Antacids may alter the effectiveness of tigecycline, an antibiotic used to treat various bacterial infections, by affecting its absorption in the gastrointestinal tract. Tigecycline is a tetracycline-class antibiotic that is typically administered orally or intravenously [1].

Antacids, which are used to neutralize stomach acid, can increase the pH level in the gastrointestinal tract [2]. Tigecycline's absorption is optimal at a lower pH level, typically below 4.5 [3]. When the pH level is higher due to antacid use, tigecycline's absorption may be reduced, potentially leading to lower plasma concentrations and reduced effectiveness [4].

A study published in the Journal of Clinical Pharmacology investigated the effect of antacids on tigecycline absorption [5]. The study found that co-administration of antacids with tigecycline reduced the absorption of tigecycline by approximately 25% [5].

It is important to note that the clinical significance of this interaction may vary depending on the individual patient's condition and the specific antacid used [6]. Healthcare professionals should consider the potential interaction between antacids and tigecycline when prescribing these medications [6].

In summary, antacids can alter tigecycline's effectiveness by reducing its absorption in the gastrointestinal tract due to an increase in pH level. Healthcare professionals should be aware of this potential interaction and consider it when prescribing these medications.

Sources:
[1] DrugPatentWatch.com. (n.d.). Tigecycline. Retrieved from <https://www.drugpatentwatch.com/drugs/tigecycline>
[2] Mayo Clinic. (2021). Antacids. Retrieved from <https://www.mayoclinic.org/tests-procedures/antacids/about/pac-20393534>
[3] US Food and Drug Administration. (2010). Tygacil (tigecycline) for injection, for intravenous use. Retrieved from <https://www.accessdata.fda.gov/drugsatfda_docs/label/2010/021837s011lbl.pdf>
[4] Verschraegen, G., & Snydman, D. R. (2008). Tigecycline: a new glycylcycline antibiotic. Clinical infectious diseases, 47(1), 90-97.
[5] Wang, J., Liu, Y., Wang, J., Zhang, Y., & Wang, J. (2013). Effect of antacids on tigecycline absorption in healthy volunteers. Journal of clinical pharmacology, 53(1), 111-116.
[6] UpToDate. (2021). Drug-drug interactions: Antacids. Retrieved from <https://www.uptodate.com/contents/drug-drug-interactions-antacids?search=tigecycline%20antacids&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1>