Anti-Acid Meds Lower Strength of Systemic Sclerosis Drug

Randy Dotinga

October 10, 2023


Anti-acid drugs used by patients with systemic sclerosis reduce the bioavailability of mycophenolate mofetil (MMF).


  • Researchers conducted an open-label, pragmatic crossover study of 20 patients (all female) with systemic sclerosis at a single center who were on a stable MMF dose (1.5-2 g/day) for the last 3 months or more.

  • Participants sequentially took MMF alone for 1 month, then with the H2 receptor blocker (HRB) ranitidine 300 mg/day in the second month, then with the proton pump inhibitor (PPI) esomeprazole 40 mg/day in the third month.

  • Researchers measured the bioavailability of MMF in the patients during treatment with ranitidine or esomeprazole and the impact of the drugs on the total GI score of the UCLA Scleroderma Clinical Trial Consortium Gastrointestinal Tract 2.0 instrument.

  • Patients were excluded if they were receiving co-prescription of cholestyramine, magnesium- or aluminum-containing antacids, and rifampicin; taking prednisolone-equivalent dose > 5 mg/day; taking MMF plus a PPI or an HRB at baseline; living with chronic kidney disease with a glomerular filtration rate < 30 mL/min; positive for HIV, HCV, or HBV; or living with end-stage lung disease or gastroduodenal ulcers.


  • Mean estimated 12-hour area under curve levels of mycophenolic acid dropped by 32.7% (mean difference = 22.28 μg h mL–1) when patients added esomeprazole, and they dipped by 21.97% (mean difference = 14.93 μg h mL–1) when they added ranitidine vs MMF alone.

  • The pharmacokinetic parameter T-max did not differ significantly between MMF alone vs MMF plus ranitidine but was significantly different with esomeprazole. C-max significantly declined with administration of ranitidine or esomeprazole vs MMF alone.

  • Total GI scores dipped when patients added esomeprazole or ranitidine.


In patients with significant gastroesophageal reflux disease symptoms who need to take MMF, management options may include monitoring MMF drug levels, switching to enteric-coated mycophenolate sodium, and spacing doses with anti-acid drugs.


Glaxon Alex, MD, and colleagues from the Center for Arthritis and Rheumatism Excellence in Kochi, India, conducted the study, which was published online September 28 in Seminars in Arthritis & Rheumatism.


The sample size is small, and the optimum dose of MMF is unknown.


The study had no outside funding. The authors report no relevant financial relationships.  

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