Antibiotics are a class of antimicrobial drugs used for treating bacterial infections. Drug interactions with alcohol are a niche area of research, many drugs react with alcohol and exhibit either Pharmacokinetic (interference in drug metabolism) or Pharmacodynamic (additive or antagonistic) interactions and antibiotics are no exception. Although very few findings of alcohol and antibiotic interactions (either direct or indirect) have been reported and studied thus far, it is assumed that alcohol can aggravate the side effects caused by certain if not all antibiotics. The focus of research on such interactions is currently on those having chronic drinking problems rather than those who occasionally drink and are on medication. It is but obvious that alcoholics are prone to infections and other complications due to adverse effects of alcohol and quite possibly an alcoholic person might be on some medication for a certain medical condition, due to which it becomes necessary to study whether these medications (antibiotics included) are predisposed to interaction with alcohol, in order to avoid complications.
One of the most commonly reported incidences with respect to alcohol antibiotic interactions is the “Disulfiram like reaction” generally associated with antibiotics such as Metronidazole, Isoniazid, and trimethoprim. Symptoms include headache, labored breathing, tachycardia or rapid heartbeat, nausea, abdominal pain, and dilated blood vessels resulting in flushed skin. Symptoms last for several minutes to several hours depending upon the severity of the reaction. Under normal conditions, alcohol metabolism in the liver starts with its conversion to acetaldehyde by the action of Alcohol Dehydrogenase enzyme followed by conversion to acetic acid (to be excreted) by the action of acetaldehyde dehydrogenase enzyme. Antibiotics like Metronidazole block the Alcohol Dehydrogenase enzyme resulting in elevated acetaldehyde levels in the blood that is responsible for the aforementioned symptoms. This is a typical example of Pharmacokinetic interaction between alcohol and antibiotics.
Drugs are xenobiotic (foreign) substances for the body and are usually metabolized by the enzyme Cytochrome P450 2C9. Isoniazid is an antibiotic against Tuberculosis bacteria. At low concentrations (occasional alcohol intake along with antibiotic), alcohol competes with Isoniazid for interacting with P450 2C9 enzyme resulting in increased drug concentrations in blood resulting in drug toxicity. Whereas in heavy drinkers, high alcohol concentration inhibits Isoniazid metabolism by P450 2C9resulting in significantly low amount of the drug being metabolized and thereby rendering it ineffective against Tuberculosis. This type of interaction between alcohol and antibiotics exemplifies a Pharmacodynamic interaction. In either case, drug toxicity can affect the Central Nervous System causing sedation and confusion adding to the effects of alcohol consumption. This is more pronounced in aged individuals who could be on other CNS medications thereby posing a risk of accidental death while driving or other activities that demand alertness and concentration.
Some of the commonly used antibiotics that result in severe implications for interaction with alcohol are as follows:
- Didanosine (Antiviral drug for HIV/AIDS): Elevated risk of Pancreatitis
- Rifampin (Antibacterial drug for tuberculosis): Increased risk of Hepatotoxicity
- Linezolid (Antibacterial): Risk of Increased blood pressure
- Ethionamide (Antibacterial drug for tuberculosis): Impairment of Central Nervous System
- Tinidazole (Antiprotozoal and Antibacterial): Result in Disulfiram-like reactions