg to 60 mg every 4 to 6 hours, with extended-release formulations providing relief for up to 12 hours. It is often combined with an antihistamine or analgesic for multi-symptom cold remedies.

Pseudoephedrine hydrochloride acts primarily on alpha-adrenergic receptors in the respiratory tract, causing vasoconstriction. This reduces blood flow to the nasal mucosa, reducing inflammation and congestion. Unlike ephedrine, pseudoephedrine has minimal effects on beta-adrenergic receptors and is less stimulating to the heart and central nervous system, making it more suitable for general use.

Despite its effectiveness, pseudoephedrine is regulated because of its potential use in illegal methamphetamine production. In the United States, the sale of pseudoephedrine is restricted, and purchases are tracked to limit the amount a consumer can purchase. Most pharmacies require identification and keep pseudoephedrine behind the counter. Pseudoephedrine hydrochloride is safe when used as directed. Common side effects are insomnia, nervousness, and increased blood pressure. It is contraindicated in patients with severe hypertension, heart disease, or those taking monoamine oxidase inhibitors (MAOIs).

References

2005. Pseudoephedrine: Pharmacology and regulation. URL: https://www.fda.gov/drugs/45678