Interacting drugs- summary

+Chloroquine

Cimetidine

 cimetidine reduce oral clearanc rate of chloroquine

Kaolin / Magnesium silicate

 GI absorption of chloroquine decreased by cocomittant admin. of these agents 

Prophylaxis and treatment of malaria.

Cardiovascular -

Hypotension, ECG changes ( particularly inversion or depression of the T wave, widening of QRS complex.)

CNS -

Mild, transcient headache, psychic stimulation, psychotic episodes or convulsions ( rare )

GI -

Anorexia, nasea, vomiting, diarrhea, abdominal cramps

Ophthalmic-

Irreversible retinal damage in patients on long term or high dosage of 4-amino-quinoline, visual disturbances ( blurred vision, difficulty of focusing or accomodation ) nyctaopia, scotomatous vision with field defects of paracentral , pericentral ring types and typically temporal scotomas, eg difficulty reading with words tending to disappear, seeing half an object, misty vision , fog before eyes.

Miscellaneous-

Agranucytosis, pruritus, neutropathy, blood dyscrasias, lichen planus- like eruptions, skin/ mucosal pigment changes, pleomorphic skin eruptions ( prolonged use ) A fewtype of nerve type deafness have occured after prolonged high doses

Hypersensitivity, known or suspected. Resistent P.falciparum infection, porphyria, retinal damage.

Special precautions:

Psoriasis, diseases of haemoatopoietic or CNS systems.

Hepatic impairment. G6PD defeciency.

Pregnancy, irreversible retinopathy can be developed in long term therapy.

Stop treatment if first signs appear.

Regular opthalmological controls necessary.

Epilepsy, children.

Indications:

Prophylaxis and treatment of malaria.

Dosage:

Adults- 300mg (base) weekly, on the same day each week,

Children- administer 5mg base/kg weekly, uptoa maximum of 300kg.

For Availability/supplies 

Lupus erythematosus- systemic

Systemic Lupus erythematous SLE is disease of unknown cause. However, abundant evidence suggests that immunologic mechanisms of tissue injury are important inits pathogenesis. The hall mark of the disease is the presence of number of antibodies to nuclear components, but other imunological abnormalities exist as well.

Some patients with SLE have spontaneous remissions others respoond to corticosteroids and insome patients the course is unresponsive to medications.

Treatment-

A cure to SLE is not available. However, abundant experience indicates that appropriate suppress flare ups and prolong life. Corticosteroids remain the cornerstone of of therapy eventhough -immunosupprssive - drugs seem to help in some patients.

Antimalarials have been used successfullyfor the same synptoms and to control skin eruptions. Chloroquine ghas been used widle in mild SLE but potential renal toxicity has reduced the usage.

Drug induced lupus erythematous-

1. Hydralazine

2. Procainamide

3. Isoniazid

Pharmacology:

Chloroquines exact mechanism of action is not known, but several mechanisms have been suggested. It concentrates in parasitic acid vesicles and raises internal pH. The -(non-weak base effect ) inhibits parasitic growtrh at extrtacellular drug concentrations: this may occur due to active chloroquine-concentrating mechanisms in parasitic acid vesicles.

Another mechanism may involve ferriprotoporphyrin IX aggregates, which are released by parasitized erythrocytes during hemoglobin degradation and serve as chloroquine receptors, causing membrane damage with lysis of parasites or erythrocytes.

Chloroquin may also influence hemoglobin digestion or interfere with parasite/neucleoprotein synthesis.

Pharmacokinetics:

Absorbed readily from GI tract, peak plasma levels are reached in 1 to 6 hrs. Plasm protein binding is 55%. Drug concentration in liver, spleen, kidney., heart, brain, and is strongly bound in melanin- containing cells such as in eyes and skin.

Chloroquine is eliminated very slowly and may persist in tissues for a prolonged period. Up to 70% of a dose may be excreted unchanged in urine and upto 25% as a metabolite.

Renal excretion is enhanced by urinary acidification.

May cause GI upset. Take with food.

Pregnancy:

Use only when clearly needed and when potential benefits outweigh potential hazards to fetus.

Lactation:

Safety for use has not been established: these agents are excreted in breast milk.