vasopressin

Alters the permeability of the renal collecting ducts, allowing reabsorption of water.
Directly stimulates musculature of GI tract.
In high doses acts as a nonadrenergic peripheral vasoconstrictor.

Therapeutic effects:

Decreased urine output and increased urine osmolality in diabetes insipidus.
Increased BP

Pharmacokinetics ⬆ ⬇

Absorption: IM absorption may be unpredictable. IV administration results in complete bioavailability.

Distribution: Well distributed to tissues.

Metabolism/Excretion: Rapidly degraded by the liver and kidneys; <5% excreted unchanged by the kidneys.

Half-Life: <10 min.

Time/Action Profile ⬆ ⬇

(antidiuretic effect)

ROUTE	ONSET	PEAK	DURATION
IM, SUBQ	unknown	unknown	2–8 hr
IV	unknown	unknown	30–60 min

Contraind./Precautions ⬆ ⬇

Contraindicated in:

Hypersensitivity to 8-L arginine vasopressin or chlorobutanol (only in multidose vial);
Chronic renal failure.

Use Cautiously in:

Perioperative polyuria (↑ sensitivity to vasopressin effects);
Comatose patients;
Seizures;
Migraine headaches;
Asthma;
HF;
Cardiovascular disease;
Renal impairment;
OB: Higher doses (0.07 units/min) for vasodilatory shock may be needed in 2nd and 3rd trimesters;
Lactation: Safety not established in breastfeeding;
Geri: Older adults may have sensitivity to effects.

Adv. Reactions/Side Effects ⬆ ⬇

CV: angina, chest pain, MI

Derm: paleness, perioral blanching, sweating

Endo: diabetes insipidus

F and E: water intoxication (higher doses)

GI: abdominal cramps, belching, diarrhea, flatulence, heartburn, nausea, vomiting

Neuro: "pounding" sensation in head, dizziness, trembling

Misc: allergic reactions, fever

Interactions ⬆ ⬇

Drug-drug:

Antidiuretic effect may be ↓ by concurrent administration of clozapine, lithium, demeclocycline, foscarnet.
Antidiuretic effect may be ↑ by concurrent administration of cyclophosphamide, enalapril, felbamate, haloperidol, ifosfamide, pentamidine, tricyclic antidepressants, SSRIs, or vincristine.
Vasopressor effect may be ↑ by concurrent administration of ganglionic blocking agents, indomethacin, or catecholamines.
Furosemide↑ urine flow

Route/Dosage ⬆ ⬇

Diabetes Insipidus

IM SC (Adults ): 5–10 units 2–4 times daily.
IM SC (Children ): 2.5–10 units 2–4 times daily.
IV (Adults and Children ): 0.0005 units/kg/hr, double dose every 30 min as needed to a maximum of 0.01 units/kg/hr.

Vasodilatory Shock

IV (Adults ): 0.01 units/min, titrate by 0.005 units/min every 10–15 min until target BP achieved (max dose = 0.07 units/min).
IV (Infants and Children): 0.0003–0.002 units/kg/min, titrate to effect.

GI Hemorrhage

IV (Adults ): 0.2–0.4 units/min then titrate to maximum dose of 0.9 units/min; if bleeding stops, continue same dose for 12 hr, then taper off over 24–48 hr.
IV (Children ): 0.002–0.005 units/kg/min then titrate to maximum dose of 0.01 units/kg/min; if bleeding stops, continue same dose for 12 hr, then taper off over 24–48 hr.

Availability ⬆ ⬇

(Generic available)

Premixed infusion: 20 units/100 mL D5W; 40 units/100 mL D5W; 60 units/100 mL D5W
Solution for injection: 20 units/mL

Assessment ⬆ ⬇

Monitor BP, HR, and ECG periodically throughout therapy and continuously throughout cardiopulmonary resuscitation.
Diabetes Insipidus: Monitor urine osmolality and urine volume frequently to determine effects of medication. Assess patient for symptoms of dehydration (excessive thirst, dry skin and mucous membranes, tachycardia, poor skin turgor). Weigh patient daily, monitor intake and output, and assess for edema.

Lab Test Considerations:

Monitor urine specific gravity during therapy.
- Monitor serum electrolyte concentrations periodically during therapy.

Toxicity and Overdose:

Signs and symptoms of water intoxication include confusion, drowsiness, headache, weight gain, difficulty urinating, seizures, and coma.
- Treatment of overdose includes water restriction and temporary discontinuation of vasopressin until polyuria occurs. If symptoms are severe, administration of mannitol, hypertonic dextrose, urea, and/or furosemide may be used.

Implementation ⬆ ⬇

Aqueous vasopressin injection may be administered SUBQ or IM for diabetes insipidus.
- Administer 1–2 glasses of water at the time of administration to minimize side effects (blanching of skin, abdominal cramps, nausea).

IV Administration:

Patient/Family Teaching ⬆ ⬇

Explain purpose of vasopressin to patient.
Advise patient to drink 1–2 glasses of water at time of administration to minimize side effects (blanching of skin, abdominal cramps, nausea). Inform patient that these side effects are not serious and usually disappear in a few min.
Caution patient to avoid concurrent use of alcohol while taking vasopressin.
Rep: Advise females of reproductive potential to notify health care professional if pregnancy is planned or suspected or if breastfeeding. Due to increased clearance of vasopressin in the second and third trimester, the dose of vasopressin may need to be increased. May produce tonic uterine contractions that could threaten the continuation of pregnancy.
Patients with diabetes insipidus should carry identification at all times describing disease process and medication regimen.

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Pronunciation ⬇

Classifications ⬆ ⬇

Indications ⬆ ⬇

Action ⬆ ⬇