Direct-acting vasodilators: Nursing Pharmacology

00:00 / 00:00

Notes

Notes

DIRECT-ACTING VASODILATORS
DRUG NAME
hydralazine (Apresoline), minoxidil (Loniten), 
sodium nitroprusside (Nipride, Nitropress) 
*High Alert Medication*
CLASS
Direct-acting vasodilators
MECHANISM OF ACTION
Prevent the increase of intracellular calcium concentration within vascular smooth muscle cells → vasodilation → reduced total peripheral resistance and blood pressure
INDICATIONS
  • Severe refractory hypertension
  • Malignant hypertension
  • Hypertensive emergencies
ROUTE(S) OF ADMINISTRATION
  • Hydralazine: PO, IV, IM
  • Minoxidil: PO
  • Sodium nitroprusside: IV
SIDE EFFECTS
  • Hypotension
  • Dizziness
  • Headache
  • Reflex tachycardia
  • Palpitations
  • Edema
  • Nausea
  • Vomiting
  • GI distress
  • Minoxidil: pericardial effusion (boxed warning), cardiac tamponade
  • Nitroprusside: Cyanide poisoning (boxed warning), hypothyroidism
CONTRAINDICATIONS AND CAUTIONS
  • Cerebrovascular insufficiency
  • Peripheral vascular disease
  • Coronary artery disease
  • Heart failure
  • Mitral valve disease
  • Pregnancy and breastfeeding
  • Septic shock
NURSING CONSIDERATIONS: DIRECT-ACTING VASODILATORS
ASSESSMENT AND MONITORING
Baseline assessment
  • Vital signs, ECG, heart and lung sounds, weight, CBC, electrolytes, hepatic and renal function

Hydralazine IV
  • Patent IV access
  • Frequent vital signs; signs of fluid overload - edema, pulmonary crackles, orthopnea

Nitroprusside IV
  • Continuous cardiorespiratory monitoring
  • Automatic blood pressure monitoring
  • Patent IV access
  • Emergency equipment and sodium thiosulfate readily available
  • Double-check infusion pump settings with a second nurse
  • Monitor for extravasation
  • Assess for signs of toxicity: altered mental status, agitation, tremor
  • For suspected toxicity, stop the infusion and notify the physician immediately; prepare to administer antidote
CLIENT EDUCATION
  • Concurrent use of beta-blocker and diuretic
  • Report signs of water retention, shortness of breath, fast heart beat (reflex tachycardia), chest pain

Hydralazine
  • Take with meals
  • Report side effects: symptoms of lupus-like syndrome: muscle aches, joint pain, fever

Minoxidil
  • Take without regard to meals
  • Can cause reversible increase in hair growth

Nitroprusside
  • Report burning or stinging at IV site, tinnitus

Transcript

Direct-acting vasodilators are a class of antihypertensive medications that are used for severe refractory hypertension, malignant hypertension, and hypertensive emergencies. These medications include hydralazine, which can be administered orally, intravenously, and intramuscularly; minoxidil, which can be administered orally or topically; and sodium nitroprusside, which is given intravenously.

Once administered, direct acting vasodilators rapidly work on the vascular smooth muscle cells by preventing the increase of intracellular calcium concentration.

As a result, direct acting vasodilators prevent vasoconstriction and promote vasodilation, leading to a reduction in the total peripheral resistance and blood pressure.

Keep in mind that hydralazine and minoxidil mainly work on arterioles, while sodium nitroprusside works on both arterioles and venules.

Now, since direct acting vasodilators tend to work rapidly, they can result in sudden vasodilation and hypotension. This may lead to side effects, including dizziness, headache, reflex tachycardia, palpitations, and edema.

Other side effects include nausea, vomiting, and gastrointestinal distress. So to counteract side effects like reflex tachycardia and edema, direct acting vasodilators can be used in combination with beta-blockers or diuretics, but under close monitoring for adverse effects.

Now, through an unclear mechanism, hydralazine may trigger a lupus-like syndrome, which can involve multiple organs. Clients may experience severe malaise, myalgia, arthralgia, pericarditis, and hepatosplenomegaly, and upon blood tests, they may present with leukopenia, thrombocytopenia, and positive autoantibodies.

Sources

  1. "Focus on Nursing Pharmacology" LWW (2019)
  2. "Pharmacology" Elsevier Health Sciences (2014)
  3. "Mosby's 2021 Nursing Drug Reference" Mosby (2020)
  4. "Saunders Comprehensive Review for the NCLEX-RN Examination" Saunders (2016)
Elsevier

Copyright © 2023 Elsevier, its licensors, and contributors. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Cookies are used by this site.

USMLE® is a joint program of the Federation of State Medical Boards (FSMB) and the National Board of Medical Examiners (NBME). COMLEX-USA® is a registered trademark of The National Board of Osteopathic Medical Examiners, Inc. NCLEX-RN® is a registered trademark of the National Council of State Boards of Nursing, Inc. Test names and other trademarks are the property of the respective trademark holders. None of the trademark holders are endorsed by nor affiliated with Osmosis or this website.

RELX