Pepsin is a protease indicated in the treatment of digestive disorders.

Generic Name
DrugBank Accession Number

Pepsin is a potent enzyme in gastric juice that digests proteins such as those in meat, eggs, seeds, and dairy products 12.

Studies on gastric digestion from 1820-1840 led to the discovery of pepsin as the substance which, in the presence of stomach acid, causes nutrients including meat or coagulated egg whites to dissolve. Soon afterward, it was shown that these protein nutrients were cleaved by pepsin to products called peptones 2.

Pepsin is often used as a replacement enzyme for those with pancreatic insufficiency 11. Stimulation of the pancreas and therefore enzymatic digestion of food is a tightly controlled and is a hormonally mediated process. Any changes or conditions affecting metabolic steps for successful digestion and absorption negatively affect pancreatic enzymatic secretion, entry into the intestine, functionality once inside the intestine, and appropriate mixing with foods/nutrients. Many causes of pancreatic insufficiency require that enzyme replacement therapy is started, including cystic fibrosis, pancreatic cancer, acute and chronic pancreatitis, as well as pancreatic surgery 11.

Pepsin is approved by the FDA and is used in food at levels not to exceed current good manufacturing practice 17. Interestingly, it has been used as a marker for laryngopharyngeal reflux (LPR), which is a common illness of otolaryngology (ear, nose and throat specialist) visits 3.

Interestingly, recent research has suggested that pepsin participates in the digestion of nucleic acids 22.

Approved, Experimental, Investigational
Biologic Classification
Protein Based Therapies
Other protein based therapies
Protein Chemical Formula
Not Available
Protein Average Weight
Not Available
> Pepsin A Sus Scrofa (Pig)
Download FASTA Format
  • Lactated pepsin
  • Pepsin A
  • Pepsin porcine
  • Pepsin, bovine
  • Pepsina
  • Saccharated pepsin



Used as a pancreatic enzyme replacement in pancreatic insufficiency 11. It is intended to mimic naturally produced human pepsin 14.

Pepsin powder is prepared from the gastric mucosa of pigs, cattle or sheep 19. In the laboratory, it is primarily used for the unspecific hydrolysis of proteins and peptides in acidic media. In addition, it provides limited hydrolysis of native immunoglobulins, yielding biologically active fragments 7.

In certain supplements, pepsin may be combined with betaine and HCl (hydrochloric acid) to aid in digestion in various gastrointestinal conditions 14, 6.

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Pepsin digests protein 12. It classified by the FDA that is characterizing enzyme activity is that of a peptide hydrolase 17.

Mechanism of action

Glands present in the mucous membrane lining of the stomach produce and store an inactive protein named pepsinogen. Impulses from the vagus nerve and the hormonal secretions of the hormones gastrin and secretin promote the release of pepsinogen into the stomach, where it is mixed with hydrochloric acid and quickly converted to the active enzyme pepsin. The digestive potency of pepsin is highest at the acidic pH of normal gastric juice. In the intestine, the gastric acids are then neutralized, and pepsin is no longer effective 12.

Pepsin, the proteolytic enzyme of the stomach is normally responsible for less than 20% of the protein digestion occuring the gastrointestinal tract. It is an endopeptidase enzyme that metabolizes proteins to peptides. It preferentially hydrolyzes peptide linkages where one of the amino acids is aromatic. Pepsin, like other protease enzymes, is produced from an inactive precursor, pepsinogen, which is stored in granule form in the chief cells of the stomach and are released by a process called exocytosis 16.

In the digestive tract, pepsin activity only contributes to the partial breakdown of proteins into smaller units called peptides, which then either are absorbed from the intestine into the bloodstream or are broken down further by pancreatic enzymes 12.


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Volume of distribution

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Protein binding

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Pepsin is the first of several enzymes that digest proteins. In the stomach, polypeptide chains bind in the deep active site groove of pepsin, and are then digested into smaller pieces. Following this, a variety of proteases and peptidases in the intestine complete the process. The small fragments, which are amino acids and dipeptides, are then absorbed by cells for use as metabolic energy or construction of new proteins 15.

Route of elimination

Not Available


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Adverse Effects
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Oral LD50 Rat 90000 mg/kg MSDS

Chronic backflow of pepsin, acid, and other substances from the stomach into the esophagus, is the basis of reflux conditions, particularly gastroesophageal reflux disease (GERD) and laryngopharyngeal reflux. In the latter, pepsin and acid travel all the way up to the larynx, where they can lead to damage of the laryngeal mucosa and lead to symptoms ranging from hoarseness of the voice and chronic cough to laryngospasm (involuntary contraction of the vocal cords) as well as laryngeal cancer 12.

Though limited data is available on the toxicity of exogenous pepsin (not naturally produced in one's gastrointestinal tract), it can be extrapolated from the above-mentioned information that pepsin overdose may lead to mucosal tissue damage of the gastrointestinal tract.

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Pharmacogenomic Effects/ADRs
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Drug Interactions
This information should not be interpreted without the help of a healthcare provider. If you believe you are experiencing an interaction, contact a healthcare provider immediately. The absence of an interaction does not necessarily mean no interactions exist.
Not Available
Food Interactions
  • Drink plenty of fluids.
  • Take before a meal.


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Over the Counter Products
NameDosageStrengthRouteLabellerMarketing StartMarketing EndRegionImage
DigestexLiquid100 mg / 30 mLOralTheralab Inc.1981-04-252000-08-01Canada flag
Mixture Products
NameIngredientsDosageRouteLabellerMarketing StartMarketing EndRegionImage
Bemosin TabPepsin (130 mg) + Ammonium chloride (97.2 mg) + Betaine hydrochloride (130 mg)TabletOralTherapeutic Foods Co.1988-12-312003-07-16Canada flag
Betaine HCl and PepsinPepsin (135 mg) + Betaine hydrochloride (324 mg)TabletOralRheingold Food International Ltd.1985-12-312007-07-26Canada flag
Betasin TabPepsin (130 mg / tab) + Ammonium chloride (97.2 mg / tab) + Betaine hydrochloride (130 mg / tab)TabletOralBio Vita1987-12-311996-09-09Canada flag
DebilinePepsin (50 mg) + Deoxycholic acid (100 mg)TabletOralLab Nadeau LtÉe, Division Of Technilab Inc.1951-12-311999-09-28Canada flag
Debiline HPepsin (50 mg / tab) + Deoxycholic acid (100 mg / tab) + Homatropine methylbromide (2.5 mg / tab)TabletOralLab Nadeau LtÉe, Division Of Technilab Inc.1951-12-311999-09-28Canada flag
Duchol EctPepsin (200 mg) + Dehydrocholic acid (30 mg) + Deoxycholic acid (30 mg) + Pancrelipase (200 mg) + Sodium taurocholate (100 mg)Tablet, delayed releaseOralDuchesnay Inc.1977-12-312003-07-18Canada flag
DygestPepsin (125 mg) + Betaine hydrochloride (90 mg) + Ox bile extract (75 mg) + Pancrelipase (200 mg) + Papain (100 mg) + Peppermint (50 mg)TabletOralCreative Nutrition Canada Corp.1987-12-312007-07-11Canada flag
Enzyme TabletsPepsin (65 mg) + Betaine hydrochloride (65 mg) + Ox bile extract (8.125 mg) + Pancrelipase (100 mg) + Pancrelipase amylase (130 mg) + Papain (65 mg)TabletOralGeneral Nutrition Canada Inc.2001-10-202007-08-01Canada flag
Glutamic Acid HCl Betaine HCl W PepsinPepsin (100 mg / tab) + Betaine hydrochloride (100 mg / tab) + Glutamic acid hydrochloride (200 mg / tab)TabletOralNu Life Nutrition Ltd.1963-12-312000-03-03Canada flag
Glutamic Acid Hydrochloride Nu LifePepsin (65 mg) + Glutamic acid hydrochloride (500 mg)TabletOralNu Life Nutrition Ltd.1963-12-312005-03-15Canada flag


ATC Codes
A09AC01 — Pepsin and acid preparationsA09AA03 — Pepsin
Drug Categories
Chemical TaxonomyProvided by Classyfire
Not Available
Organic Compounds
Super Class
Organic Acids
Carboxylic Acids and Derivatives
Sub Class
Amino Acids, Peptides, and Analogues
Direct Parent
Alternative Parents
Not Available
Not Available
Molecular Framework
Not Available
External Descriptors
Not Available
Affected organisms
  • Humans and other mammals

Chemical Identifiers

CAS number


General References
  1. Iannella G, Di Nardo G, Plateroti R, Rossi P, Plateroti AM, Mariani P, Magliulo G: Investigation of pepsin in tears of children with laryngopharyngeal reflux disease. Int J Pediatr Otorhinolaryngol. 2015 Dec;79(12):2312-5. doi: 10.1016/j.ijporl.2015.10.034. Epub 2015 Oct 30. [Article]
  2. Fruton JS: A history of pepsin and related enzymes. Q Rev Biol. 2002 Jun;77(2):127-47. [Article]
  3. Calvo-Henriquez C, Ruano-Ravina A, Vaamonde P, Martinez-Capoccioni G, Martin-Martin C: Is Pepsin a Reliable Marker of Laryngopharyngeal Reflux? A Systematic Review. Otolaryngol Head Neck Surg. 2017 Sep;157(3):385-391. doi: 10.1177/0194599817709430. Epub 2017 Jun 6. [Article]
  4. Petersen KU: Pepsin and Its Importance for Functional Dyspepsia: Relic, Regulator or Remedy? Dig Dis. 2018;36(2):98-105. doi: 10.1159/000481399. Epub 2017 Oct 5. [Article]
  5. Hedemann MS, Jensen BB: Variations in enzyme activity in stomach and pancreatic tissue and digesta in piglets around weaning. Arch Anim Nutr. 2004 Feb;58(1):47-59. [Article]
  6. Nutritional Interventions for Gastroesophageal Reflux, Irritable Bowel Syndrome, and Hypochlorhydria: A Case Report [Link]
  7. Pepsin, Sigma Aaldrich [Link]
  8. Effect of Pepsin on the Absorption of Food Vitamin B12 and Iron [Link]
  9. Pepsin [Link]
  10. Pepsin: topics [Link]
  11. Pancreatic Enzyme Replacement Therapy During Pancreatic Insufficiency [Link]
  12. Pepsin [Link]
  13. Gastritis [Link]
  14. Zypan [Link]
  15. PDB-pepsin [Link]
  16. NIH Dictionary- Pepsin [Link]
  17. Code of Federal Regulations, Pepsin [Link]
  18. Pepsin Drug Monograph [Link]
  19. Pepsin, [Link]
  20. Determining the Safety of Enzymes Used in Food Processing [Link]
  22. Digestion of Nucleic Acids Starts in the Stomach [Link]
PubChem Substance
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Clinical Trials

Clinical Trials
Not AvailableCompletedNot AvailableAbdominal Pain / Dyspepsia / Flatulence / Functional Gastrointestinal Disorders (FGID) / Nausea / Vomiting1


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Dosage Forms
LiquidOral100 mg / 30 mL
Tablet, delayed releaseOral
Tablet, film coatedOral
Not Available
Not Available


Experimental Properties
water solubilityvery soluble MSDS

Drug created at June 23, 2017 20:37 / Updated at June 05, 2021 09:12