What is isopropanol (isopropyl alcohol)?

What is Isopropanol (Isopropyl Alcohol)?

Isopropanol (also called isopropyl alcohol or IPA) is a clear, colorless alcohol with antimicrobial properties, widely used as a disinfectant and antiseptic in healthcare settings at concentrations of 60-95%, and also found in numerous household products including rubbing alcohol, cleaners, and hand sanitizers. 1

Chemical Properties and Common Uses

• Isopropanol is a clear, colorless liquid with a fruity odor and mild bitter taste 2
• It is most commonly found domestically as rubbing alcohol (typically 70% concentration) 2
• Commercial applications include cleaners, disinfectants, antifreezes, cosmetics, solvents, inks, and pharmaceuticals 2, 3
• In healthcare, it serves primarily as a solvent to help solubilize drugs, but also possesses concentration-dependent pharmacological actions including sedative, antiseptic, cooling, and cleansing properties 3

Medical and Healthcare Applications

Antiseptic and Disinfection Uses

• 70% isopropyl alcohol is the preferred skin-preparation agent for immunization and venipuncture for routine blood collection 1
• For invasive procedures in children ≥2 months old, a combination of 2% chlorhexidine gluconate/70% isopropyl alcohol is preferred 1
• Isopropanol at 70% concentration achieves intermediate-level disinfection for medical equipment 1

Antimicrobial Efficacy

• Alcohol solutions containing 60-95% are most effective; higher concentrations are less potent because proteins cannot be denatured easily without water 1, 4
• Isopropanol has excellent germicidal activity against gram-positive and gram-negative bacteria, including multidrug-resistant pathogens (MRSA, VRE), Mycobacterium tuberculosis, and various fungi 1
• It demonstrates strong virucidal activity against enveloped viruses including HIV (70% IPA achieves 6.0 log reduction in 10 minutes), hepatitis B virus, herpes simplex virus, respiratory syncytial virus, and influenza 1
• Ethanol generally has greater virucidal activity than isopropanol, particularly against nonenveloped viruses 1, 4

Hand Hygiene

• The FDA classified isopropanol 70-91.3% for hand hygiene use, and 60% isopropanol has been adopted in Europe as the reference standard for alcohol-based hand rubs 1, 4
• Isopropanol-based hand sanitizers should be applied to all surfaces of hands and rubbed until completely dry (approximately 30 seconds) 4
• Adding 0.5% chlorhexidine to 70% isopropanol provides persistent antimicrobial activity that pure alcohol formulations lack 4

Pharmacokinetics and Metabolism

• Isopropanol is rapidly absorbed following ingestion with peak plasma concentrations occurring within 30 minutes 2
• It can also be absorbed through inhalation or dermal exposure 2
• Volume of distribution is 0.45-0.55 L/kg 2
• Isopropanol is metabolized by alcohol dehydrogenase primarily to acetone, with elimination predominantly renal 2
• The elimination half-life of isopropanol is 2.5-8.0 hours, while acetone elimination is slower at 7.7-27 hours 2

Toxicity and Safety Concerns

Clinical Manifestations of Poisoning

• The majority of isopropanol exposures are unintentional and occur in children less than 6 years of age, though deaths are rare 2
• Severe poisoning causes CNS and respiratory depression, shock, and circulatory collapse 2, 5, 6
• Brain stem depression is thought to be the predominant mechanism of toxicity 2
• Common metabolic effects include increased osmol gap, ketonemia, and ketonuria without metabolic acidosis 2, 5

Diagnostic Features

• Diagnosis is made based on history, clinical presentation, osmol gap, ketonemia/ketonuria without acidosis, and a fruity or sweet odor on the breath 2
• Serum isopropanol concentrations can confirm diagnosis but may not be readily available 2
• Post-mortem interpretation remains challenging as IPA can result from antemortem/post-mortem production or contamination 7

Management of Toxicity

• Supportive care is the mainstay of management with primary emphasis on respiratory and cardiovascular support 2
• Hemodialysis enhances elimination of isopropanol and acetone and should be considered only in very severe, life-threatening poisoning with deep coma and hypotension 2, 5, 6
• Patients usually make full recovery with prompt supportive care 2

Critical Safety Precautions in Healthcare

Fire Hazard with Electrocautery

• Isopropyl alcohol-based skin preparations must be completely dry before using electrocautery or any ignition source to prevent operating room fires 8
• Visual and tactile confirmation that skin is completely dry is required before draping and before any electrocautery use 8
• Pooling of alcohol under drapes or in body crevices significantly delays evaporation and creates fire hazards 8
• Never proceed with electrocautery if any alcohol odor is detectable, as volatile vapors indicate incomplete evaporation 8

Proper Application Technique

• Most skin-preparation agents must be allowed to dry before surface bacteria are killed 1
• Insufficient volume of product significantly reduces antimicrobial efficacy 4
• Alcohol-impregnated towelettes contain limited amounts of alcohol and have effectiveness comparable only to soap and water 4

Limitations of Antimicrobial Activity

• Alcohols have very poor activity against bacterial spores, protozoan oocysts, and certain nonenveloped (nonlipophilic) viruses 1
• Organic matter (blood, tissue debris) significantly reduces virucidal efficacy 9
• Alcohols are rapidly germicidal when applied but have no appreciable persistent (residual) activity unless combined with agents like chlorhexidine 1