Linagliptin inhibits the enzyme DPP-4, which degrades incretin hormones such as glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP). By preventing their breakdown, linagliptin:

• Enhances Insulin Secretion: Increases glucose-dependent insulin release from pancreatic β-cells.
• Suppresses Glucagon: Reduces inappropriate glucagon secretion from α-cells, lowering hepatic glucose production.
• Slows Gastric Emptying: Mildly delays gastric emptying via GLP-1 activity, moderating postprandial glucose spikes (Lippincott).

Unlike other DPP-4 inhibitors, linagliptin has a non-renal route of excretion, making it unique in its pharmacokinetics (Lange).

1. Type 2 Diabetes Mellitus:
   • Monotherapy or combined with other agents (e.g., metformin, sulfonylureas, insulin) when diet/exercise alone are insufficient.
   • Preferred in patients with renal impairment due to no dose adjustment requirements (BNF).
2. Cardiovascular Safety:
   • Neutral effect on cardiovascular outcomes but safe in patients with heart disease (Lippincott).

• Standard Dose: 5 mg once daily, taken orally with or without food.
• Special Populations:
  • Renal Impairment: No dose adjustment required (unlike other DPP-4 inhibitors). Safe in all stages, including end-stage renal disease (BNF).
  • Hepatic Impairment: No adjustment needed.

Elderly: Safe without dose changes

• Nasopharyngitis, headache, upper respiratory infections.
• Hypoglycemia (when combined with sulfonylureas or insulin).

Serious (Rare):

• Pancreatitis: Monitor for severe abdominal pain.
• Hypersensitivity Reactions: Angioedema, rash, or anaphylaxis.
• Arthralgia: Severe joint pain reported in post-marketing data (BNF).

• Contraindications:
o Hypersensitivity to linagliptin or DPP-4 inhibitors.
o History of pancreatitis (relative contraindication).

• • Renal function (baseline and periodically).
  • HbA1c, blood glucose, and signs of pancreatitis.

• • Pregnancy: Category B; use only if benefits outweigh risks.
  • Lactation: Avoid—limited data on excretion in breast milk (Lange).

• Strong CYP3A4 Inducers (e.g., rifampicin): May reduce linagliptin efficacy.
• Insulin/Sulfonylureas: Increased hypoglycemia risk; consider dose reduction.
• ACE Inhibitors: Theoretical risk of angioedema (rare) (BNF).

• Generic: Linagliptin.
• Brand Name: Trajenta® (Boehringer Ingelheim).

Trajenta® is exclusively an oral tablet. There is no injectable form of linagliptin. Injectable diabetes medications include:

• GLP-1 Receptor Agonists: Semaglutide (Ozempic®), Dulaglutide (Trulicity®).
• Insulins: Insulin glargine (Lantus®), insulin aspart (NovoRapid®).