Vasodilators (arterial and venodilators) in management of Hypertension

Vasodilators which are used in treatment of hypertension are divided into Arterial vasodilators, Venodilators and both ( arterial and veno- dilators ) .
Use of Vasodilators in management of Hypertension

A. Arterial vasodilators

Hydralazine (Apresoline).
- Now it has little place in the routine oral therapy.
- Used with pregnancy, it can be used in hypertensive encephalopathy by infusion .
- It leads to reflex increase in Heart rate which results in decreased coronary filling.
- Dose is up to 100 mg/day, in hypertensive emergency .
- Side effects :
  • SLE like synd.
  • Tachycardia - Headache - flushing .
Calcium channel blockers:
- Nifedipine 10-20mg /8hr .
- Amlodipine 5-10mg/d.
- Deltiazem 60-180mg/12hr.
- Verpami1120-480 mg/d .

Diazoxide
- Very potent .
- Inhibits insulin release ((Used in insulinoma) .
- IV 1-3 mg/kg in cases of hypertensive encephalopathy it is given rapidly .

B. Venodilators 

They are converted to nitric oxide which causes vasodilatation .
They can be used by infusion in case of hypertensive encephalopathy i.e glyceryl trinitrate (Tridil) 0.3-1 ug/kg/m .

Other uses:
  • Oesophageal spasm and achalasia.
  • Reliefe of pulmonary venous congestion .
  • Myocardial infarction.
  • Biliary colic and hypertensive encephalopathy.
Side effects: Headache - Hypotension 


C. Arterial and Venodilators 

Na Nitroprusside  (Niprid)
- Very potent.
- Used in emergency ( H. encephalopathy , Cardiogenic pulmonary edema ) .
Dose:

50 mg vial, start with 0.3-1 ug/kg/m, the control of blood pressure is established at 0.5-6 ug/kg/m ,maximum dose is 10 ug/kg/m.
Side Effects : 
Hypotension, cyanide or thiocynate toxicity.
- Na nitroprusside converted to cyanide which is converted to thiocynate by the liver, thiocynate excreted in urine.
Liver disease: Cyanide toxicity. "Pink color, dilated pupil"
Renal disease: Thiocynate toxicity. "Tinitus, skin rash" 

Alpha blockers  :  Discussed Here 

Angiotensin Converting Enzyme Inhibitors ( ACE Inhibitors )

Side effects :
  • Hyperkalemia, skin rash.
  • Nephrotic syndrome (Membranous GN) .
  • Dry cough due to accumulation of bradykinin in the lung .
- ACE inhibitors reduce the process of ventricular remodeling.
- ACE inhibitor contraindicated in bilateral renal artery stenosis.
OTHER ACE INHIBITORS:
  • Ramipril 2.5-10 mg/d (Tritace).
  • Lisinopril Long acting 10-20 mg/d (Zestril).
  • Enalapril 10-20 mg/day oral (Ezapril), it can be given IV.
  • Tranclolanril 1-4mg-/dav.
Angiotensin II Receptor Blockers (ARBs) 
This group shares many of actions of ACE inhibitors but they do not cause cough. So, they are used for patients who can not tolerate ACE inhibitors.
 They include losatran 50-100 mg/D (Cozar) and valsartan 80-160 mg/D (Tareg) .

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