Dulaglutide

Introduction Overview

Generic Name

dulaglutide

Brand Name

Trulicity

Dosage Form

injection, solution

Drug Class

GLP-1 Agonists (Incretin Mimetics)

Pharmacokinetics

Absorption:
Dulaglutide administered subcutaneously demonstrates an absolute bioavailability ranging between 47% to 65% depending on the dose - 65% for 0.75 mg and 47% for 1.5 mg dosages. Its absorption is gradual with the time to maximal plasma concentration (Tmax) at steady state ranging from 24 to 72 hours (median approximately 48 hours). Dulaglutide concentrations increase proportionally with dose escalation from 0.75 mg to 4.5 mg. The bioavailability is characterized by slow and sustained absorption suitable for once-weekly dosing. Absorption is consistent regardless of injection site (abdomen, thigh, or upper arm).

Distribution:
The apparent central volume of distribution averages 3.09 liters, with a peripheral volume of distribution approximately 5.98 liters, indicating limited distribution primarily confined to plasma and interstitial fluid. Dulaglutide is a large molecule fusion protein (approximately 63 kDa) that does not extensively distribute into tissues. The pharmacokinetics are consistent among healthy subjects and type 2 diabetes patients, with population pharmacokinetic analyses confirming no clinically relevant effect of age, gender, race, body weight, or renal and hepatic impairment on distribution.

Metabolism:
Dulaglutide is a recombinant fusion protein and undergoes metabolism via proteolytic degradation to its constituent amino acids through general protein catabolism pathways. Unlike small molecule drugs, it is not metabolized by hepatic cytochrome P450 enzymes, and no specific metabolic enzymes have been identified. This catabolic route accounts for its degradation and clearance without involvement of liver metabolizing enzymes, minimizing potential for drug-drug interactions via metabolic pathways.

Elimination:
The total systemic clearance of dulaglutide averages 0.142 L/h, with an elimination half-life of approximately 5 days, supporting its once-weekly dosing regimen. Due to its size and metabolism, renal or hepatic elimination plays a minimal direct role. Pharmacokinetic studies in patients with varying degrees of renal impairment, including end-stage renal disease, show modest increases in systemic exposure (up to 28% in moderate impairment) but not clinically significant enough to mandate dosage adjustment. Similarly, hepatic impairment results in slight decreases in exposure but is clinically insignificant. Steady-state concentrations are typically reached within 2 to 4 weeks of weekly dosing.

Dosage Forms

Available Dosage Forms:
Trulicity is supplied as a clear, colorless, sterile, preservative-free solution in single-dose prefilled pens designed for subcutaneous injection. Available strengths include:
- 0.75 mg/0.5 mL solution in single-dose pen
- 1.5 mg/0.5 mL solution in single-dose pen
- 3 mg/0.5 mL solution in single-dose pen
- 4.5 mg/0.5 mL solution in single-dose pen

Dosages for Adults and Adolescents:
- Initial adult and pediatric dose (≥10 years): 0.75 mg injected subcutaneously once weekly.
- Dose may be escalated after a minimum of 4 weeks based on glycemic response and tolerability: to 1.5 mg once weekly, then further in 1.5 mg increments (3 mg, then maximum 4.5 mg once weekly).
- Pediatric patients (≥10 years) can be maintained up to 1.5 mg once weekly.
- Maximum recommended dose for adults is 4.5 mg once weekly.
- Dose adjustments should be individualized considering efficacy and gastrointestinal tolerability.

Specific Patient Populations:
- No dosage adjustment is required for renal impairment including ESRD or hepatic impairment based on pharmacokinetic data.
- Geriatric patients (≥65 years) show no clinically significant PK differences; no dose modification is required.
- Pediatric patients (≥10 years) are recommended starting at 0.75 mg weekly; safety and efficacy have not been established in <10 years.

Administration Instructions:
- Administer via subcutaneous injection in the abdomen, thigh, or upper arm.
- Injection site rotation is recommended with each dose.
- Can be administered irrespective of meals and time of day.
- If a dose is missed and there are at least 3 days before the next scheduled dose, dose should be administered as soon as possible.
- If less than 3 days remain before next dose, skip missed dose and administer next dose on schedule.

Mechanism Of Action

Trulicity (dulaglutide) is a glucagon-like peptide-1 (GLP-1) receptor agonist that mimics the incretin hormone GLP-1, a key regulator of glucose homeostasis. Dulaglutide exhibits approximately 90% amino acid sequence homology to native human GLP-1 (7-37) and selectively binds to and activates GLP-1 receptors located on pancreatic beta cells.

Activation of GLP-1 receptors by dulaglutide stimulates the intracellular production of cyclic AMP (cAMP), which enhances glucose-dependent insulin secretion. This results in increased insulin release only when blood glucose levels are elevated, thereby reducing the risk of hypoglycemia. Concurrently, dulaglutide suppresses glucagon secretion from alpha cells in a glucose-dependent manner, further reducing hepatic glucose production.

Importantly, dulaglutide also slows gastric emptying by modulating gastrointestinal motility, which contributes to a reduction in postprandial glucose excursions. This slowing of gastric emptying is dose-dependent and most pronounced after the initial dose, diminishing with chronic administration.

At the molecular level, dulaglutide's design as a fusion protein linked to an Fc fragment of human IgG4 extends its half-life by reducing renal clearance and protecting against rapid degradation by dipeptidyl peptidase-4 (DPP-4). This pharmacokinetic optimization enables sustained receptor activation permitting once-weekly dosing.

Clinically, the drug improves glycemic control by restoring deficient insulin secretion, suppressing inappropriate glucagon release, and reducing post-meal glucose spikes, leading to reductions in hemoglobin A1c, fasting, and postprandial glucose levels. Compared to native GLP-1 or short-acting agonists, dulaglutide provides prolonged receptor engagement and more consistent glucose lowering.

Extensive clinical data corroborate dulaglutide's efficacy and safety profile; however, animal studies have demonstrated potential risk of thyroid C-cell neoplasms, warranting careful monitoring and contraindications in patients predisposed to medullary thyroid carcinoma (MTC).

Pharmacological Actions

Acts as a selective agonist at the GLP-1 receptor, enhancing glucose-dependent insulin secretion.
Suppresses inappropriate postprandial glucagon secretion to decrease hepatic glucose output.
Delays gastric emptying, resulting in reduced postprandial glucose excursions.
Promotes beta cell function and may improve glucose sensitivity via cAMP-mediated pathways.
Exhibits a prolonged half-life enabling sustained receptor activation suitable for once-weekly dosing.
Lowers fasting and postprandial blood glucose levels in patients with type 2 diabetes mellitus.
Reduces hemoglobin A1c levels effectively as monotherapy or in combination with other antidiabetic agents.
Associated with modest weight reduction, possibly due to reduced appetite and caloric intake.
Improves cardiovascular outcomes by reducing major adverse cardiovascular events in at-risk populations.
Does not induce hypoglycemia when used as monotherapy due to glucose-dependent mechanism.
Triggers potential immunogenic responses but low incidence of anti-drug antibodies with minimal clinical impact.
Produces gastrointestinal side effects primarily due to delayed gastric motility.
Alters cardiac electrophysiology modestly with slight increase in heart rate and PR interval.
Minimal metabolism through hepatic enzymes, being degraded via general protein catabolism.
Demonstrates potential thyroid C-cell tumorigenesis in rodent species, with uncertain human relevance.

Therapeutic Or Clinical Uses

Adjunct treatment to diet and exercise for glycemic control in adults with type 2 diabetes mellitus.
Improvement of glycemic control in pediatric patients aged 10 years and older with type 2 diabetes.
Reduction of major adverse cardiovascular events (including cardiovascular death, non-fatal myocardial infarction, and non-fatal stroke) in adults with type 2 diabetes and established cardiovascular disease or multiple cardiovascular risk factors.
Monotherapy or combination therapy with oral antidiabetics such as metformin, sulfonylureas, or insulin.
Treatment option for patients with moderate to severe renal impairment given its stable pharmacokinetics.
Add-on therapy to basal insulin regimens to enhance glycemic efficacy and reduce insulin dose requirements.
Used as add-on to sodium-glucose co-transporter 2 inhibitors (SGLT2i) with or without metformin.
Management of type 2 diabetes mellitus requiring weekly dosing for improved adherence.
Potentially beneficial for patients with cardiovascular risk factors due to demonstrated cardiovascular benefit.
Therapy that may induce modest weight loss contributing to metabolic improvements.
For patients intolerant to or inadequate responders to other GLP-1 receptor agonists or oral agents.
Improves both fasting and postprandial glucose control, addressing multiple aspects of hyperglycemia.

Side Or Adverse Effects

Nausea, often mild to moderate and dose-dependent, occurring in up to 21% of patients.
Diarrhea with incidence up to 13%, typically transient during treatment initiation.
Vomiting, reported in 6%-13% of patients, typically resolving with continued therapy.
Abdominal pain or discomfort including upper and lower abdominal pain.
Decreased appetite leading to weight loss in some patients.
Dyspepsia and gastrointestinal reflux disease symptoms.
Fatigue and malaise reported less commonly than gastrointestinal symptoms.
Hypoglycemia, particularly when used with insulin secretagogues or insulin; severe cases are rare.
Serious hypersensitivity reactions including anaphylaxis and angioedema.
Acute pancreatitis, including fatal and necrotizing pancreatitis; discontinue if suspected.
Injection site reactions such as rash or erythema, generally mild and infrequent.
Acute kidney injury due to volume depletion, associated with dehydration from GI side effects.
Severe gastrointestinal side effects like gastroparesis are a contraindication for use.
Increased heart rate and sinus tachycardia reported, with PR interval prolongation on ECG.
Complications related to diabetic retinopathy in patients with pre-existing retinopathy.
Gallbladder disease including cholelithiasis and cholecystitis reported in some patients.
Pulmonary aspiration risk during general anesthesia or deep sedation due to delayed gastric emptying.

Precautions

Contraindicated in patients with personal or family history of medullary thyroid carcinoma (MTC) or Multiple Endocrine Neoplasia syndrome type 2 (MEN 2).
Monitor patients for symptoms suggestive of thyroid tumors: neck mass, dysphagia, hoarseness, or dyspnea.
Observe for signs of pancreatitis and discontinue therapy immediately if pancreatitis is suspected.
Use caution and monitor blood glucose carefully when co-administered with insulin secretagogues or insulin due to hypoglycemia risk.
Patients with severe gastrointestinal disease, especially gastroparesis, should not receive Trulicity.
Monitor renal function during treatment, especially in patients experiencing nausea, vomiting, or diarrhea.
Caution advised in patients with a history of pancreatitis or acute kidney injury.
Use with caution in hepatic impairment due to limited clinical data, although pharmacokinetics are not substantially altered.
Advise patients of potential for severe gastrointestinal adverse reactions and instruct to report persistent symptoms.
Patients with pre-existing diabetic retinopathy should be monitored for progression during therapy.
Exercise caution in elderly patients; no clinically significant differences observed but comorbidities considered.
Inform patients undergoing anesthesia or deep sedation about possible delayed gastric emptying and aspiration risk.
Educate patients on recognizing and managing hypoglycemia symptoms when on combination therapy.
Evaluate patients presenting with injection-site hypersensitivity reactions promptly.
Consider potential drug interactions affecting oral medication absorption and adjust dosing if necessary.

Warnings

Boxed Warning: Risk of thyroid C-cell tumors - dulaglutide causes thyroid C-cell tumors in rodents; human relevance is unknown.
Contraindicated in patients with personal or family history of medullary thyroid carcinoma (MTC) or MEN 2 syndrome.
Observe for acute pancreatitis; discontinue treatment immediately if pancreatitis is suspected.
Potential for severe gastrointestinal adverse reactions including nausea, vomiting, diarrhea, and gastroparesis.
Increased risk of hypoglycemia when used with insulin or insulin secretagogues; dose adjustment may be required.
Postmarketing reports of serious hypersensitivity reactions including anaphylaxis and angioedema; discontinue if these occur.
Risk of acute kidney injury due to dehydration from gastrointestinal adverse effects; monitor renal function.
Potential exacerbation of diabetic retinopathy complications in patients with pre-existing retinopathy.
Reports of gallbladder disease including cholelithiasis and cholecystitis; gallbladder studies indicated if suspected.
Risk of pulmonary aspiration during general anesthesia or deep sedation due to delayed gastric emptying.
Not recommended for patients with severe gastroparesis or severe gastrointestinal disease.
Use caution in patients undergoing surgery or procedures requiring anesthesia; instruct patients to inform providers.
Monitor for injection-site reactions and discontinue if severe hypersensitivity occurs.
Advise patients on appropriate dosing schedules and management of missed doses to avoid adverse effects.
Avoid use in pediatric patients under 10 years of age due to unestablished safety and efficacy.

Contraindication

Personal or family history of medullary thyroid carcinoma (MTC) or Multiple Endocrine Neoplasia syndrome type 2 (MEN 2).
Known serious hypersensitivity reactions to dulaglutide or any component of the formulation.
History of prior serious allergic reaction including anaphylaxis or angioedema to Trulicity.
Patients with severe gastroparesis or significant gastrointestinal disease.
Pediatric patients under 10 years of age due to lack of established safety and efficacy.
Concurrent use with other GLP-1 receptor agonists or medications with similar mechanisms without medical supervision.
Patients with known hypersensitivity to excipients such as polysorbate 80 or mannitol.
Use in patients with pancreatitis is contraindicated due to risk of exacerbation.
Use not recommended in patients with unstable or severe renal impairment without close monitoring.
Pregnant women unless potential benefits outweigh risks, as safety has not been established.
Patients with any condition where delayed gastric emptying poses a significant risk.

Drug Interactions

Oral medications may have reduced rate of absorption due to dulaglutide-induced delayed gastric emptying; monitor drugs with narrow therapeutic index such as warfarin.
Concomitant use with insulin secretagogues (e.g., sulfonylureas) or insulin increases risk of hypoglycemia; dose adjustments recommended.
No clinically significant pharmacokinetic interactions observed with sitagliptin or other commonly co-administered drugs.
Dulaglutide does not significantly alter cytochrome P450 enzyme activity, minimizing metabolic drug interactions.
Gastric emptying delay is dose-dependent and attenuates with dose escalation.
Limited experience with co-administration of 3 mg and 4.5 mg doses with other medications; caution advised.
No adjustment needed for concomitant use with metformin, thiazolidinediones, SGLT2 inhibitors, or insulin analogs.
Potential for gastrointestinal side effects may be increased with other agents causing nausea or vomiting.
Monitor glucose levels closely when initiating or discontinuing dulaglutide in patients on antidiabetic medications.
No known interactions impacting hormonal contraceptives or anticoagulants beyond absorption considerations.
No effect on absorption or pharmacokinetics of digoxin or atorvastatin noted in clinical pharmacology studies.
Patients on multiple medications should maintain a medication list and inform healthcare providers of dulaglutide use.
No contraindication for vaccination, but no specific studies have evaluated interactions.
Caution with drugs requiring precise timing and dosing due to altered gastrointestinal motility.
No significant interactions reported with common cardiovascular medications such as beta-blockers or ACE inhibitors.

Preparations Of The Drug

Pre-filled single-dose injection pens containing dulaglutide solution; designed for subcutaneous use.
Available in four dosage strengths: 0.75 mg/0.5 mL, 1.5 mg/0.5 mL, 3 mg/0.5 mL, and 4.5 mg/0.5 mL.
Clear, colorless, sterile, preservative-free solution formulated for once-weekly administration.
Excipients include citric acid anhydrous, mannitol, polysorbate 80, and trisodium citrate dihydrate in water for injection.
Supplied in cartons containing 4 pens each; pens intended for single use only.
The pen device includes locking mechanisms and clear indicators to ensure correct administration.
Storage requirements include refrigeration between 2°C to 8°C; may be kept at room temperature up to 14 days prior to use.
Protected from light and freezing; pens should not be used if frozen or if solution appears discolored or cloudy.
Comes with detailed patient Instructions for Use to ensure proper administration technique and disposal.
Disposal requires use of FDA-cleared sharps containers due to needle safety considerations.
Pens contain glass components requiring careful handling to avoid breakage.
Identifying labels with expiration date and dosage strength clearly marked on the pen.
Provided with comprehensive Medication Guide and patient counseling information.
Manufactured by Eli Lilly and Company, ensuring quality and consistency of the biologic formulation.