SECTION 4 — POSTERIOR PITUITARY HORMONE DRUGS (Desmopressin)

What is the prototype posterior pituitary drug?

Desmopressin (DDAVP, Stimate).

Desmopressin is a synthetic analog of what?

ADH.

Main clinical use of desmopressin?

Neurogenic Diabetes Insipidus (DI).

Other uses of desmopressin?

Hemophilia A, von Willebrand disease.

Main action of desmopressin?

↑ Water reabsorption in kidneys.

What is cAMP’s role in desmopressin action?

Increases water permeability of kidney tubules.

What happens to urine output with desmopressin?

Decreases.

What happens to urine osmolality?

Increases.

What clotting factors does desmopressin affect?

vWF, Factor VIII, tissue plasminogen activator.

Onset for intranasal form?

15–30 mins.

Onset for IV form?

30 mins.

Onset for oral form?

60 mins.

Duration of desmopressin?

6–14 hours.

Excretion of desmopressin?

Urine.

Main contraindication?

Creatinine clearance <50 mL/min.

BLACK BOX warning for desmopressin?

Severe hyponatremia → seizures, death.

Second BLACK BOX warning?

Fluid shifts → cardiac arrest in heart disease.

Common adverse effects?

Injection site reactions, headache, dizziness, lethargy.

Nasal-specific effects?

Nasal irritation, congestion.

GI adverse effects?

Heartburn, cramping.

What is most important lab to monitor?

Serum sodium.

Normal serum sodium range?

135–145 mEq/L.

Normal serum osmolality?

285–295 mOsm/kg.

What symptom signals hyponatremia?

Confusion, seizures.

Therapeutic goal of desmopressin in DI?

Normalize urine output & osmolality.

Signs of dehydration to monitor?

Skin turgor, mucous membranes, thirst.

Administration for bleeding disorders?

IV over 15–30 mins.

What must be ensured before intranasal use?

Nasal passages clear.

How is nasal dose given?

Nasal spray pump or calibrated tube.

Does alcohol affect desmopressin?

Yes — decreases effect.

What drugs increase desmopressin effect?

Carbamazepine, chlorpropamide, SSRIs, TCAs.

Major risk in elderly or cardiac patients?

Fluid overload → cardiac arrest.

Pregnancy use?

Safe — continue during pregnancy.

Breastfeeding?

Present in milk but acceptable.

Important teaching for parents?

Report lethargy, seizures, weight gain.

Why monitor children for hyponatremia?

Children more prone to water intoxication.

When should dosage be held?

If signs of fluid overload or hyponatremia.

Why is fluid restriction important?

Prevent hyponatremia.

Goal urine specific gravity?

↑ toward normal.

What patient population has most risk?

Cardiac and renal impaired patients.

Why avoid nasal form with congestion?

May alter absorption.

If sodium <130, what should nurse do?

Hold desmopressin and notify provider.

Important for patient on nasal spray?

Use correct technique.

Should fluid intake be encouraged?

No — should be restricted.

How does desmopressin help vWF disease?

Increases vWF and Factor VIII.

When should effectiveness be reassessed?

After each dose adjustment.

Main cause of death in overdose?

Severe hyponatremia.

Patient teaching for nasal tube use?

Blow into tube → spray into nostril.

What electrolyte most important to assess?

Sodium.

How often is oral form given?

BID (twice daily).