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Telotristat Ethyl

Medically reviewed by Last updated on Nov 6, 2020.


(tel OH tri state ETH il)

Index Terms

  • LX1032
  • LX1606
  • Telotristat Etiprate
  • Xermelo

Dosage Forms

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Tablet, Oral:

Xermelo: 250 mg

Brand Names: U.S.

  • Xermelo

Pharmacologic Category

  • Tryptophan Hydroxylase Inhibitor


Telotristat ethyl is a small molecule inhibitor of tryptophan hydroxylase (TPH). TPH converts tryptophan to 5-hydroxytryptophan and ultimately to serotonin, and is the rate-limiting enzyme in serotonin synthesis (Kulke 2017). Decreased production of peripheral serotonin by telotristat ethyl results in a reduction in the frequency of carcinoid syndrome diarrhea.


The high molecular weight and acidic moieties of telotristat ethyl inhibit the compound from crossing the blood brain barrier (Kulke 2017).


Telotristat ethyl is hydrolyzed via carboxylesterases to the metabolite telotristat (active); telotristat is further metabolized.


Feces (~93%); urine (<1%)

Time to Peak

Telotristat ethyl: 0.5 to 2 hours; Telotristat: 1 to 3 hours

Half-Life Elimination

Telotristat ethyl: ~0.6 hours; Telotristat: ~5 hours

Protein Binding


Special Populations: Hepatic Function Impairment

Telotristat ethyl systemic exposure (AUC0-last) increased 2.3-, 3.2-, and 4-fold, respectively, and telotristat (active metabolite) systemic exposure (AUC0-last) increased 2.4-, 3.5-, and 5-fold, respectively, in patients with mild (Child-Pugh class A), moderate (Child-Pugh class B), or severe (Child-Pugh class C) impairment compared to patients with normal hepatic function.

Use: Labeled Indications

Carcinoid syndrome diarrhea: Treatment of carcinoid syndrome diarrhea (in combination with somatostatin analog therapy) in adults with symptoms inadequately controlled by somatostatin analog therapy


There are no contraindications listed in the US manufacturer's labeling.

Canadian labeling: Additional contraindications (not in US labeling): Hypersensitivity to telotristat ethyl or any component of the formulation.

Dosing: Adult

Carcinoid syndrome diarrhea: Oral: 250 mg 3 times daily

Missed dose: If a dose is missed, administer the next dose at the regularly scheduled time; do not take 2 doses at the same time.

Dosing: Geriatric

Refer to adult dosing.

Dosing: Adjustment for Toxicity

Gastrointestinal toxicity: Discontinue for severe constipation or for development of severe, persistent or worsening abdominal pain


Administer with food. If used in combination with short-acting octreotide, administer octreotide at least 30 minutes after telotristat ethyl. Rescue octreotide (short-acting) and antidiarrheals were allowed and unrestricted in a clinical study (Kulke 2017).


Store at 25°C (77°F); excursions permitted to 15°C to 30°C (59°F to 86°F).

Drug Interactions

CloZAPine: CYP3A4 Inducers (Weak) may decrease the serum concentration of CloZAPine. Monitor therapy

NiMODipine: CYP3A4 Inducers (Weak) may decrease the serum concentration of NiMODipine. Monitor therapy

Octreotide: May decrease the serum concentration of Telotristat Ethyl. Management: Administer short-acting octreotide at least 30 minutes after administration of telotristat ethyl and monitor for decreased telotristat ethyl efficacy. Consider therapy modification

Selpercatinib: CYP3A4 Inducers (Weak) may decrease the serum concentration of Selpercatinib. Monitor therapy

Tacrolimus (Systemic): CYP3A4 Inducers (Weak) may decrease the serum concentration of Tacrolimus (Systemic). Monitor therapy

Ubrogepant: CYP3A4 Inducers (Weak) may decrease the serum concentration of Ubrogepant. Management: Use an initial ubrogepant dose of 100 mg and second dose (if needed) of 100 mg when used with a weak CYP3A4 inducer. Consider therapy modification

Adverse Reactions

The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified.


Central nervous system: Headache (11%)

Gastrointestinal: Nausea (13%)

1% to 10%:

Cardiovascular: Peripheral edema (7%)

Central nervous system: Depression (9%)

Endocrine & metabolic: Increased gamma-glutamyl transferase (9%)

Gastrointestinal: Decreased appetite (7%), flatulence (7%), abdominal pain (≥5%), constipation (≥5%)

Hepatic: Increased serum alkaline phosphatase (<5%), increased serum ALT (<5%), increased serum AST (<5%)

Miscellaneous: Fever (7%)


Concerns related to adverse effects:

• Gastrointestinal toxicity: Constipation has been reported in clinical trials. Although rarely serious, some events resulted in hospitalization, intestinal perforation or bowel obstruction (these events occurred at a dose higher than the recommended dose). Patients with advanced carcinoid tumors may be at risk for altered gastrointestinal tract wall integrity; monitor closely for constipation and/or severe, persistent, or worsening abdominal pain. Discontinue for severe constipation and/or the development of severe persistent or worsening abdominal pain.

Disease-related concerns:

• Hepatic impairment: Additional monitoring for GI effects (eg, constipation) recommended in patients with mild impairment. Use not recommended in moderate to severe impairment.

Monitoring Parameters

Monitor for symptoms of constipation and/or severe, persistent, or worsening abdominal pain

Pregnancy Considerations

Adverse events were observed in some animal reproduction studies.

Patient Education

What is this drug used for?

• It is used to treat carcinoid syndrome diarrhea.

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

• Nausea

• Headache

• Passing gas

• Lack of appetite

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

• Severe constipation

• Severe abdominal pain

• Depression

• Swelling in the arms or legs

• Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.

Note: This is not a comprehensive list of all side effects. Talk to your doctor if you have questions.

Consumer Information Use and Disclaimer: This information should not be used to decide whether or not to take this medicine or any other medicine. Only the healthcare provider has the knowledge and training to decide which medicines are right for a specific patient. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a limited summary of general information about the medicine’s uses from the patient education leaflet and is not intended to be comprehensive. This limited summary does NOT include all information available about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not intended to provide medical advice, diagnosis or treatment and does not replace information you receive from the healthcare provider. For a more detailed summary of information about the risks and benefits of using this medicine, please speak with your healthcare provider and review the entire patient education leaflet.

Frequently asked questions

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.