Interaction between Disulfiram and Metronidazole (topical)
Moderate Synergy

ID DDInter576 and DDInter1203
Interaction Use of a nitroimidazole in patients treated with disulfiram may result in psychotic reactions. The exact mechanism of interaction is unknown, but may involve additive effects on aldehyde dehydrogenase (ALDH) inhibition. The interaction has been reported with metronidazole.
Management Nitroimidazole therapy should not be administered to patients who are taking disulfiram, or have taken it within the last two weeks.
References
Alternative for Disulfiram P03A
Lindane

N07B
Acamprosate
Buprenorphine
Levacetylmethadol
Diamorphine
Varenicline
Nicotine
Methadone
Lofexidine
Naltrexone
Nalmefene
Alternative for Metronidazole (topical) A02B
Tetracycline (topical)
Misoprostol
Pantoprazole
Famotidine
Esomeprazole
Amoxicillin
Levofloxacin
Sucralfate
Dexlansoprazole
Rabeprazole
Tetracycline
More

Potential Metabolism Interactions

Substrate-Substrate Interaction：If more than one drug is metabolized by the same CYP, it is possible that its metabolism is inhibited because of the competition between the drugs. That means, it can be useful to lower the dosage of the drugs in the drug-cocktail because they remain longer in the organism than in monotherapy.
Inhibitor-Inhibitor Interaction：Combining two or more inhibitors of one CYP, should be compensated by lowering the dosage of these drugs because the metabolism is reduced and the drugs remain longer in the organism than in monotherapy. Not adapting the dosage bears the risk of even more side effects.
Inhibitor-Substrate Interaction：Combining drugs that have inhibitory effect and are substrates of one particular CYP, should be compensated by lowering the dosage. They rest longer in the organism than in monotherapy. Not adapting the dosage bears the risk of even more side effects.