Accession NumberDB00581  (APRD01063)
TypeSmall Molecule

A synthetic disaccharide used in the treatment of constipation and hepatic encephalopathy. It has also been used in the diagnosis of gastrointestinal disorders. (From Martindale, The Extra Pharmacopoeia, 30th ed, p887)

External IDs Not Available
Product Ingredients Not Available
Approved Prescription ProductsNot Available
Approved Generic Prescription Products
NameDosageStrengthRouteLabellerMarketing StartMarketing End
ConstuloseSolution10 g/15mLOralActavis, Inc.2011-02-28Not applicableUs
EnuloseSolution10 g/15mLOral; RectalActavis, Inc.2011-02-28Not applicableUs
GenerlacSolution10 g/15mLOralMorton Grove Pharmaceuticals, Inc.1996-10-31Not applicableUs
KristalosePowder, for solution10 g/10gOralCumberland Pharmaceuticals2012-01-20Not applicableUs
KristalosePowder, for solution20 g/20gOralCumberland Pharmaceuticals2012-01-20Not applicableUs
LactuloseSolution10 g/15mLOralPhysicians Total Care, Inc.2004-04-19Not applicableUs
LactuloseSolution10 g/15mLOralRoxane Laboratories1992-05-292016-10-13Us
LactuloseSolution10 g/15mLOralWest Ward Pharmaceutical1992-05-29Not applicableUs
LactuloseSolution10 g/15mLOralPharmaceutical Associates, Inc.1966-07-30Not applicableUs
LactuloseSolution10 g/15mLOralHi Tech Pharmacal Co., Inc.1995-07-03Not applicableUs
LactuloseSolution20 g/30mLOralVista Pharm, Inc.2010-05-10Not applicableUs
LactuloseSolution10 g/15mLOralRebel Distributors2004-04-19Not applicableUs
LactuloseSolution10 g/15mLOralA S Medication Solutions2001-07-262017-06-20Us
LactuloseSolution10 g/15mLOralFresenius Kabi Austria Gmb H2012-12-10Not applicableUs
LactuloseSolution10 g/15mLOralAidarex Pharmaceuticals LLC1995-07-03Not applicableUs
LactuloseSolution10 g/15mLOralMorton Grove Pharmaceuticals, Inc.1996-11-14Not applicableUs
LactuloseSolution10 g/15mLOralNucare Pharmaceuticals, Inc.1966-07-30Not applicableUs
LactuloseSolution10 g/15mLOral; RectalHi Tech Pharmacal Co., Inc.1995-07-03Not applicableUs
LactuloseSolution10 g/15mLOralVista Pharm, Inc.2010-05-10Not applicableUs
LactuloseSolution20 g/30mLOralCardinal Health2010-05-10Not applicableUs
LactuloseSolution10 g/15mLOralQualitest2001-07-26Not applicableUs
LactuloseSolution10 g/15mLOralCardinal Health1966-07-30Not applicableUs
LactuloseSolution10 g/15mLOralPharmaceutical Associates, Inc.1966-07-30Not applicableUs
LactuloseSolution10 g/15mLOralLake Erie Medical Dba Quality Care Produts Llc2001-07-26Not applicableUs
LactuloseSolution10 g/15mLOralCardinal Health1966-07-30Not applicableUs
LactuloseSolution10 g/15mLOralLake Erie Medical &Surgical Supply Dba Quality Care Products Llc2004-04-19Not applicableUs
LactuloseSolution20 g/30mLOralPharmaceutical Associates, Inc.1966-07-30Not applicableUs
LactuloseSolution10 g/15mLOralUnit Dose Services1995-07-03Not applicableUs
LactuloseSolution10 g/15mLOralCardinal Health1996-07-30Not applicableUs
LactuloseSolution10 g/15mLOralAtlantic Biologicals Corps.2001-07-26Not applicableUs
LactuloseLiquid10 g/15mLOral; RectalPatrin Pharma2016-09-01Not applicableUs
LactuloseSolution10 g/15mLOral; RectalFresenius Kabi Austria Gmb H2012-12-10Not applicableUs
LactuloseSolution10 g/15mLOralMc Kesson Packaging Services A Buisness Unit Of Mc Kesson Corporation2011-11-012017-04-15Us
LactuloseSolution10 g/15mLOralCardinal Health1966-07-30Not applicableUs
Approved Over the Counter Products
NameDosageStrengthRouteLabellerMarketing StartMarketing End
Apo-lactuloseLiquid667 mgOralApotex Corporation2001-02-19Not applicableCanada
Cephulac Syr 667mg/mlSyrup667 mgOralHoechst Marion Roussel1995-12-311998-08-12Canada
Chronulac SyrSyrup667 mgOral; OtherMerrell Pharms Inc., Division Of Merrell Dow (Can)1977-12-311996-09-09Canada
Chronulac Syr 667mg/mlSyrup667 mgOralHoechst Marion Roussel1996-12-311998-08-12Canada
Comalose R Sirop 10gm/15mlSyrup10 gOral; RectalRougier Pharma Division Of Ratiopharm Inc1987-12-311999-09-27Canada
DuphalacPowder95 gOralSolvay Pharma Inc1997-11-272001-02-12Canada
Duphalac DryPowder950 mgOralSolvay Pharma Inc1996-07-231998-08-04Canada
Gen-lac - Liq 667mg/mlLiquid667 mgOralGenpharm Ulc1990-12-312009-08-05Canada
Jamp-lactuloseSyrup667 mgOralOrbus Pharma Inc2006-11-072010-03-31Canada
Jamp-lactuloseSolution667 mgOralJamp Pharma Corporation2008-06-20Not applicableCanada
Lactulax Sirop 10gm/15mlSyrup10 gOralRougier Pharma Division Of Ratiopharm Inc1987-12-311999-09-27Canada
LactuloseSolution667 mgOral9113657 Canada IncNot applicableNot applicableCanada
LactuloseSyrup667 mgOralSanis Health Inc2013-10-09Not applicableCanada
Lactulose Solution USP - Liq 667mg/mlLiquid667 mgOralBdh Inc.1995-12-311999-08-11Canada
Lactulose Solution, USP 667mg/mlSolution10 gOralMarcan Pharmaceuticals IncNot applicableNot applicableCanada
Lactulose SyrupSyrup10 gOralStanley Pharmaceuticals, A Division Of Vita Health Products Inc.1989-12-311997-08-08Canada
M-lactuloseSolution667 mgOralMantra Pharma IncNot applicableNot applicableCanada
Orb-lactuloseSyrup667 mgOralOrbus Pharma IncNot applicableNot applicableCanada
Pharma-lactuloseSolution667 mgOralPharmascience Inc2004-06-23Not applicableCanada
PHL-lactulose Soln 667mg/mlSolution667 mgOralPharmel IncNot applicableNot applicableCanada
PMS-lactulose Syr 667mg/mlSyrup667 mgOralPharmascience Inc1996-10-16Not applicableCanada
Pro-lactulose - 667Solution667 mgOralPro Doc Limitee2008-07-042011-07-27Canada
Ratio-lactuloseSolution667 mgOralTeva1986-12-31Not applicableCanada
Ratio-lactuloseSolution667 mgOralRatiopharm Inc Division Of Teva Canada Limited1996-07-302009-07-17Canada
Ratio-lactuloseSolution667 mgOralRatiopharm Inc Division Of Teva Canada Limited1987-12-312009-07-17Canada
Teva-lactuloseSolution667 mgOralTeva2010-11-15Not applicableCanada
Woodward's Laxative SyrupSyrup3.3 gOralPharmacare Ltd., South AfricaNot applicableNot applicableCanada
Unapproved/Other Products Not Available
International Brands
CephulacNot Available
ChronulacNot Available
Brand mixturesNot Available
CAS number4618-18-2
WeightAverage: 342.2965
Monoisotopic: 342.116211546
Chemical FormulaC12H22O11
OC[[email protected]]1O[C@](O)(CO)[C@@H](O)[C@@H]1O[C@@H]1O[[email protected]](CO)[[email protected]](O)[[email protected]](O)[[email protected]]1O

For the treatment of constipation and hepatic encephalopathy.

Structured Indications

Therapeutically, lactulose has laxative and ammonia-detoxifying actions. In treating constipation lactulose metabolites draw water into the bowel, causing a cathartic effect through osmotic action.

Mechanism of action

Lactulose is a synthetic sugar used in the treatment of constipation and liver disease. It consists of the monosaccharides fructose and galactose. In the colon, lactulose is broken down primarily to lactic acid, and also to small amounts of formic and acetic acids, by the action of via evolved-beta galactosidase from colonic bacteria, which results in an increase in osmotic pressure and slight acidification of the colonic contents. This in turn causes an increase in stool water content and softens the stool. In treating heptic diseases (hepatic encephalopathy) it is thought that lactulose draws out ammonia from the body in the same way that it draws out water into the colon.

TargetKindPharmacological actionActionsOrganismUniProt ID
Evolved beta-galactosidase subunit alphaProteinyes
Escherichia coli (strain K12)P06864 details
Related Articles

Poorly absorbed from the gastrointestinal tract as no human enzyme that is capable of hydrolysis of this disaccharide is present in human gastrointestinal tissue.

Volume of distributionNot Available
Protein bindingNot Available

Lactulose is completely metabolized in the colon by enteric bacteria, and no lactulose is excreted in the feces.

Route of elimination

The primary route of elimination is fecal. Urinary excretion has been determined to be 3% or less and is essentially complete within 24 hours.

Half life

1.7-2 hours

ClearanceNot Available

LD50=18.2 g/kg (oral, rat). Side effects include diarrhea and resultant dehydration.

Affected organisms
  • Humans and other mammals
PathwaysNot Available
Pharmacogenomic Effects/ADRs Not Available
Drug Interactions
DrugInteractionDrug group
L-GlutamineThe therapeutic efficacy of Lactulose can be decreased when used in combination with L-Glutamine.Approved, Investigational, Nutraceutical
Food Interactions
  • Take without regard to meals. Drink liberally.
Synthesis Reference

Renato Carobbi, Franco Innocenti, "Process for preparing high-purity lactulose syrup and the syrup obtained." U.S. Patent US4978397, issued April, 1961.

General ReferencesNot Available
External Links
ATC CodesA06AD61 — Lactulose, combinationsA06AD11 — Lactulose
AHFS Codes
  • 40:10.00
PDB EntriesNot Available
FDA labelNot Available
MSDSDownload (73.6 KB)
Clinical Trials
Clinical Trials
1CompletedTreatmentBowel Evacuant Prior to Colonoscopy1
1CompletedTreatmentOpiate Addiction1
2CompletedPreventionNecrotizing Enterocolitis / Sepsis1
2CompletedTreatmentChronic Constipation1
2CompletedTreatmentFeces, Impacted1
2CompletedTreatmentHepatic Encephalopathy1
2CompletedTreatmentHepatic Encephalopathy / Liver Cirrhosis / Portal Hypertension1
2CompletedTreatmentOccasional Constipation1
2TerminatedTreatmentMinimal Hepatic Encephalopathy1
2Unknown StatusTreatmentHepatic Encephalopathy1
2, 3CompletedTreatmentChronic Liver Diseases (CLD) / Hepatic Encephalopathy1
2, 3CompletedTreatmentModerate, refractory Atopic dermatitis1
2, 3RecruitingTreatmentHepatic Encephalopathy1
3CompletedTreatmentChronic Constipation1
3Unknown StatusPreventionEncephalopathy, Hepatocerebral / Hepatic Encephalopathy / Portal-Systemic Encephalopathy1
3WithdrawnTreatmentHepatic Encephalopathy1
4CompletedPreventionHepatic Encephalopathy1
4CompletedTreatmentHepatic Encephalopathy / Liver Cirrhosis1
4CompletedTreatmentHepatic Encephalopathy / Minimal Hepatic Encephalopathy1
4CompletedTreatmentOccasional Constipation2
4RecruitingTreatmentHepatic Encephalopathy1
4RecruitingTreatmentOccasional Constipation1
4RecruitingTreatmentOccasional Constipation / Peritoneal dialysis complication1
4TerminatedTreatmentAnal Fissures / Hemorrhoids1
4TerminatedTreatmentHepatic Encephalopathy / Liver Cirrhosis / Portal Hypertension1
4Unknown StatusNot AvailableHepatic Encephalopathy1
4Unknown StatusTreatmentHepatic Encephalopathy2
4Unknown StatusTreatmentLiver Cirrhosis / Renal Failure1
Not AvailableCompletedBasic ScienceInsulin Resistance / Prediabetic State1
Not AvailableCompletedDiagnosticHepatic Encephalopathy1
Not AvailableCompletedDiagnosticHepatic Encephalopathy / Liver Cirrhosis1
Not AvailableCompletedPreventionLiver Cirrhosis1
Not AvailableCompletedTreatmentAcute on Chronic Liver Failure With Hepatic Encephalopathy / Acute-On-Chronic Liver Failure1
Not AvailableCompletedTreatmentCirrhosis Related Parkinsonism / Hepatic/Cirrhosis Related Parkinsonism1
Not AvailableCompletedTreatmentHepatic Encephalopathy2
Not AvailableCompletedTreatmentHepatic Encephalopathy / Liver Cirrhosis / Portosystemic Encephalopathy / PSE1
Not AvailableRecruitingTreatmentLiver Cirrhosis1
Not AvailableRecruitingTreatmentRefractory Hepatic Encephalopathy1
Not AvailableUnknown StatusDiagnosticHirschsprung's Disease1
Not AvailableUnknown StatusPreventionHospital Acquired Infections1
Not AvailableUnknown StatusTreatmentAbdominal Pain (AP) / Nausea / Occasional Constipation / Vomiting1
Not AvailableUnknown StatusTreatmentOccasional Constipation1
Not AvailableWithdrawnTreatmentAltered Mental Status / AMS / HE / Hepatic Encephalopathy / Liver Cirrhosis1
  • Inalco spa
  • Sanofi aventis us llc
  • Alra laboratories inc
  • Actavis mid atlantic llc
  • Solvay pharmaceuticals
  • Teva pharmaceuticals usa
  • Ani pharmaceuticals inc
  • Hi tech pharmacal co inc
  • Morton grove pharmaceuticals inc
  • Novex pharma
  • Paco pharmaceutical services inc
  • Pharmaceutical assoc inc div beach products
  • Roxane laboratories inc
  • Vintage pharmaceuticals inc
  • Vistapharm inc
  • Nostrum laboratories inc
Dosage forms
LiquidOral667 mg
SyrupOral; Other667 mg
SyrupOral; Rectal10 g
PowderOral95 g
PowderOral950 mg
SolutionOral; Rectal10 g/15mL
SolutionOral667 mg
Powder, for solutionOral10 g/10g
Powder, for solutionOral20 g/20g
SyrupOral10 g
LiquidOral; Rectal10 g/15mL
SolutionOral10 g/15mL
SolutionOral20 g/30mL
SyrupOral667 mg
SolutionOral10 g
SyrupOral3.3 g
Unit descriptionCostUnit
Kristalose 30 20 gm Packets Box83.93USD box
Kristalose 30 10 gm Packets Box57.57USD box
Enulose 10 gm/15ml Solution 473ml Bottle37.83USD bottle
Kristalose 20 gm packet2.04USD each
Kristalose 10 gm packet1.67USD each
Constulose 10 gm/15 ml soln0.09USD ml
Enulose 10 gm/15 ml solution0.08USD ml
Lactulose Encephalopathy 10 gm/15ml Solution0.08USD ml
Lactulose 10 gm/15ml Solution0.07USD ml
Generlac 10 gm/15 ml solution0.05USD ml
Apo-Lactulose 667 mg/ml Syrup0.02USD ml
Jamp-Lactulose 667 mg/ml Syrup0.02USD ml
Pms-Lactulose 667 mg/ml Syrup0.02USD ml
Ratio-Lactulose 667 mg/ml Syrup0.02USD ml
DrugBank does not sell nor buy drugs. Pricing information is supplied for informational purposes only.
PatentsNot Available
Experimental Properties
melting point (°C)169 °CPhysProp
water solubility7.64E+005 mg/L (at 30 °C)MERCK (1989)
logP-4.3Not Available
Predicted Properties
Water Solubility792.0 mg/mLALOGPS
pKa (Strongest Acidic)10.28ChemAxon
pKa (Strongest Basic)-3ChemAxon
Physiological Charge0ChemAxon
Hydrogen Acceptor Count11ChemAxon
Hydrogen Donor Count8ChemAxon
Polar Surface Area189.53 Å2ChemAxon
Rotatable Bond Count5ChemAxon
Refractivity68.77 m3·mol-1ChemAxon
Polarizability31.49 Å3ChemAxon
Number of Rings2ChemAxon
Rule of FiveNoChemAxon
Ghose FilterNoChemAxon
Veber's RuleNoChemAxon
MDDR-like RuleNoChemAxon
Predicted ADMET features
Human Intestinal Absorption-0.8407
Blood Brain Barrier+0.6609
Caco-2 permeable-0.8957
P-glycoprotein substrateNon-substrate0.5805
P-glycoprotein inhibitor INon-inhibitor0.8575
P-glycoprotein inhibitor IINon-inhibitor0.9425
Renal organic cation transporterNon-inhibitor0.849
CYP450 2C9 substrateNon-substrate0.8745
CYP450 2D6 substrateNon-substrate0.854
CYP450 3A4 substrateNon-substrate0.6605
CYP450 1A2 substrateNon-inhibitor0.9472
CYP450 2C9 inhibitorNon-inhibitor0.9556
CYP450 2D6 inhibitorNon-inhibitor0.9386
CYP450 2C19 inhibitorNon-inhibitor0.9134
CYP450 3A4 inhibitorNon-inhibitor0.9774
CYP450 inhibitory promiscuityLow CYP Inhibitory Promiscuity0.9619
Ames testNon AMES toxic0.9421
BiodegradationNot ready biodegradable0.6719
Rat acute toxicity1.2563 LD50, mol/kg Not applicable
hERG inhibition (predictor I)Weak inhibitor0.9692
hERG inhibition (predictor II)Non-inhibitor0.8684
ADMET data is predicted using admetSAR, a free tool for evaluating chemical ADMET properties. (23092397 )
Mass Spec (NIST)Not Available
Spectrum TypeDescriptionSplash Key
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 10V, PositiveNot Available
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 20V, PositiveNot Available
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 40V, PositiveNot Available
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 10V, NegativeNot Available
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 20V, NegativeNot Available
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 40V, NegativeNot Available
DescriptionThis compound belongs to the class of organic compounds known as o-glycosyl compounds. These are glycoside in which a sugar group is bonded through one carbon to another group via a O-glycosidic bond.
KingdomOrganic compounds
Super ClassOrganic oxygen compounds
ClassOrganooxygen compounds
Sub ClassCarbohydrates and carbohydrate conjugates
Direct ParentO-glycosyl compounds
Alternative ParentsDisaccharides / C-glycosyl compounds / Oxanes / Tetrahydrofurans / Secondary alcohols / Hemiacetals / Polyols / Oxacyclic compounds / Acetals / Primary alcohols
SubstituentsO-glycosyl compound / Disaccharide / C-glycosyl compound / Oxane / Tetrahydrofuran / Secondary alcohol / Hemiacetal / Oxacycle / Organoheterocyclic compound / Polyol
Molecular FrameworkAliphatic heteromonocyclic compounds
External Descriptorsglycosylfructose (CHEBI:6359 )


Escherichia coli (strain K12)
Pharmacological action
General Function:
Carbohydrate binding
Specific Function:
The wild-type enzyme is an ineffective lactase. Two classes of point mutations dramatically improve activity of the enzyme.
Gene Name:
Uniprot ID:
Uniprot Name:
Evolved beta-galactosidase subunit alpha
Molecular Weight:
117878.225 Da
  1. Overington JP, Al-Lazikani B, Hopkins AL: How many drug targets are there? Nat Rev Drug Discov. 2006 Dec;5(12):993-6. [PubMed:17139284 ]
  2. Imming P, Sinning C, Meyer A: Drugs, their targets and the nature and number of drug targets. Nat Rev Drug Discov. 2006 Oct;5(10):821-34. [PubMed:17016423 ]
  3. Bjarnason I, Batt R, Catt S, Macpherson A, Maxton D, Menzies IS: Evaluation of differential disaccharide excretion in urine for non-invasive investigation of altered intestinal disaccharidase activity caused by alpha-glucosidase inhibition, primary hypolactasia, and coeliac disease. Gut. 1996 Sep;39(3):374-81. [PubMed:8949640 ]
  4. Cook GC: Breath hydrogen concentrations after oral lactose and lactulose in tropical malabsorption and adult hypolactasia. Trans R Soc Trop Med Hyg. 1978;72(3):277-81. [PubMed:97820 ]
  5. Noone C, Menzies IS, Banatvala JE, Scopes JW: Intestinal permeability and lactose hydrolysis in human rotaviral gastroenteritis assessed simultaneously by non-invasive differential sugar permeation. Eur J Clin Invest. 1986 Jun;16(3):217-25. [PubMed:3089818 ]
  6. Hall BG, Malik HS: Determining the evolutionary potential of a gene. Mol Biol Evol. 1998 Aug;15(8):1055-61. [PubMed:9718732 ]
Drug created on June 13, 2005 07:24 / Updated on July 18, 2017 16:50