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Achlorhydria Medication

  • Author: Divyanshoo Rai Kohli, MD; Chief Editor: BS Anand, MD  more...
Updated: Jul 15, 2016

Medication Summary

Achlorhydria may be associated with vitamin B-12 deficiency in the setting of pernicious anemia. Parenteral vitamin B-12 may be important in selected patients.

Achlorhydria is associated with thiamine deficiency in the setting of bacterial overgrowth. Bacterial overgrowth is commonly treated with the following antimicrobials: metronidazole, amoxicillin-clavulanate potassium, ciprofloxacin, or rifaximin.

H pylori infection can be treated with 3 drugs: PPI, clarithromycin, and amoxicillin. Levofloxacin can be used in place of amoxicillin for patients who are allergic to penicillin.



Class Summary

Vitamin B-12 (cobalamin) deficiency initially and typically manifests as macrocytic anemia, although neurologic symptoms may be present.

Cyanocobalamin (Crystamine, Cyomin, Crysti 1000)


Deoxyadenosylcobalamin and hydroxocobalamin are the active forms of vitamin B-12 in humans. Vitamin B-12 is synthesized by microbes but not by humans or plants. Vitamin B-12 deficiency may result from intrinsic factor deficiency (pernicious anemia), partial or total gastrectomy, or diseases of the distal ileum.



Used for thiamine deficiency syndromes.



Class Summary

Empiric antimicrobial therapy must be comprehensive and should cover all likely pathogens in the context of the clinical setting.

Metronidazole (Flagyl)


Component of drug combination therapy that effectively treats duodenal ulcer or gastric ulcer associated with H pylori infection. Active against various anaerobic bacteria and protozoa. Appears to be absorbed into cells. Intermediate-metabolized compounds are formed which bind DNA and inhibit protein synthesis, causing cell death.

Antibiotics and other agents are used as adjuvants to treat duodenal ulcer disease associated with H pylori.

Clarithromycin (Biaxin)


Semisynthetic macrolide antibiotic that reversibly binds to P site of 50S ribosomal subunit of susceptible organisms and may inhibit RNA-dependent protein synthesis by stimulating dissociation of peptidyl t-RNA from ribosomes, causing bacterial growth inhibition.

If H pylori is identified as the underlying cause of gastritis, subsequent eradication now is almost generally accepted practice. Protocols for H pylori eradication require a combination of antimicrobial agents and antisecretory agents, such as PPIs, ranitidine bismuth citrate (RBC), or bismuth subsalicylate. Despite the combinatorial effect of drugs in regimens used to treat H pylori infection, cure rates remain, at best, 80-95%.

Levofloxacin (Levaquin)


S (-) enantiomer of ofloxacin. Inhibits DNA gyrase in susceptible organisms thereby inhibits relaxation of supercoiled DNA and promotes breakage of DNA strands.

Ciprofloxacin (Cipro, Cipro XR)


Fluoroquinolone that inhibits bacterial DNA synthesis and, consequently, growth, by inhibiting DNA gyrase and topoisomerases, which are required for replication, transcription, and translation of genetic material. Quinolones have broad activity against gram-positive and gram-negative aerobic organisms. Has no activity against anaerobes. Continue treatment for at least 2 d (7-14 d typical) after signs and symptoms have disappeared.

Rifaximin (Xifaxan)


Nonabsorbed (< 0.4%), broad-spectrum antibiotic specific for enteric pathogens of the GI tract (ie, gram-positive, gram-negative, aerobic, anaerobic). Rifampin structural analog. Binds to beta-subunit of bacterial DNA-dependent RNA polymerase, thereby inhibiting RNA synthesis. Indicated for E coli (enterotoxigenic and enteroaggregative strains) associated with travelers' diarrhea.

Amoxicillin-clavulanate potassium (Augmentin)


Amoxicillin inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins. Addition of clavulanate inhibits beta-lactamase producing bacteria.

Good alternative antibiotic for patients allergic or intolerant to the macrolide class. Usually is well tolerated and provides good coverage to most infectious agents. Not effective against mycoplasmal and legionella species. The half-life of oral dosage form is 1-1.3 h. Has good tissue penetration but does not enter cerebrospinal fluid.

For children >3 months, base dosing protocol on amoxicillin content. Due to different amoxicillin/clavulanic acid ratios in 250-mg tab (250/125) vs 250-mg chewable tab (250/62.5), do not use 250-mg tab until child weighs >40 kg.


Proton Pump Inhibitors

Class Summary

Inhibit gastric acid secretion by inhibition of the H+/K+/ATP-ase enzyme system in the gastric parietal cells. These agents are used in cases of severe esophagitis and in patients not responding to H2-antagonist therapy.

Esomeprazole magnesium (Nexium)


S-isomer of omeprazole. Inhibits gastric acid secretion by inhibiting H+/K+-ATPase enzyme system at secretory surface of gastric parietal cells.

Used in severe cases and in patients not responding to H2 antagonist therapy.

Used for up to 4 wk to treat and relieve symptoms of active duodenal ulcers; may be used up to 8 wk to treat all grades of erosive esophagitis.

Contributor Information and Disclosures

Divyanshoo Rai Kohli, MD Fellow, Department of Gastroenterology, Hepatology and Nutrition, Virginia Commonwealth University School of Medicine

Divyanshoo Rai Kohli, MD is a member of the following medical societies: American College of Physicians

Disclosure: Nothing to disclose.


Timothy R Koch, MD Professor of Medicine (Gastroenterology), Georgetown University School of Medicine

Timothy R Koch, MD is a member of the following medical societies: American College of Gastroenterology, American Gastroenterological Association, American Physiological Society

Disclosure: Nothing to disclose.

Jennifer (Zone-En) Lee, MD Fellow, Section of Gastroenterology, Georgetown University School of Medicine, Washington Hospital Center

Jennifer (Zone-En) Lee, MD is a member of the following medical societies: American College of Gastroenterology, American Gastroenterological Association, American Society for Gastrointestinal Endoscopy

Disclosure: Nothing to disclose.

Specialty Editor Board

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

Chief Editor

BS Anand, MD Professor, Department of Internal Medicine, Division of Gastroenterology, Baylor College of Medicine

BS Anand, MD is a member of the following medical societies: American Association for the Study of Liver Diseases, American College of Gastroenterology, American Gastroenterological Association, American Society for Gastrointestinal Endoscopy

Disclosure: Nothing to disclose.

Additional Contributors

David Greenwald, MD Professor of Clinical Medicine, Fellowship Program Director, Department of Medicine, Division of Gastroenterology, Montefiore Medical Center, Albert Einstein College of Medicine

David Greenwald, MD is a member of the following medical societies: Alpha Omega Alpha, New York Society for Gastrointestinal Endoscopy, American College of Gastroenterology, American College of Physicians, American Gastroenterological Association, American Society for Gastrointestinal Endoscopy

Disclosure: Nothing to disclose.


Hiral Shah, MD Chief Resident, Department of Internal Medicine, Georgetown University Hospital at Washington Hospital Center

Hiral Shah, MD is a member of the following medical societies: American College of Gastroenterology, American College of Physicians, American Gastroenterological Association, and American Medical Association

Disclosure: Nothing to disclose.

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