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Drug companion protocol

Tirzepatide (Zepbound)

Prescription only
GLP-1 / GIP dual receptor agonist

Also known as: Zepbound

A dual GLP-1 / GIP receptor agonist approved for chronic weight management.

Quickstart Highlights

Drug class
GLP-1 / GIP dual receptor agonist
Route
Subcutaneous injection
Schedule
Weekly subcutaneous injection
Evidence score
88

Quickstart highlights

  • ๐Ÿ’‰Subcutaneous injection
  • ๐Ÿ”ฌGLP-1 / GIP dual receptor agonist
  • ๐Ÿ–Š๏ธPre-filled autoinjector pen
  • ๐Ÿ“‹Prescription required

How this works

Mechanism of action and pharmacokinetic profile from published data.

Tirzepatide is a dual agonist at both the GLP-1 (glucagon-like peptide-1) and GIP (glucose-dependent insulinotropic polypeptide) receptors. GIP is the other major incretin hormone; activating it alongside GLP-1 appears to produce additive effects on appetite suppression, energy expenditure, and fat metabolism. In clinical trials, tirzepatide has produced larger weight reductions than any previously approved single-receptor GLP-1 agonist. The 10 mg and 15 mg doses used in Zepbound are approved for chronic weight management.

Time to peak (Tmax)
8โ€“72 hours after a subcutaneous injection.
Clearance
Degraded via proteolytic pathways; renal and hepatic dose adjustments are not required for mild-to-moderate impairment.
Elimination half-life
Approximately 5 days, supporting once-weekly subcutaneous dosing.
Bioavailability
~80% bioavailability after subcutaneous injection. Highly bound to albumin, which contributes to the long half-life.

Injection guide

Supplies, step-by-step technique, safety notes, and AU sharps disposal.

Supplies needed

  • โ—ฆYour prescribed Mounjaro/Zepbound autoinjector pen (correct dose) โ€” Each pen is single-use and contains a fixed dose (2.5, 5, 7.5, 10, 12.5, or 15 mg). Check the dose label matches your prescriber's instructions.
  • โ—ฆAlcohol swab
  • โ—ฆSharps disposal container

Step-by-step

  1. 1Wash your hands thoroughly
  2. 2Remove the pen from the fridge 30 minutes before use

    Room-temperature injection is more comfortable. Do not warm the pen in a microwave or hot water.

  3. 3Check the pen

    Look through the inspection window โ€” the liquid should be clear and colourless. Check the expiry date on the label. Do not use if cloudy, discoloured, or if particles are present.

  4. 4Peel off the base cap label and remove the base cap

    Pull the base cap straight off and discard โ€” do not twist. You will see the needle inside.

  5. 5Choose and clean your injection site

    Abdomen (5 cm from navel), upper thigh, or upper arm. Rotate sites each week. Wipe with an alcohol swab and let dry completely.

  6. 6Place the pen flat against your skin

    Hold the pen so the clear base is flush against the injection site at 90ยฐ. Do not angle it.

  7. 7Press the button and hold

    Press the injection button firmly. You will hear two clicks: the first click signals the injection has started; hold until the second click, then hold for an additional 5 seconds. The yellow indicator in the inspection window confirms the full dose was delivered.

  8. 8Lift the pen straight away from the skin

    The needle retracts automatically โ€” you will not see the needle after use.

  9. 9Dispose of the entire pen in your sharps container

    This is a single-use pen โ€” the entire pen goes into the sharps container after one injection.

Important notes

  • !Never inject into a vein or muscle
  • !This pen is single-use only โ€” discard after one injection

    Unlike some pens, Mounjaro and Zepbound pens are not multi-dose. Attempting to re-use will not deliver a full dose.

  • !Rotate injection sites each week
  • !Do not inject into scar tissue, bruises, or broken skin
  • !If you miss a dose by more than 4 days (Mounjaro) or 5 days (Zepbound), skip and resume on your next scheduled day
  • !Tell all healthcare providers you are using this medicine

    Slowed gastric emptying is relevant for surgical preparation and oral medicine absorption.

Sharps disposal

  • โ—ฆPlace the entire used pen in a sharps container โ€” The auto-retracted needle is still sharp inside the pen. The full pen must go into the sharps container โ€” not general waste.
  • โ—ฆNestSafe sharps mail-back (Australia) โ€” free kit from participating pharmacies
  • โ—ฆEnviroSafe mail-back (Australia)
  • โ—ฆCommunity pharmacy drop-off

Clinical Benefits & Side Effects

Observed outcomes, adverse effects, and lifecycle considerations from published trial data.

Benefits

Week 0

Starting Zepbound

Zepbound begins at 2.5 mg weekly for 4 weeks โ€” a tolerability step, not the therapeutic dose. Most people do not notice significant appetite suppression at this dose.

Week 1

First injection โ€” welcome to the journey

You've taken your first dose โ€” well done. This week is all about getting comfortable with the injection process and paying attention to how your body responds. Mild nausea, fatigue, or a reduced appetite may start to appear, but many people feel little change at all in week one.

Week 2

Body begins adjusting to the medication

Side effects like nausea, bloating, or loose stools may become more noticeable this week as your body continues to adjust. These feelings are usually temporary and tend to be most intense in the first few weeks. Eating smaller meals and staying well hydrated can make a real difference.

Week 3

Navigating early side effects

Week three can feel like the toughest stretch for some people โ€” nausea and food aversions may still be present. You may not see any change on the scales yet, and that is completely normal at this early stage. Focus on building small, sustainable habits rather than looking for dramatic results.

Week 4

Completing your first month โ€” stay the course

You've completed your first month on tirzepatide โ€” a genuine milestone. Side effects often begin to ease around this point, though they can still come and go. Some people notice a small shift in appetite or weight, but others won't yet โ€” both experiences are valid and expected.

Week 4

First dose escalation to 5 mg

The dose increases to 5 mg at week 5, held for 4 weeks. Nausea or mild GI effects may appear around escalation steps โ€” they usually settle within 1โ€“2 weeks.

Week 5

Dose escalation begins โ€” a new phase

If your prescriber has increased your dose, you may notice side effects returning or intensifying briefly as your body adapts to the higher level โ€” follow your prescriber's instructions on how to manage this step up. Appetite suppression often becomes more noticeable around this time, which may make eating enough protein a conscious effort.

Week 6

Appetite suppression becoming more noticeable

Many people find their hunger feels genuinely different this week โ€” food may be less appealing, portions may feel like too much, and the urge to snack can reduce significantly. This is the medication working, but be mindful to still eat regular, nourishing meals so your body gets adequate fuel and protein.

Side effects

โ—ฆAlopecia (hair thinning)(mild)

Reported in weight-loss trials; believed to be related to rapid weight loss rather than the drug itself

โ—ฆNausea(mild-to-moderate)

~35% at 15 mg; most common during dose escalation

โ—ฆDyspepsia(mild)

Reported; dose-related

โ—ฆConstipation(mild)

~25%

โ—ฆDecreased appetite(mild)

Frequently reported โ€” often the intended effect

โ—ฆInjection-site reaction(mild)

Mild; generally transient

โ—ฆDiarrhoea(mild-to-moderate)

~30%

โ—ฆVomiting(mild-to-moderate)

~25%

โ—ฆIncreased heart rate(mild)

Small average increase across dose arms

โ—ฆAbdominal pain(mild)

~20%

Lifecycle factors

GI side effects peak during dose escalation

In SURMOUNT-1, discontinuation due to GI events was ~4โ€“7%. Most GI adverse events were mild-to-moderate and resolved. If nausea or vomiting is severe or lasts more than a few days at a new dose, contact your prescriber โ€” a dose hold is preferable to discontinuation.

Tell every healthcare provider you are using Zepbound

Delayed gastric emptying affects preparation for surgical procedures, anaesthesia, and the timing of some medications. Always declare it before any procedure, even a dental extraction.

Manage nausea with cool, bland, and small

On days when nausea is at its worst, the three words to remember are: **cool, bland, and small**. Cool or room-temperature foods (like crackers, plain rice, banana, or a small bowl of oats) are often better tolerated than hot, rich, or strongly flavoured meals. Eating in a calm, upright position and waiting 20โ€“30 minutes before lying down can also help significantly.

Important note

This content is intended for therapeutic educational purposes only and does not constitute medical advice, diagnosis, or treatment. All information presented is based on published clinical trial data. Always follow your prescriber's instructions.

Nutrition & practical guidance

Food, hydration, and adherence tips compiled from trial data and clinical companion content.

Food and hydration

โœ… Prefer

Lean protein โ€” chicken breast, canned tuna, eggs, low-fat Greek yoghurtLean protein at every mealNon-starchy vegetables โ€” leafy greens, zucchini, broccoli, cucumber, capsicumHigh-fibre vegetablesPlain, easy-to-digest wholegrains โ€” rolled oats, brown rice, wholegrain toastLegumes โ€” lentils, chickpeas, cannellini beansSlow-digesting carbohydratesSmall, frequent mealsSoft fruits โ€” banana, melon, tinned peaches in juice, stewed apple

โš ๏ธ Limit

High-fat or fried foods โ€” chips, takeaway fried chicken, pastriesFried and very fatty foodsAdded sugar and sweet snacks โ€” biscuits, lollies, flavoured yoghurts, soft drinks

Adherence tips

administration

Rotate your injection sites consistently

Tirzepatide is injected subcutaneously โ€” into the fatty tissue of your abdomen, thigh, or upper arm. **Rotate your injection site each week** to prevent skin irritation or lumps from building up in one spot. Keep a simple note or pattern (e.g., left abdomen โ†’ right abdomen โ†’ thigh) so you always know where you injected last. Follow your prescriber's instructions on technique if you're unsure.

administration

Let the pen reach room temperature before injecting

Injecting medication that is straight from the fridge can sting more and feel uncomfortable. Remove your pen from the fridge **15โ€“30 minutes before your scheduled injection time** and let it come to room temperature. Do not warm it under hot water or in a microwave โ€” simply leaving it out is sufficient.

administration

The escalation schedule exists for a reason

Tirzepatide has six dose steps before reaching 15 mg. Each step is held for 4 weeks to let your GI system adapt. Skipping steps significantly increases nausea and vomiting risk. Your prescriber may keep you at a lower dose if it achieves your goals โ€” higher is not automatically better.

timing

Pick an injection day and stick to it

Tirzepatide is a **once-weekly injection**, so choosing a consistent day โ€” such as Sunday morning or Wednesday evening โ€” makes it much easier to remember and build into your routine. Setting a recurring phone reminder can help. Follow your prescriber's instructions if you ever need to adjust the timing of a dose.

nutrition

Protein targets matter more as weight loss accelerates

SURMOUNT-1 participants losing 20%+ of body weight were also losing lean mass. Aim for 1.2โ€“1.6 g protein per kg body weight daily. If appetite is very low, protein supplements (shakes, Greek yoghurt, cottage cheese) help hit the target without large portions.

timing

Consider injecting in the evening to sleep through side effects

Many people find that injecting **before bed** means that the peak of any nausea or fatigue happens overnight while they're asleep, making the next day easier to manage. This is a personal preference โ€” experiment to find what works best for your body and lifestyle.

hydration

Start every morning with a full glass of water

Before coffee, before breakfast โ€” make **250โ€“300 mL of still water** the very first thing you drink each day. This jumpstarts your hydration, supports digestion, and helps counteract the tendency to forget fluids when appetite and thirst cues are suppressed. Keep a full glass on your bedside table the night before as a visual reminder.

timing

Inject on the same day each week

If you need to change your injection day, take the dose on the new day and continue from there โ€” as long as the gap between doses is at least 3 days. Do not double-dose.

mindset

Weight loss may continue slowly past the expected plateau

SURMOUNT trial data showed weight loss curves that had not fully flattened by 72 weeks at the highest doses. Sustained treatment produced continued, slower reduction for many participants.

hydration

Sip fluids steadily โ€” don't gulp large amounts with meals

Drinking large volumes of fluid during a meal can contribute to bloating and nausea, especially in the early weeks. Instead, **sip water or herbal tea slowly throughout the day** and take small sips with meals rather than drinking a full glass all at once. A 500 mL reusable water bottle carried with you is a practical way to stay on track.

nutrition

Eat protein first at every meal

When appetite is suppressed, it's easy to fill up on carbohydrates or skip meals altogether โ€” both of which can reduce protein intake to an unhelpful level. Make it a habit to **eat your protein source first** at every meal โ€” whether that's eggs, chicken, fish, legumes, or Greek yoghurt. This helps protect muscle mass and keeps you fuller for longer on smaller portions.

nutrition

Don't skip meals โ€” eat small portions on a schedule

Reduced hunger is a feature of tirzepatide, but skipping meals entirely can lead to fatigue, muscle loss, and rebound overeating later. Aim for **3 small, structured meals per day** โ€” even if portions feel tiny. Set a reminder if needed. Think of it as fuelling your body with intention, not eating by hunger alone.

exercise

Start with gentle movement, not intense exercise

In the early weeks, your body is adjusting and energy levels may be lower than usual โ€” this is not the time to launch into a demanding gym program. Start with **20โ€“30 minute walks** a few times per week, which support weight management, improve mood, and are easy to sustain. Gradually build intensity as you feel more settled, and aim for at least 150 minutes of moderate activity per week over time.

exercise

Include resistance exercise to protect muscle

Weight loss on tirzepatide can include some muscle loss alongside fat loss if resistance exercise isn't part of your routine. **Bodyweight exercises, resistance bands, or light weights** 2โ€“3 times per week can help preserve and build muscle. Even simple exercises at home โ€” squats, wall push-ups, lunges โ€” make a meaningful difference over time.

sleep

Prioritise 7โ€“9 hours of sleep each night

Poor sleep can increase hunger hormones, reduce motivation, and impair the body's ability to manage weight effectively โ€” even while on medication. Aim for **7โ€“9 hours** of consistent, quality sleep by keeping a regular bedtime, limiting screen time in the hour before bed, and keeping your bedroom cool and dark. Sleep is one of the most underrated tools in your toolkit.

mindset

Track non-scale victories, not just your weight

The number on the scale is just one measure of progress โ€” and it can fluctuate daily based on fluid, food, and other factors. Keep a simple journal or notes app entry each week to record **non-scale victories**: how your clothes fit, your energy levels, how many flights of stairs you can climb, your sleep quality, or how your relationship with food is shifting. These changes are real and meaningful.

mindset

Prepare for the early weeks to be challenging

It's important to be honest with yourself: **the first four to six weeks can be hard**. Nausea, fatigue, and the absence of visible results can make it tempting to feel discouraged. Having realistic expectations from the start โ€” and reminding yourself that these early weeks are temporary โ€” can make a significant difference to how you feel emotionally. Connecting with a supportive community or speaking to your prescriber when things feel tough is always a good idea.

Safety and interactions

Share this information with your prescriber for personalised care decisions.

Who should not take this

Zepbound is a prescription medicine. Do not use if you have: โ€ข A personal or family history of medullary thyroid carcinoma (MTC) โ€ข Multiple endocrine neoplasia syndrome type 2 (MEN2) โ€ข A known allergy or hypersensitivity to tirzepatide or any ingredient in the product Use with caution (discuss with your prescriber) if you have: โ€ข A history of pancreatitis โ€ข Diabetic retinopathy โ€ข Severe kidney or liver disease โ€ข Active or recent eating disorder Not recommended during pregnancy or breastfeeding. Always disclose your full medical history to your prescriber.

Known interactions

  • Insulin and insulin secretagogues (e.g. sulfonylureas)
    significant

    Increased hypoglycaemia risk. Prescribers typically reduce insulin or sulfonylurea doses when starting tirzepatide.

  • Oral contraceptives
    moderate

    Delayed gastric emptying may reduce oral contraceptive absorption around dose escalation. Consider additional non-hormonal contraception.

  • Medicines with a narrow therapeutic index (warfarin, anti-epileptics, ciclosporin)
    moderate

    Altered gastric emptying can change drug absorption. Additional monitoring may be warranted.

  • Alcohol
    moderate

    Worsens nausea and dehydration; increases hypoglycaemia risk when combined with insulin or sulfonylureas.

Storage and handling

Store the Zepbound pen in the refrigerator at 2โ€“8ยฐC (36โ€“46ยฐF). โ€ข After removal from the fridge: use within 21 days, keeping below 30ยฐC. โ€ข Do not freeze โ€” freezing destroys the active molecule. โ€ข Store in the original carton to protect from light. โ€ข Do not use if the liquid looks cloudy or discoloured.

Research evidence

Published studies connected to this peptide with dosage and outcomes context.

Randomized Trial of Tirzepatide after Intensive Lifestyle Intervention (SURMOUNT-3)

Human trial ยท 2023 ยท Nature Medicine ยท n=806 ยท Adults with obesity or overweight plus comorbidity, without type 2 diabetes; after 12-week intensive lifestyle run-in

806 adults who had completed a 12-week intensive lifestyle intervention were randomised to tirzepatide 15 mg weekly or placebo for 72 weeks. Mean total weight loss from before the lifestyle run-in was โˆ’26.6% with tirzepatide versus โˆ’3.8% with placebo, demonstrating additive effects of combining intensive lifestyle support with pharmacotherapy.

Reported outcomes

  • weight_loss: Intensive lifestyle intervention prior to starting tirzepatide amplified total weight loss beyond pharmacotherapy alone. (Secondary)
  • weight_loss: Total mean body-weight loss of 26.6% from pre-run-in baseline with tirzepatide 15 mg at 72 weeks, versus 3.8% with placebo. (Primary outcome)
DOI: 10.1038/s41591-023-02597-w โ†—

Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1)

Human trial ยท 2022 ยท New England Journal of Medicine ยท n=2539 ยท Adults with obesity (BMI โ‰ฅ30) or overweight (BMI โ‰ฅ27) with โ‰ฅ1 weight-related condition, without type 2 diabetes

2,539 adults were randomised to tirzepatide 5, 10, or 15 mg once weekly or placebo for 72 weeks. Mean body-weight change was โˆ’15.0%, โˆ’19.5%, and โˆ’20.9% at 5, 10, and 15 mg respectively, versus โˆ’3.1% for placebo. More than 89% of participants on 15 mg achieved โ‰ฅ5% weight loss. Adverse events were predominantly mild-to-moderate GI events.

Reported outcomes

  • responder_rate: More than 89% of participants on 15 mg achieved โ‰ฅ5% weight loss; 56% achieved โ‰ฅ20%. (Secondary)
  • weight_loss: Mean body-weight reductions of 15.0%, 19.5%, and 20.9% at 5, 10, and 15 mg respectively at 72 weeks, versus 3.1% with placebo. (Primary outcome)
  • cardiometabolic: Improvements in waist circumference, blood pressure, lipids, and fasting glucose observed across all dose arms. (Secondary)

Reported dosage

  • 5 mg ยท once weekly subcutaneous ยท 72 weeks โ€” 5 mg maintenance arm โ€” or escalation step 2 for higher arms.
  • 10 mg ยท once weekly subcutaneous ยท 72 weeks โ€” 10 mg maintenance arm.
  • 2.5 mg ยท once weekly subcutaneous ยท 72 weeks โ€” Starting dose for all arms; held 4 weeks as tolerability run-in.
  • 15 mg ยท once weekly subcutaneous ยท 72 weeks โ€” Highest dose arm in SURMOUNT-1; reached via 2.5โ†’5โ†’7.5โ†’10โ†’12.5โ†’15 mg escalation.
DOI: 10.1056/NEJMoa2206038 โ†—

Tirzepatide versus Semaglutide Once Weekly in Patients with Type 2 Diabetes (SURPASS-2)

Human trial ยท 2021 ยท New England Journal of Medicine ยท n=1879 ยท Adults with type 2 diabetes inadequately controlled on metformin

1,879 adults with type 2 diabetes on metformin were randomised to tirzepatide 5, 10, or 15 mg weekly or semaglutide 1 mg weekly for 40 weeks. HbA1c reductions were โˆ’2.01%, โˆ’2.24%, and โˆ’2.30% for tirzepatide versus โˆ’1.86% for semaglutide 1 mg. Body-weight reductions were โˆ’7.6, โˆ’9.3, and โˆ’11.2 kg versus โˆ’5.7 kg. All tirzepatide doses were non-inferior; 10 mg and 15 mg were superior to semaglutide.

DOI: 10.1056/NEJMoa2107519 โ†—

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