Octreotide LAR
Hormonal / ClinicalAlso known as: Sandostatin LAR, Mycapssa
Mechanism
A long-acting monthly injection form of octreotide — the workhorse somatostatin analog used for acromegaly and carcinoid tumors. The drug is trapped in tiny biodegradable microspheres that slowly release it over 4 weeks. Even more remarkable: Mycapssa is now the first oral somatostatin analog, using a special absorption enhancer to get the peptide through the stomach lining intact.
Technical detail
Long-acting depot formulation of octreotide (cyclic octapeptide somatostatin analog). Encapsulated in poly(D,L-lactide-co-glycolide) (PLGA) microspheres for sustained release via IM injection. Initial burst release (first day) → drug-free interval (days 2-7) → sustained release (day 7-42) as PLGA matrix degrades via hydrolysis. Dosing: 10mg, 20mg, or 30mg IM every 4 weeks. Mycapssa (oral octreotide capsules): uses Transient Permeability Enhancer (TPE) technology — sodium caprylate (C8 medium-chain fatty acid) transiently opens tight junctions in gastric epithelium, enabling paracellular octreotide absorption. Oral bioavailability ~0.5-1% (sufficient due to high dose: 20mg capsule delivers ~100-200 mcg effective). Taken BID on empty stomach. Both formulations activate SSTR2 and SSTR5 receptors, suppressing GH, glucagon, insulin, and various gut peptides. Also antiproliferative effects via SSTR2-mediated apoptosis and cell cycle arrest in neuroendocrine tumors.
Effects
ENDOCRINE SYSTEM (GH AXIS): Octreotide is a synthetic somatostatin analog (cyclic octapeptide) that binds somatostatin receptors (SSTR), particularly SSTR2 and SSTR5 [pharmacological]. LAR (Long-Acting Release) formulation uses biodegradable microspheres (poly-DL-lactide-co-glycolide) for sustained intramuscular release over 28 days [pharmacokinetic]. Suppresses GH secretion from pituitary adenomas — normalizes IGF-1 in approximately 55-65% of acromegaly patients on optimal doses [RCT, meta-analyses]. Tumor shrinkage: clinically significant adenoma volume reduction (>20%) in 60-75% of patients, with some achieving >50% reduction — this is a disease-modifying effect beyond hormone control [RCT — Caron et al., 2014]. GASTROINTESTINAL (NET): Potent inhibitor of GI hormone release — suppresses serotonin (carcinoid syndrome: diarrhea, flushing), VIP (VIPoma: watery diarrhea), glucagon (glucagonoma: necrolytic migratory erythema), gastrin (gastrinoma: peptic ulceration) [RCT]. Antiproliferative effect on neuroendocrine tumor cells via SSTR2-mediated cell cycle arrest and apoptosis — PROMID trial demonstrated prolonged time to tumor progression in midgut NETs (14.3 months vs. 6 months placebo) [RCT — Rinke et al., 2009]. HEPATOBILIARY: Inhibits cholecystokinin release and gallbladder contractility — gallstone/sludge formation in 15-30% of patients on long-term therapy [RCT, clinical]. Mechanism: bile stasis + altered bile salt composition. METABOLIC: Suppresses insulin secretion — can worsen glycemic control in diabetic patients or cause hyperglycemia [clinical]. Also suppresses glucagon, creating a complex net effect on glucose homeostasis. CARDIOVASCULAR: Mild bradycardia (sinus node suppression) in some patients [clinical]. ORAL FORMULATION (MYCAPSSA): Uses Transient Permeability Enhancer (TPE) technology — sodium caprylate transiently opens intestinal tight junctions, allowing octreotide absorption. Bioavailability remains low (~0.5-1%) but sufficient for therapeutic levels [RCT — OPTIMAL trial].
Practitioner Guide
ADMINISTRATION — LAR: Deep intramuscular injection (gluteal) every 28 days. CRITICAL TECHNIQUE: Must be injected into the gluteal muscle (not subcutaneous) — use 20-gauge, 1.5-inch needle. Allow the microsphere suspension to reach room temperature for 30-60 minutes before injection. Mix vigorously per instructions to ensure uniform microsphere suspension. Inject immediately after mixing — microspheres settle rapidly. Alternate left and right gluteal sites. DOSING — ACROMEGALY: Start at 20 mg IM q28days. Assess GH and IGF-1 at 3 months. If not controlled: increase to 30 mg q28days. If well-controlled for 3+ months: can reduce to 10 mg q28days. Target: IGF-1 within age/sex-normalized reference range, GH <1.0 ng/mL. DOSING — NET/CARCINOID: Start at 20 mg IM q28days. For uncontrolled symptoms: increase to 30 mg q28days. Can also give rescue subcutaneous octreotide 100-200 mcg SC q8h for breakthrough carcinoid crises (always have SC octreotide available for patients with carcinoid syndrome). ORAL MYCAPSSA: 20 mg twice daily on empty stomach (at least 1 hour before or 2 hours after food) with water. Fasting is essential — food reduces absorption. Switch from LAR to oral only after stable on LAR for ≥3 months with controlled biochemistry. GALLSTONE PREVENTION: Ursodeoxycholic acid (UDCA) 300 mg BID prophylactically for patients starting long-term octreotide — reduces gallstone incidence from ~25% to ~10%. Abdominal ultrasound at baseline and every 6-12 months. Educate patients on symptoms of cholecystitis/cholelithiasis. GLYCEMIC MONITORING: Check fasting glucose and HbA1c at baseline, 3 months, then every 6 months. Diabetic patients may need insulin dose adjustment (octreotide suppresses both insulin and glucagon — net effect variable). INJECTION SITE MANAGEMENT: Hard nodules at injection site are common with LAR (microsphere deposits) — rotate sites, massage gently post-injection. If intolerance develops, consider switching to lanreotide Autogel (SC deep, pre-filled syringe — easier administration). COST: LAR is expensive (~$3,000-5,000/month). Mycapssa oral similarly expensive. Generic immediate-release SC octreotide is much cheaper for rescue dosing. STORAGE: LAR kit refrigerated (2-8°C). Can be at room temperature for the day of injection. SC octreotide: room temperature stable for 14 days.
Research Summary
TIER 1: PROMID trial (Rinke et al., 2009) — landmark RCT: octreotide LAR 30 mg vs. placebo in midgut NETs, doubled time to tumor progression (14.3 vs. 6.0 months). Multiple acromegaly RCTs demonstrating IGF-1 normalization in 55-65%. OPTIMAL trial (Melmed et al., 2021) — pivotal RCT for oral Mycapssa, demonstrated non-inferior GH/IGF-1 control when switched from injectable somatostatin analogs. Caron et al., 2014 — primary medical therapy in acromegaly showing significant tumor shrinkage. FDA-approved: Sandostatin LAR (1998) for acromegaly and carcinoid syndrome; Mycapssa (2020) for acromegaly maintenance. TIER 2: Meta-analyses of somatostatin analogs in acromegaly (Defined et al., systematic Cochrane review). CLARINET trial (lanreotide, not octreotide — but validates the SSA class for NET antiproliferative effect). Reviews comparing octreotide vs. lanreotide (generally equivalent). Pharmacokinetic studies of LAR microsphere release profiles. Studies on gallstone risk and UDCA prophylaxis. Reviews of TPE oral delivery technology. TIER 3: Large registry data from acromegaly centers worldwide (German, Belgian, French registries). NET specialist practice protocols for carcinoid crisis management. Case series of high-dose octreotide (60 mg/month) in refractory patients. International guidelines (ENETS, NANETS) for NET management. KEY FINDINGS: Octreotide LAR is a cornerstone therapy for acromegaly and neuroendocrine tumors with decades of clinical experience. The oral formulation (Mycapssa) represents a genuine breakthrough in peptide drug delivery, though the fasting requirement and twice-daily dosing limit convenience. GAPS: No head-to-head trial of octreotide vs. pasireotide (multi-receptor SSA) for acromegaly. Optimal duration of antiproliferative therapy in NETs undefined. Long-term outcomes with oral Mycapssa limited. Biomarkers predicting response vs. non-response poorly validated. ACTIVE TRIALS: Ongoing studies of oral octreotide in NETs. Combination trials (octreotide + everolimus, octreotide + pegvisomant). Extended follow-up of PROMID/CLARINET cohorts.