Chanced upon this older thread started in June2006  I am bumping it up; http://www.cpnhelp.org/flagylvstinidazole for reference and the original thread in context.

I am extracting a post that is very interesting to me and my situation.  Hope that some others may find it an interesting read as well.  Louise

Here is a good comparison review from Medscape on Tindamax and Flagyl. 

Several posters here have remarked that Tindamax is better tolerated than Flagyl - makes me wonder if Flagyl may hit people harder with porphyriaⁱi Vs Tindamax due to P450 metabolism. 

The data seems to be conflicting on how each drug is metabolized. 

This review from Medscape says "In an in vitro study, tinidazole was not observed to inhibit hepatic cytochrome P450 enzymes. " 

From Tindamax PI labeling,  "Tinidazole is biotransformed mainly by CYP3A4. In an in vitro metabolic drug interaction study, tinidazole concentrations of up to 75 [micro ]g/mL did not inhibit the enzyme activities of CYP1A2, CYP2B6, CYP2C9, CYP2D6, CYP2E1 and CYP3A4. "

From March 2007, The Annals of Pharmacotherapy on Flagyl - Link

Elevated plasma concentrations and toxicities have been reported for a number of CYP3A substrates including amiodarone, carbamazepine, quinidine, tacrolimus, and cyclosporine when administered with metronidazolei. This has led to the widespread belief that metronidazole is a significant inhibitor of CYP3A4. However, 4 pharmacokinetic studies conducted in humans showed that metronidazole did not increase plasma concentrations of the CYP3A substrates midazolam, erythromycin, cyclosporine, and alprazolam, thereby refuting the suggestion that metronidazole is a CYP3A4/5 inhibitor.  

Either way, we start Tindamax tomorrow.  Perhaps less porphyria???