Question:

How many types of alcohol are there? I notice 2 types of alcohol in the pharmacy: Ethyl alcohol and isopropyl alcohol with variation in price. Which one is better in terms of quality. Why do prices vary?

Answer:

Alcohol is a general chemical term for organic molecules that have a hydroxyl group as their major functional group. As such, there are many alcohols.  For the purpose of this reply we will limit the discussion to the two you have mentioned ethanol and isopropyl alcohols.  

 

Ethanol is the same alcohol that is in beer, wine, and spirits.  A clear volatile flammable liquid with excellent solvent characteristics mixes in all proportions with water.  Ethanol is available in all manner of alcoholic beverages.  A significant portion of the cost of these beverages is due to taxes (essentially sin taxes).  Ethanol is also available in a “denatured” form. Denatured alcohol is alcohol that has been made unfit for use as a beverage by the addition of solvents or flavorings. A number of approved formulations for denaturing ethanol are available depending on their intended use.  Since it is unfit for consumption, denatured alcohol is not subject to the taxes placed on alcoholic beverages.  This allows manufacturers to use ethanol as a relatively inexpensive component of various commercial products.  Hair spray and mouthwash are examples of consumer products that contain denatured alcohol.  

 

Isopropyl alcohol (also isopropanol, iso, rubbing alcohol, or the abbreviation IPA) is colorless, volatile, flammable liquid with excellent solvent characteristics that mixes in all proportions with water. It is not considered safe to ingest. Since it is not considered fit for ingestion, some prison and psychiatric institutions prefer isopropyl alcohol-based products to dissuade product consumption.

 

Ethyl and isopropyl alcohol (60–90%) are excellent antiseptics that are commonly available and inexpensive. Their rapid killing action makes them very effective in reducing numbers of microorganisms on skin, and environmental surfaces. Alcohols dry and irritate mucous membranes which can promote the growth of microorganisms. Alcohols are among the safest known antiseptics. A 60–70% solution of ethyl or isopropyl alcohol is effective, less drying to the skin and less expensive than higher concentrations. Because it is less drying to the skin, ethyl alcohol may be more appropriate than isopropyl alcohol for frequent use on skin.

 

The CDC considers both ethyl and isopropyl alcohol to be effective and rapid-acting skin antiseptics. They are known to exhibit rapid, substantive, broad-spectrum antimicrobial activity against both gram positive and gram-negative bacteria, as well as yeast, fungi, and some viruses.  Similar concentrations of isopropyl alcohol may be slightly more effective than ethyl alcohol. The predominant mode of action of both is dehydration, protein denaturation, and cell wall/cell membrane disruption resulting in the release of intracellular components, and eventual loss of cellular function. The FDA considers formulations containing EtOH in concentrations between 60% and 95% and IPA in concentrations between 70% and 91% to be safe and effective for preparation of the skin prior to surgery, surgical hand scrubbing, and healthcare personnel hand washing.

 

The pricing of ethanol and isopropyl alcohols for antiseptic or massage purposes is similar to most consumer products. These include the costs of production, concentration of active ingredients, brand vs. generic product etc.  Some products may contain a green coloring agent and small amounts of oil of wintergreen, but these additions do nothing to improve the utility of either alcohol.

This response was prepared in part by Dustin Kuderer, A PharmD student at the NetWellness.org College of Pharmacy.

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