Drugs used in hypotensive states and shock

Antihypotensive drugs or agents are used to elevate a low blood pressure and may be classified
as follows:
I. Agents intended to increase the volume of blood in active circulation. These include
intravenous fluids such as whole blood, plasma, plasma components, plasma substitutes
and solution of crystalloids
II. Vasoconstrictor drugs these include:

• Peripherally acting vasoconstrictors which are further divided into sympathomimetic
  drugs and direct vasoconstrictors.
  Sympathomimetics used to elevate the blood pressure include adrenaline, noradrenaline,
  methoxamine, phenylephrine, mephentermine and ephedrine.
  Direct vasoconstrictors include vasopressin and angiotensin.
  Treatment of shock
  Shock is a clinical syndrome characterized by decreased blood supply to tissues. Common
  signs and symptoms include oliguria, heart failure, disorientation, mental confusion, seizures,
  cold extremities, and comma.
  Most, but not all people in shock are hypotensive. The treatment varies with type of shock.
  The choice of drug depends primarily on the patho-physiology involved.
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  o For cardiogenic shock and decreased cardiac out put, dopamine or other cardiotonic
  drug is indicated. With severe CHF characterized by decreased CO and high PVR,
  vasodilator drugs (nitropruside, nitroglycerine) may be given along with the
  cardiotonic drug. Diuretics may also be indicated to treat pulmonary congestion if it
  occurs.
  o For anaphylactic shock or neurogenic shock characterized by severe vasodilation
  and decreased PVR, a vasoconstrictor drug (e.g. levarterenol) is the first drug of
  choice
  o For hypovolemic shock, intravenous fluids that replace the type of fluid lost should be
  given
  o For septic shock, appropriate antibiotic therapy in addition to other treatment
  measures.