Mounjaro (tirzepatide) is licensed for type 2 diabetes and, at higher doses, for chronic weight management.
Unlike earlier GLP-1 therapies, tirzepatide is a dual agonist, acting on two separate hormone receptor pathways.
This article explains the mechanism in clinical terms.

A dual mechanism
Tirzepatide activates both the GIP (glucose-dependent insulinotropic polypeptide) receptor and the GLP-1
(glucagon-like peptide-1) receptor. Both are naturally occurring incretin hormones released from the gut in
response to food intake. By acting on both pathways simultaneously, tirzepatide produces a combined metabolic
effect that has shown greater efficacy in clinical trials than single-pathway GLP-1 agonists alone.
Site-by-site effects
● Brain: reduces appetite and increases satiety signalling via hypothalamic pathways
● Pancreas: enhances glucose-dependent insulin secretion and suppresses inappropriate glucagon release
● Stomach: slows gastric emptying, prolonging the sensation of fullness after meals
● Peripheral tissue: GIP receptor activity is also associated with improved insulin sensitivity
Administration and dosing
Tirzepatide is administered as a once-weekly subcutaneous injection. Treatment begins at a low starting dose,
which is increased gradually — typically every four weeks — according to tolerability and response, up to the
target maintenance dose agreed with the prescribing clinician.

What patients should know
Gastrointestinal side effects — nausea, reduced appetite, constipation, or diarrhoea — are most common during
dose escalation and typically improve over time. As with all GLP-1/GIP-based therapies, tirzepatide requires a
documented clinical assessment before initiation, including screening for contraindications such as a personal or
family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2.
Ready to find out if this is right for you?
Stemax Consult provides CQC-accredited, GMC-led assessment and prescribing for tirzepatide treatment at our
Milton Keynes and Aberdeen sites. Call us today on 01908 032992 to book a consultation and find out if
Mounjaro is clinically appropriate for you.
This article is provided for general clinical information and does not constitute individual medical advice.
Patients should discuss suitability for treatment with a registered healthcare professional.