GIP/GLP-1 Dual Agonists Titration & Tapering Algorithms

What counts as a GIP/GLP-1 dual agonist?

Tirzepatide (Mounjaro and Zepbound) is labeled by FDA as a dual GIP and GLP-1 receptor agonist, a dual agonist rather than a pure GLP-1 agonist [1][5].

The rest of the family is single-receptor. Semaglutide (Ozempic, Wegovy, Rybelsus), liraglutide (Victoza, Saxenda), dulaglutide (Trulicity) and orforglipron (Foundayo) activate the GLP-1 receptor [2][3][7]. Their labeled schedules belong to those products, not to tirzepatide.

Retatrutide and cagrilintide are not FDA approved, and FDA states that neither can be used in compounding under federal law [8].

How the labeled titration runs

Tirzepatide is injected under the skin once weekly [1]. The Zepbound label's recommended starting dosage for all indications is 2.5 mg once weekly for 4 weeks. After 4 weeks the dosage is increased to 5 mg once weekly, and it may then be increased in 2.5 mg increments after at least 4 weeks on the current dose [1]. The maximum dosage for all indications is 15 mg once weekly [1].

Maintenance dosing depends on the indication. For weight reduction the recommended maintenance dosage is 5 mg, 10 mg or 15 mg once weekly; for obstructive sleep apnea it is 10 mg or 15 mg once weekly [1]. For a missed dose, the label says to give it as soon as possible within 4 days (96 hours) after the missed dose; if more than 4 days have passed, skip it and give the next dose on the regularly scheduled day [1].

The labels use the low start and gradual ramp to reduce gastrointestinal adverse reactions, which are the common class effect and are worst during dose escalation [1][2][3]. The trials followed the same ramp: SURMOUNT-1 assigned adults with obesity to 5, 10 or 15 mg once weekly and used a 20-week dose-escalation period to reach the assigned dose [9], and SURPASS-2 compared the same three once-weekly doses over 40 weeks in type 2 diabetes [10].

At the highest labeled Zepbound dose, 15 mg once weekly, trials of up to 72 weeks reported nausea in 28%, diarrhea in 23%, vomiting in 13% and constipation in 11%, against 8%, 8%, 2% and 5% with placebo [1]. In that trial program, 6.7% of adults on 15 mg stopped treatment because of adverse reactions, against 3.4% on placebo [1]. Rates from different trials and populations are not directly comparable [2].

What the labels flag as the dose goes up

Labeling across current GLP-1 products, including Wegovy and Foundayo, warns about acute pancreatitis (stop if suspected), severe gastrointestinal reactions (the drugs are not recommended in severe gastroparesis), acute kidney injury from volume depletion, acute gallbladder disease, hypoglycemia when combined with insulin or a sulfonylurea, serious hypersensitivity, diabetic retinopathy complications in type 2 diabetes, and pulmonary aspiration during general anesthesia or deep sedation [2][3]. The Zepbound label also says to discontinue if pancreatitis is suspected, and that patients with hypersensitivity reactions should promptly seek medical attention and discontinue [1].

The Wegovy and Foundayo labels warn that hypoglycemia risk rises when the drug is combined with insulin or a sulfonylurea, and they advise considering a lower dose of the insulin or sulfonylurea at the start [2][3].

Two labels tie contraception advice to each dose increase. The tirzepatide label advises switching to a non-oral contraceptive method or adding a barrier method for 4 weeks after starting and after each dose increase; the Foundayo label says 30 days [1][3]. Semaglutide labels carry no such advice [2].

What happens when treatment stops

STEP 4 tested stopping semaglutide, not tirzepatide. It enrolled adults with obesity or overweight and no diabetes. After a 20-week run-in, 803 adults who reached 2.4 mg semaglutide weekly were randomly assigned to continue the drug or switch to placebo for 48 weeks, with lifestyle intervention in both groups. The continued group lost another 7.9% of body weight; the placebo group gained 6.9%, a 14.8-point difference [4]. That trial tested a switch to placebo, not a step-down through lower doses.

Pregnancy is a labeled stopping point for weight-management treatment when pregnancy is recognized [2][3][1]. The Zepbound label advises discontinuing treatment when pregnancy is recognized [1], and the Wegovy label adds that treatment should be discontinued at least 2 months before a planned pregnancy because of the long half-life of semaglutide [2].

Before surgery or sedation

The Wegovy and Foundayo labels say pulmonary aspiration during general anesthesia or deep sedation has been reported in patients receiving GLP-1 receptor agonists, and instruct patients to inform their healthcare providers of any planned surgeries or procedures [2][3].

Can tirzepatide be combined with another GLP-1 drug?

The Wegovy, Saxenda, Zepbound and Foundayo labels all state that concomitant use with another GLP-1 receptor agonist is not recommended [2][6][1][3].