Benzethonium chloride was a synthetic, positively charged surfactant in the quaternary ammonium group. It was used in topical antimicrobial products and also served as a preservative or disinfectant in some formulations. Its CAS Registry Number was 121-54-0.
Rohm and Haas filed patents related to the compound between 1938 and 1941. Phemerol was recorded as a U.S. trade name from 1942, and Premithyn was introduced in 1959.
BRAND NAMES
Medical and pharmaceutical references listed Phemerol, Phemeride, Hyamine 1622, Premithyn, Benzalcan, Dalidyne, Desamon, Hyarom, Sterilette, and Uni Wash as names associated with benzethonium chloride.
MECHANISM OF ACTION
Benzethonium chloride’s proposed antimicrobial action involved its interaction with microbial cell surfaces and membranes. As a quaternary ammonium compound, it could disturb membrane structure and permeability, causing cell contents to leak and leading to microbial damage or death. The precise mechanism for benzethonium itself had not been fully established; this explanation was based on its chemical class and laboratory findings.
PHARMACODYNAMICS
Benzethonium chloride acted mainly as a local antimicrobial when applied in an appropriate topical formulation. Product labeling described its use in hand washing to reduce bacteria on the skin. Its effect depended on the product’s concentration, contact time, formulation, and the microorganisms present.
ADMINISTRATION
Benzethonium chloride was used in some antiseptic products applied to the skin. Directions depended on the product, so its own label was followed. It was for external use only and was not used in the eyes or swallowed. One 0.1% spray label directed users to apply it to the affected area up to three times daily.
DOSAGE AND STRENGTH
There was no single dose for all benzethonium products. U.S. labels listed strengths and directions that included:
0.1% spray: applied to the affected area up to three times daily.
0.2% cream: applied to the affected area and gently rubbed in.
0.2% liquid bandage: a small amount was applied 1–3 times daily and allowed to dry.
These products were not interchangeable. Some labels limited use to 7 or 10 days and advised seeking medical care if the condition persisted or worsened.
DRUG INTERACTIONS
The topical product labels reviewed did not list specific drug interactions. A pharmacist or clinician could advise whether it was appropriate to apply benzethonium to the same area as another topical medicine or antiseptic.
FOOD INTERACTIONS
The labels reviewed did not list food interactions for topical benzethonium products. If benzethonium was swallowed, urgent medical advice or contact with a local poison-control service was recommended.
CONTRAINDICATIONS
Benzethonium was used as a topical antiseptic in some products. People who had previously reacted allergically to benzethonium or another ingredient were advised not to use that product.
SIDE EFFECTS
Possible effects included skin redness, irritation, a burning sensation, or rash. Contact with the eyes could cause irritation or more serious injury, especially with concentrated products. People were advised to stop using the product and seek medical advice if irritation became severe, a rash appeared, or symptoms worsened.
OVER DOSE
If benzethonium was swallowed, urgent medical or poison-center advice was recommended, even if symptoms had not appeared. The mouth was to be rinsed, and vomiting was not to be induced. The product container or label was to be brought along. After eye exposure, the eyes were to be rinsed carefully with water; contaminated skin was to be washed thoroughly after removing affected clothing.
TOXICITY
The risk depended on the amount and concentration. Topical products were intended for external use, while swallowing benzethonium—particularly concentrated or laboratory-grade material—could cause severe poisoning. Possible effects included damage to the mouth, throat, or digestive tract, vomiting, breathing difficulty, collapse, and seizures.
