Doxazosin

Doxazosin

[1 tablet 7 cents]

ADMINISTRATION ROUTES:

• PO, NG

ALTERNATIVE NAMES:

• Dosan, Apo-Doxazosin

ICU INDICATIONS:

1. hypertension refractory to other oral agents
2. patients may also be taking this medication at the time of ICU admission for benign prostatic hypertrophy (it is usually appropriate to withhold doxazosin given for this indication)

PRESENTATION AND ADMINISTRATION:

• PO:
  Apo-Doxazosin 2mg (white), Apo-Doxazosin 4mg (white), Dosan 4mg (white)

DOSAGE:

• PO/ NG:
  Commence with 1mg daily Increase as required. Maximum 16mg daily

DOSAGE IN RENAL FAILURE AND RENAL REPLACEMENT THERAPY:

• Dose as in normal renal function

DOSAGE IN PAEDIATRICS:

• PO:
  0.02-0.1mg/kg daily

CLINICAL PHARMACOLOGY:

• Doxazosin mesylate is a selective inhibitor of the alpha1-subtype of alpha adrenergic receptors.

CONTRAINDICATIONS

1. known hypersensitivity to doxazosin

WARNINGS

• First-Dose Effect:
  Doxazosin, like other alpha-adrenergic blocking agents, can cause marked hypotension, particularly with the first dose.
• Priapism:
  Doxazosin may cause priapism; if this occurs, urgent urological advice is required.

PRECAUTIONS

• General:
  Doxazosin should be administered with caution to patients with evidence of impaired hepatic function
  
• Laboratory Tests:
  No tests additional to routine ICU tests are required.
• Drug/Laboratory Test Interactions:
  None known.

IMPORTANT DRUG INTERACTIONS FOR THE ICU

Hypotension is more likely to occur when doxazosin is combined with other antihypertensives

ADVERSE REACTIONS

• Body as a Whole:
  Malaise
• Cardiovascular System:
  Dizziness, hypotension
• Skin & Appendages:
  Rash
• Central & Peripheral Nervous System:
  Headache, paresthesia, muscle cramps, somnolence
• Gastrointestinal System:
  Nausea, diarrhoea, constipation
• Respiratory System:
  Rhinitis