Pharmacology of liver

Lliver, being an important metabolic organ has altered pharmacodynamics and pharmacokinetics of drugs in severe liver diseases

Pharmacodynamics

	Increase sensitivity to neuroleptics and sedatives, opioids and antiepileptics drugs occur in liver diseases.
	Oral anticoagulants have increase effects
	Fluid and electrolyte balance are disrupted. Sodium retention is high in nonsteroidal antiflammatory drug administration and subcutaneous edema and ascites are more resistant to diuretics.

Pharmacokinetics

The is decreased plasma clearance of which are metabolized in the liver in liver diseases and hepatocellular injury

Hepatocellular injury

Drugs can damage the liver and they are classified into thee main types of injury

	Type A: Dose dependent damage
	Type B: Dose unrelated and may cause damage in normal therapeutic doses
	Type C: Drugs my cause the development of liver tumors

Liver pharmacotherapy

Ascites: Perform pharmacotherapeutic natriuresis with loss of water in addition to sodium restriction in diet. Use spironolactone with the addition of a loop diuretic such as frusemide.

Treatment of complications of cirrhosis: Use nonselective β adrenergic blockers for example propranolol or nadolol which reduce cardiac output through β₁ receptor antagonistic action with induction of a splanchnic vasoconstriction which has β₂ receptor antagonism with consequent unopposed α -adrenergic vasoconstriction.

Hepatic encephalopathy occurs in severe liver failure due to inavailability of normal conjugation processes for toxic food and drugs in the liver. Ammonia is the main culprit toxic substance. Drugs used to combat this include those which limit the production of ammonia such as lactulose with reduction in dietary protein.

Immune diseases of liver: In immune diseases of the liver such as automimmune chronic active hepatitis, steroids are used for treatment such as prednisolone combination with azathioprine.

Primary biliary cirrhosis: Treatment is not well recognized but steroids such as predisolone can be used. Budesonide is being tried while ursodeoxycholic acid improves liver function tests without any evidence of increased survival rates.

Hepatitis

Hepatitis A: Intramuscular injection of normal immunoglobluin to virus. Also active immunization with hepatitis A vaccine is now used.

Hepatitis B: Interferon alfa can be used. Also lamivudine which is nucleoside analogue. Hepatitis B immunization is also used whether as vaccine or immunoglobulin.

Hepatitis C: Combination of interferon alfa and ribavirin is useful.

Hepatitis D: It is difficult to treat and interferon alfa is less effective when compared to other hepatitis types.