Octreotide is a synthetic medication that mirrors the actions of somatostatin, a natural hormone. Its primary application in emergency medicine is to manage specific kinds of severe upper gastrointestinal (GI) bleeding. The drug is administered to patients to control active bleeding and improve stability before more definitive medical procedures can be performed.
Octreotide’s Mechanism of Action
Octreotide’s principal effect in treating a GI bleed is the reduction of blood flow to the digestive system. This area, known as the splanchnic circulation, experiences decreased blood supply because octreotide inhibits the release of hormones like glucagon that cause blood vessels to widen. By preventing this vasodilation, the medication constricts the blood vessels feeding the gut.
This targeted vasoconstriction is impactful on the portal venous system, which carries blood from the gastrointestinal tract to the liver. In medical conditions where the pressure within this system becomes dangerously high, octreotide addresses this by lowering the volume of blood entering the portal vein, which reduces the pressure within it.
The medication also enhances the aggregation of platelets, which are cell fragments that form clots to stop bleeding. Additionally, octreotide suppresses the secretion of gastric acid and pepsin, substances in the stomach that can interfere with clot formation and worsen bleeding from certain lesions.
Primary Use in Variceal Bleeding
The main application for octreotide is managing variceal bleeding, a life-threatening complication of advanced liver disease, or cirrhosis. Varices are abnormally enlarged veins that develop, most commonly, in the esophagus and stomach. They form as a direct result of elevated pressure in the portal vein system, a condition known as portal hypertension.
When liver function is compromised, blood cannot flow through it properly, causing it to back up and engorge these fragile vessels. These swollen veins have thin walls and are prone to rupture, which can lead to massive and rapid blood loss. Octreotide is a first-line medication for this emergency because its mechanism directly counteracts the underlying problem of portal hypertension.
It is initiated as soon as a variceal bleed is suspected, often before a diagnosis is confirmed via an endoscopic procedure. While its effectiveness in treating variceal hemorrhage is well-established, its use for other types of upper GI bleeds, such as those from peptic ulcers, is less routine. For non-variceal bleeding, other treatments like proton pump inhibitors are preferred.
Administration and Dosage Protocol
In a hospital setting, octreotide is administered intravenously (IV) for a rapid onset of action. The treatment protocol begins with an initial, larger dose known as an IV bolus. This bolus, 50 micrograms, is given to quickly raise the drug’s concentration in the blood, allowing its effects on blood flow and portal pressure to begin almost immediately.
Following the initial bolus, a continuous IV infusion is started to maintain a steady level of the medication in the body. The infusion rate is 50 micrograms per hour, providing a consistent effect to control the hemorrhage and reduce the risk of re-bleeding.
This treatment is maintained for two to five days, acting as a bridge to a more definitive treatment. An endoscopic procedure is a common next step, where a physician can directly visualize the varices and perform procedures like band ligation to stop the bleeding source.
Potential Side Effects and Monitoring
While octreotide is administered, patients are monitored for potential side effects. The most frequent adverse effects are gastrointestinal and are related to the drug’s influence on digestive secretions and motility. These include:
- Abdominal cramping
- Nausea
- Vomiting
- Diarrhea
Another complication is the formation of gallstones or biliary sludge with prolonged use, as the medication can inhibit gallbladder contractions.
A notable effect of octreotide is its impact on blood sugar regulation. The drug can alter the balance between insulin and glucagon, which can lead to either elevated blood sugar (hyperglycemia) or low blood sugar (hypoglycemia). Therefore, healthcare providers closely monitor a patient’s blood glucose levels throughout the infusion.
Other less common side effects can involve changes in heart function, such as a slowed heart rate (bradycardia), other rhythm disturbances, and pain at the injection site.