Ornipressin
Description
Chemical Structure and Properties
Ornipressin is a 9-amino acid peptide with the sequence H-Cys-Tyr-Phe-Gln-Asn-Cys-Pro-Orn-Gly-NH₂ (disulfide bridge between Cys1 and Cys6) . Key properties include:
| Property | Value | Source |
|---|---|---|
| Molecular Formula | C₄₅H₆₃N₁₃O₁₂S₂ | |
| Molecular Weight | 1042.19 g/mol | |
| Synonyms | Ornipressine, POR-8, 8-L-Ornithinevasopressin | |
| Storage | Lyophilized; stored at -18°C | |
| Purity | >97% (RP-HPLC) |
Mechanism of Action
Ornipressin primarily activates V1 vasopressin receptors, inducing intense vasoconstriction. This action is mediated by intracellular calcium mobilization, leading to smooth muscle contraction . Unlike natural vasopressin, it exhibits reduced antidiuretic (V2 receptor) activity, minimizing renal side effects .
Hemostasis in Surgery
Ornipressin is used as a local vasoconstrictor to reduce bleeding during procedures. Key applications include:
Key Insight: Higher concentrations (e.g., 5 IU/10 mL lidocaine) enhance hemostasis but may elevate blood pressure under certain anesthetics (e.g., diazepam/fentanyl) .
Management of Hypotension
Ornipressin is effective in counteracting hypotension induced by combined general/epidural anesthesia. A study of 60 patients undergoing intestinal surgery demonstrated:
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Faster BP restoration (8 ± 2 minutes vs. 7 ± 3 minutes with norepinephrine and 11 ± 3 minutes with dopamine) .
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Low ischemic risk: No significant ST-segment changes or lactate elevation .
Renal Dysfunction
In cirrhotic patients with functional renal failure, ornipressin infusion (6 IU/h for 4 hours) improves renal function by:
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Increasing inulin clearance (+65%) and renal blood flow (+44%) .
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Reducing sympathetic activity: Plasma noradrenaline and renin levels decreased by 46% and 49%, respectively .
Comparative Efficacy
Adverse Effects
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Splanchnic vasoconstriction: Elevated gastric intramucosal PCO₂ observed in hypotension studies .
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Hypertension risk: Observed under diazepam/fentanyl anesthesia, particularly with high-dose infiltration .
Drug Interactions
Research Gaps and Future Directions
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Neuroprotective potential: Limited data on cerebral ischemia applications .
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Hepatorenal syndrome (HRS): Pooled analyses suggest ornipressin may improve kidney function in HRS when mean arterial pressure (MAP) rises, but direct clinical trials are needed .
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Dosage optimization: Higher concentrations (e.g., 5 IU/10 mL) improve hemostasis but require careful monitoring in hypertensive patients .
Product Specs
H-Cys-Tyr-Phe-Gln-Asn-Cys-Pro-Orn-Gly-NH2.
Product Science Overview
Ornipressin has a complex chemical structure, with the IUPAC name (2S)-N-[(2S)-5-Amino-1-[(2-amino-2-oxoethyl)amino]-1-oxopentan-2-yl]-1-[(4R,7S,10S,13S,16S,19R)-19-amino-7-(2-amino-2-oxoethyl)-10-(3-amino-3-oxopropyl)-16-[(4-hydroxyphenyl)methyl]-6,9,12,15,18-pentaoxo-13-(phenylmethyl)-1,2-dithia-5,8,11,14,17-pentazacycloicosane-4-carbonyl]pyrrolidine-2-carboxamide . It has a molecular formula of C45H63N13O12S2 and a molar mass of 1042.19 g/mol .
Ornipressin is primarily used as a vasoconstrictor and haemostatic agent. It is effective in controlling bleeding during surgeries and in treating conditions like esophageal varices, where blood vessels in the esophagus become enlarged and prone to bleeding . Additionally, it has been used in the management of adrenaline-resistant anaphylaxis, a severe allergic reaction that does not respond to standard adrenaline treatment .
Ornipressin works by binding to vasopressin receptors in the blood vessels, causing them to constrict. This vasoconstriction helps to increase blood pressure and reduce blood flow to certain areas, which is particularly useful in controlling bleeding . It also has antidiuretic properties, meaning it can reduce urine production by increasing water reabsorption in the kidneys .
- Surgical Procedures: Ornipressin is often used during surgeries to control bleeding and maintain stable blood pressure. Its vasoconstrictive properties make it an effective agent in reducing blood loss.
- Anaphylaxis Management: In cases of adrenaline-resistant anaphylaxis, ornipressin has been shown to be effective in restoring blood pressure and heart rate when standard treatments fail .
- Esophageal Varices: Ornipressin is used to manage bleeding from esophageal varices, which are dilated blood vessels in the esophagus that can rupture and cause significant bleeding .
While ornipressin is generally effective, it can have side effects, including hypertension (high blood pressure), bradycardia (slow heart rate), and potential allergic reactions. It is important for healthcare providers to monitor patients closely when administering this medication to manage any adverse effects promptly .
