Action And Clinical Pharmacology: The antidiuretic action of vasopressin is ascribed to increasing reabsorption of water by the renal tubules.
Vasopressin can cause contraction of smooth muscle of the gastrointestinal tract and of all parts of the vascular bed especially the capillaries, small arterioles and venules with less effect on the smooth musculature of the large veins. The direct effect on the contractile elements is neither antagonized by adrenergic blocking agents nor prevented by vascular denervation.
Indications And Clinical Uses: Prevention and treatment of postoperative abdominal distention, in abdominal roentgenography to dispel interfering gas shadows, and in diabetes insipidus.
Contra-Indications: Anaphylaxis or hypersensitivity to the drug or its components.
Manufacturers’ Warnings In Clinical States: This drug should not be used in patients with vascular disease, especially disease of the coronary arteries, except with extreme caution. In such patients, even small doses may precipitate anginal pain, and with larger doses, the possibility of myocardial infarction should be considered.
Vasopressin may produce water intoxication. The early signs of drowsiness, listlessness, and headaches should be recognized to prevent terminal coma and convulsions.
Precautions: Vasopressin should be used cautiously in the presence of epilepsy, migraine, asthma, heart failure or any state in which a rapid addition to extracellular water may produce hazard for an already overburdened system.
Chronic nephritis with nitrogen retention contraindicates the use of vasopressin until reasonable nitrogen blood levels have been attained.
Adverse Reactions: Local or systemic allergic reactions may occur in hypersensitive individuals. The following side effects have been reported following the administration of vasopressin: tremor, sweating, vertigo, circumoral pallor, “pounding” in head, abdominal cramps, passage of gas, nausea, vomiting, urticaria, bronchial constriction. Anaphylaxis (cardiac arrest and/or shock) have been observed shortly after injection of vasopressin.
Dosage And Administration: May be administered i.m. or s.c.
Ten units (0.5 mL) will usually elicit full physiologic response in adult patients: 5 units (0.25 mL) will be adequate in many cases. Should be given i.m. at 3- or 4-hour intervals as needed. The dosage should be proportionately reduced for children. (For an additional discussion of dosage, consult the sections below.)
When determining the dose of vasopressin injection for a given case, the following should be kept in mind: It is particularly desirable to give a dose not much larger than is just sufficient to elicit the desired physiologic response. Excessive doses may cause undesirable side actions-blanching of the skin, abdominal cramps, nausea-which, though not serious, may be alarming to the patient. Spontaneous recovery from such side actions occurs in a few minutes. It has been found that 1 or 2 glasses of water given at the time vasopressin injection is administered reduces such symptoms.
Abdominal Distention: In the average postoperative adult patient, give 5 units (0.25 mL) initially, increase to 10 units (0.5 mL) at subsequent injections if necessary. It is recommended that vasopressin injection be given i.m. and that injections be repeated at 3- or 4-hour intervals as required. Dosage to be reduced proportionately for children.
Vasopressin injection used in this manner will frequently prevent, or relieve, postoperative distention. These recommendations apply also to distention complicating pneumonia or other acute toxemias.
Abdominal Roentgenography: For the average case, 2 injections of 10 units (0.5 mL) each are suggested. These should be given 2 hours and 1/2 hour, respectively before films are exposed. Many roentgenologists advise giving an enema prior to the first dose of vasopressin injection.
Diabetes Insipidus: May be given by injection or administered intranasally on cotton pledgets, by nasal spray, or by dropper. The dose by injection is 5 to 10 units (0.25 to 0.5 mL) repeated 2 or 3 times daily as needed. When it is administered intranasally by spray or on pledgets, the dosage and interval between treatments must be determined for each patient.
Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit.
Availability And Storage: Each mL of sterile, nonpyrogenic solution contains: vasopressin 20 USP pressor units, chlorobutanol 5 mg as preservative, water for injection q.s., glacial acetic acid and/or sodium hydroxide for pH adjustment (2.5 to 4.5). Flip-top vials of 1 mL (partially filled in 2 mL vial), packages of 25. Store at 15 to 30°C. Do not permit to freeze.
VASOPRESSIN INJECTION Pharmaceutical Partners Antidiuretic Agent