Archive for the ‘ L3-Pharma TB ’ Category

L3- Pharmacological of Antituberculosis

Tuberculosis

-Tuberculosis (TB) remains the leading cause of death worldwide from a single infectious disease agent. Indeed up to 1/2 of the world’s population is infected with TB.

-The registered number of new cases of TB worldwide roughly correlates with economic conditions: the highest incidences are seen in those countries of Africa, Asia, and Latin America with the lowest gross national products.

-WHO estimates that eight million people get TB every year, of whom 95% live in developing countries. An estimated 2 million people die from TB every year

-It is estimated that between 2000 and 2020, nearly one billion people will be newly infected, 200 million people will get sick, and 35 million will die from TB – if control is not further strengthened.

-The mechanisms, pathogenesis, and prophylaxis knowledge is minimal.

-After a century of decline TB is increasing and there are strains emerging which are resistant to antibiotics.

-This excess of cases is attributable to

  1. the changes in the social structure in cities,
  2. the human immunodeficiency virus epidemic ,
  3. the failure of most cities to improve public health programs,
  4. the economic cost of treating

-TB is an ancient infectious disease caused by Mycobacterium tuberculosis. It has been known since 1000 B.C., so it not a new disease. Since TB is a disease of respiratory transmission, optimal conditions for transmission include:

  1. overcrowding
  2. poor personal hygiene
  3. poor public hygiene

-With the increased incidence of AIDS, TB has become more a problem in the U.S., and the world.

-It is currently estimated that 1/2 of the world’s population (3.1 billion) is infected with Mycobacterium tuberculosis. Mycobacterium avium complex is associated with AIDS related TB.

Transmission

-Pulmonary tuberculosis is a disease of respiratory transmission, Patients with the active disease (bacilli) expel them into the air by:

  1. coughing,
  2. sneezing,
  3. shouting,
  4. or any other way that will expel bacilli into the air

-Once inhaled by a tuberculin free person, the bacilli multiply 4 -6 weeks and spreads throughout the body.

-The bacilli implant in areas of high partial pressure of oxygen:

  1. lung
  2. renal cortex
  3. reticuloendothelial system

-This is known as the primary infection.

-The patient will heal and a scar will appear in the infected loci.

-There will also be a few viable bacilli/spores may remain in these areas (particularly in the lung).

-The bacteria at this time goes into a dormant state, as long as the person’s immune system remains active and functions normally, this person isn’t bothered by the dormant bacillus.

-When a person’s immune system is depressed., a secondary reactivation occurs.

-85-90% of the cases seen which are of secondary reactivation type occurs in the lungs.

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Mycobacterium tuberculosis

-gram   +ve bacilli

-Non motile, non sporing,& noncapsulated

-Strict aerobes

-Branching filamentous forms ≈ fungal mycelium =MYCOBACTERIUM

-A.F.B = when stained by Carbol Fuschin by Z-N Stain they resist decolorisation by 25% H2S04 & Abs.alcohol

-Cell wall is lipid rich  with mycolic acid which is essential & unique component

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Classification of Drugs

-3 Groups depending upon the degree of effectiveness and potential side effects

First Line: (Primary agents)

-are the most effective and have lowest toxicity.

-Isoniazid Rifampin

Second Line:

-Less effective and more toxic effects

-include (in no particular order):  amino salicylic acid, Streptomycin, Ethambutol

Third Line

-are least effective and most toxic.

-Amikacin, Kanamycin, Capreomycin, Viomycin, Kanamycin, Cycloserine

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