What's wrong with tramadol?
Lots.
1. It is an opiod but doesn't bind directly to opiod receptors/binds super weakly. Most of its opiod action is the result of a metabolite. So basically you are depending on the patient to have a good P450 system. A good portion of the population (up to 10%) don't have the right enzyme and then there are others who are ultrametabolizers. So basically, you are not prescribing a known amount of drug - just basically throwing at a dartboard blind.
2. Tramadol itself also acts as an SNRI. But none of its metabolites do. So between unknown opiod activity and the SNRI activity, you have an unknown mix of pharmacology.
3. Lots of side effect. Some of which likely connected to the SNRI effects. If you get the SNRI effect from the tramadol but it gets metabolized quickly, and you use tramadol persistantly, you get a cycle of withdrawal from the SNRI effects. People who use if for awhile get opiod withdrawal symptoms but it takes awhile because of the opiod metabolites that stick around - but they also get anxiety, panic attacks, hallucinations, etc associate with SNRI withdrawal, and that happens before the opiod withdrawal symptoms.
4. People mistakenly think it is good to prescribe a "weak" opiod because it has less addiction potential. But instead, what studies have found is that people take more tramadol to get analgesic effect. If you look at the studies, for a lot of people the actual analgeisa is equal to tylenol but worse than NSAIDs. So why bother? Just given them an actual opiod that you know will have X effect.
5. BMJ published a study that showed an association between postop op tramadol use for pain control and then persistent opiod use after the postop period - higher than other short acting opiods.
6. HUGE recreational use of tramadol worldwide - significantly euphoria association, studies have said consistent with heroin.
Summary: I don't let my residents prescribe it for my patients. You don't really know what the patient will be getting because it all depends on their P450 metabolism. It doesn't work well in general, and doesn't work at all for at least 10% of the population, but still has significant side effects.