Drug Treatment of Leprosy

Drugs Used for leprosy

• Dapsone
• Rifampicin
• Clofazimine

Treatment of leprosy

Initial phase -6-12 month

• Dapsone 50 – 100mg o.d
• Clofazimine  50 – 100mg o.d
• Rifampicin 600mg monthly

Continuation phase

• Dapsone 50 – 100mg o.d for 2 -3 years

Dapsone

it is a chemically related sulfonamides.

Mechanism of action

Same as that of sulfonamides. It acts by inhibiting folic acid synthetase.

Antibacterial spectrum

Mainly acts against:

1. Mycobacterium leprae
2. Effective against plasmodium
3. Drug is effective against pneumocystitis kerani or jerovaci.

Pharmacokinetics

Well absorbed after oral administration. Distributed mainly to skin, liver, kidneys and reticuloendothelial cells. Drug cannot penetrate into CNS. It is mainly metabolized by acetylation.

Half life is 1-2 days.

Therapeutic uses

1. Treatment of leprosy in combination with other drugs
2. Treatment of immunocompromised patients having pneumonia caused by pneumocystitis kerani or jerovaci.
3. Treatment of malaria especially prophylaxis of malaria in combination with pyrimethamine.
4. Also used in non-infectious skin disorders known as dermatitis herpeteformis

Adverse effects

As is a sulfonamide, can cause:

1. Crystal uria
2. Allergic reactions
3. Skin rashes
4. Blood dyscrasias (leukopoenia, thrombocytopenia)
5. GIT upsets

Dose 50-100 mg once daily

Clofazimine

Chemically phenazine derivative.

Mechanism of action

Acts by two mechanisms:

1. Binds DNA and interferes with replication.
2. Has redox properties, it is converted into oxygen radicals which act as cytotoxic agents for bacteria.

Pharmacokinetics

Drug is mainly absorbed after oral administration. It has high volume of distribution and accumulates in various tissues, reticuloendothelial cells, liver, kidneys, etc.

Half life is very high, more than dapsone. (72 hours).

Uses

Mainly used for the treatment of leprosy in combination with other drugs.

Adverse effects

1. Causes discolouration of skin (blackish to brown)
2. May also cause GIT upsets.
3. Enteritis, which has allergic basis.

Dose Same as that of dapsone 50-100 mg once daily.

Lepra reactions

During treatment of leprosy certain reactions occur, known as lepra reactions. These have immunological basis, due to allergies. They are of two types:

1. Reversal reaction
   Skin and nerve lesion without systemic effects

2. Erythema nodosum leprosum

Systemic effects like fever etc.

Treatment
Prednisolone 60mg/day or Thalidomide 300mg/day.

Pregnant females are not given thalidomide as is teratogenic (limb abnormality).