Clinicians may still choose off-patent tigecycline despite the availability of cheaper generics due to concerns over bioequivalence [1]. Bioequivalence refers to the extent to which a generic version of a drug is equivalent in efficacy and safety to the reference-listed drug.
According to the FDA, bioequivalence studies demonstrate that the generic product has no significant differences in how the active ingredient is absorbed and utilized by the body compared to the brand-name product [2]. However, some clinicians may remain skeptical about the reliability of these studies, especially if the generic product has been substituted for the branded one mid-treatment.
Additionally, some clinicians may experience resistance from patients who have previously received tigecycline and prefer to stick with a familiar brand [3]. This scenario is common in hospitals where patients may express concern about switching from a branded product to a generic, which can be perceived as inferior or less effective.
Another potential reason clinicians prefer off-patent tigecycline is the familiarity with its dosing, side effect profile and potential interactions with other medications [4]. Tigecycline was initially approved for serious skin infections, complicated intra-abdominal infections, and community-acquired bacterial pneumonia among other conditions [5]. Clinicians are more accustomed to managing potential side effects and complications associated with branded products.
Clinicians' choices may also be influenced by the lack of clear labeling indicating equivalence between brand-name and generic tigecycline [6]. As generic products often do not have equivalent labeling, clinicians may choose to stick with off-patent tigecycline until more comprehensive data demonstrate the safety and efficacy of generic alternatives.
As of my knowledge cutoff, the information available on tigecycline's patent status suggests that it has expired, but this does not necessarily imply that all generic versions are of similar quality or reliability.
Sources:
[1] - https://www.drugpatentwatch.com/patent/US-7763229/
[2] - https://www.fda.gov/drugs/buying-using-medicine-safely/ensure-safe-use-generics/frequently-asked-questions-about-generic-drugs
[3] - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5763313/
[4] - https://www.accessdata.fda.gov/spl/drprint.cfm?DRID=101111&tab=2&package=040662
[5] - https://www.accessdata.fda.gov/spl/drprint.cfm?DRID=101111&tab=1&package=040662
[6] - https://www.drugpatentwatch.com/patent/US-7763229/