OCTREOTIDE — octreotide acetate
Fresenius Kabi USA, LLC
Octreotide Acetate Injection, a cyclic octapeptide prepared as a clear sterile solution of octreotide, acetate salt, in a buffered acetate solution for administration by deep subcutaneous (intrafat) or intravenous (IV) injection. Octreotide acetate, known chemically as L-Cysteinamide, D-phenylalanyl-L-cysteinyl-L-phenylalanyl-D-tryptophyl-L-lysyl-L-threonyl-N-[2-hydroxy-1-(hydroxymethyl)propyl]-, cyclic (2→ 7)-disulfide; [R-(R*, R*)] acetate salt, is a long-acting octapeptide with pharmacologic actions mimicking those of the natural hormone somatostatin.
Octreotide Acetate Injection is available as: sterile 1 mL single dose vials in 2 strengths, containing 100 mcg and 500 mcg octreotide (as acetate).
Each mL of the single dose vial also contains:
sodium chloride . . . . . . . . . . . . . . . . . 7 mg
glacial acetic acid, USP . . . . . . . . . . . 2 mg
sodium acetate trihydrate, USP . . . . . 2 mg
water for injection, USP . . . . . . .qs to 1 mL
The molecular weight of octreotide acetate is 1019.3 g/mol (free peptide, C49 H66 N10 O10 S2 ) and its amino acid sequence is:
Octreotide Acetate Injection exerts pharmacologic actions similar to the natural hormone, somatostatin. It is an even more potent inhibitor of growth hormone (GH), glucagon, and insulin than somatostatin. Like somatostatin, it also suppresses luteinizing hormone (LH) response to gonadotropin releasing hormone (GnRH), decreases splanchnic blood flow, and inhibits release of serotonin, gastrin, vasoactive intestinal peptide (VIP), secretin, motilin, and pancreatic polypeptide.
By virtue of these pharmacological actions, octreotide has been used to treat the symptoms associated with metastatic carcinoid tumors (flushing and diarrhea), and VIP secreting adenomas (watery diarrhea).
Octreotide substantially reduces GH and/or insulin growth factor-1 (IGF-1; somatomedin C) levels in patients with acromegaly.
Single doses of octreotide have been shown to inhibit gallbladder contractility and to decrease bile secretion in normal volunteers. In controlled clinical trials, the incidence of gallstone or biliary sludge formation was markedly increased (see WARNINGS).
Octreotide suppresses secretion of thyroid stimulating hormone (TSH).
After subcutaneous injection, octreotide is absorbed rapidly and completely from the injection site. Peak concentrations of 5.2 ng/mL (100-mcg dose) were reached 0.4 hours after dosing. Using a specific radioimmunoassay, intravenous (IV) and subcutaneous doses were found to be bioequivalent. Peak concentrations and area under the curve (AUC) values were dose proportional after IV single doses up to 200 mcg and subcutaneous single doses up to 500 mcg and after subcutaneous multiple doses up to 500 mcg 3 times a day (1,500 mcg/day).
In healthy volunteers, the distribution of octreotide from plasma was rapid (tα 1/2 = 0.2 h), the volume of distribution (Vdss ) was estimated to be 13.6 L, and the total body clearance ranged from 7 L/hr to 10 L/hr. In blood, the distribution into the erythrocytes was found to be negligible and about 65% was bound in the plasma in a concentration-independent manner. Binding was mainly to lipoprotein and, to a lesser extent, to albumin.
The elimination of octreotide from plasma had an apparent half-life of 1.7 to 1.9 hours compared with 1 to 3 minutes with the natural hormone. The duration of action of Octreotide Acetate Injection is variable but extends up to 12 hours depending upon the type of tumor. About 32% of the dose is excreted unchanged into the urine. In an elderly population, dose adjustments may be necessary due to a significant increase in the half-life (46%) and a significant decrease in the clearance (26%) of the drug.
In patients with acromegaly, the pharmacokinetics differs somewhat from those in healthy volunteers. A mean peak concentration of 2.8 ng/mL (100-mcg dose) was reached in 0.7 hours after subcutaneous dosing. The volume of distribution (Vdss ) was estimated to be 21.6 ± 8.5 L, and the total body clearance was increased to 18 L/h. The mean percent of the drug bound was 41.2%. The disposition and elimination half-lives were similar to normals.
In patients with renal impairment, the elimination of octreotide from plasma was prolonged and total body clearance reduced. In mild renal impairment (CLCR 40 to 60 mL/min), octreotide t1/2 was 2.4 hours and total body clearance was 8.8 L/hr, in moderate impairment (CLCR 10 to 39 mL/min) t1/2 was 3 hours and total body clearance 7.3 L/hr, and in severely renally impaired patients not requiring dialysis (CLCR <10 mL/min) t1/2 was 3.1 hours and total body clearance was 7.6 L/hr. In patients with severe renal failure requiring dialysis, total body clearance was reduced to about half that found in healthy subjects (from approximately 10 L/hr to 4.5 L/hr).
Patients with liver cirrhosis showed prolonged elimination of drug, with octreotide t1/2 increasing to 3.7 hr and total body clearance decreasing to 5.9 L/hr, whereas patients with fatty liver disease showed t1/2 increased to 3.4 hr and total body clearance of 8.2 L/hr.
INDICATIONS AND USAGE
Octreotide Acetate Injection is indicated to reduce blood levels of growth hormone (GH) and insulin growth factor-1 (IGF-1; somatomedin C) in acromegaly patients who have had inadequate response to or cannot be treated with surgical resection, pituitary irradiation, and bromocriptine mesylate at maximally tolerated doses. The goal is to achieve normalization of GH and IGF-1 (somatomedin C) levels (see DOSAGE AND ADMINISTRATION). In patients with acromegaly, Octreotide Acetate Injection reduces GH to within normal ranges in 50% of patients and reduces IGF-1 (somatomedin C) to within normal ranges in 50% to 60% of patients. Since the effects of pituitary irradiation may not become maximal for several years, adjunctive therapy with Octreotide Acetate Injection to reduce blood levels of GH and IGF-1 (somatomedin C) offers potential benefit before the effects of irradiation are manifested.
Improvement in clinical signs and symptoms, or reduction in tumor size or rate of growth, were not shown in clinical trials performed with Octreotide Acetate Injection; these trials were not optimally designed to detect such effects.
Octreotide acetate is indicated for the symptomatic treatment of patients with metastatic carcinoid tumors where it suppresses or inhibits the severe diarrhea and flushing episodes associated with the disease.
Octreotide acetate studies were not designed to show an effect on the size, rate of growth, or development of metastases.
Vasoactive Intestinal Peptide Tumors (VIPomas)
Octreotide acetate is indicated for the treatment of the profuse watery diarrhea associated with VIP-secreting tumors. Octreotide acetate studies were not designed to show an effect on the size, rate of growth, or development of metastases.
Sensitivity to this drug or any of its components.
Cholelithiasis and Complications of Cholelithiasis
Single doses of Octreotide Acetate Injection have been shown to inhibit gallbladder contractility and decrease bile secretion in normal volunteers. In clinical trials (primarily patients with acromegaly or psoriasis), the incidence of biliary tract abnormalities was 63% (27% gallstones, 24% sludge without stones, 12% biliary duct dilatation). The incidence of stones or sludge in patients who received octreotide acetate for 12 months or longer was 52%. Less than 2% of patients treated with octreotide acetate for 1 month or less developed gallstones. The incidence of gallstones did not appear related to age, sex, or dose. Like patients without gallbladder abnormalities, the majority of patients developing gallbladder abnormalities on ultrasound had gastrointestinal symptoms. The symptoms were not specific for gallbladder disease. A few patients developed acute cholecystitis, ascending cholangitis, biliary obstruction, cholestatic hepatitis, or pancreatitis during octreotide acetate therapy or following its withdrawal. One patient developed ascending cholangitis during octreotide acetate therapy and died. There have been postmarketing reports of cholelithiasis (gallstones) resulting in complications requiring cholecystectomy.
If complications of cholelithiasis are suspected, discontinue octreotide acetate and treat appropriately.
Complete Atrioventricular Block
Patients who receive Octreotide Acetate Injection intravenously may be at increased risk for higher degree atrioventricular blocks. In postmarketing reports, complete atrioventricular block was reported in patients receiving intravenous octreotide acetate during surgical procedures. In majority of patients, octreotide acetate was given at higher than recommended doses and/or as a continuous intravenous infusion. The safety of continuous intravenous infusion has not been established in patients receiving octreotide acetate for the approved indications. Consider cardiac monitoring in patients receiving octreotide acetate intravenously.
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