Interacting  drugs -

+ Atovaquine

Rifamycins   

 concurrent use with rifampicin results in significant decrease in average steady -state plasma concentrations

Atovaquine +

  TMP+SMZ   

 coadmin decrease steady state con of TMP and SMZ

 Zidovudine  

   concurrent use  decrease in Zidivudine oral clearance leading to 35 % increase in AUC

Diarrhoea 

There were no life-threatening or fatal adverse experiences caused by atovaquone

 Of the patients receiving atovaquone 4% discontinued therapy due to development of rash.

The majority of cases of rash among patients were mild and did not require the discontinuation of dosing.

Development of history of potentailly life-threatening allergic reactions to any of the components of the formulation.

Special precautions-

Absorption- of orally administerd atovaquoneis liimited but can be significantly increased when the drug is taken with food. GI disorders may limit absorption of orally administered drugs.

Patients with these disorders may also acheive plasma concentrations of atovaquone associated within response to therapy in controlled trials.

Concurrent pulmonary conditions- Atovaquone is not effective for concurrent pulmonary conditions such as bacterial, viral or fungal pneumonia or mycobacterial diseases.

Carefully evalute al patients with acute PCP fo other possible causes of pulmonary disease and treat with additional agents as appropiate.

Warnings-

Severe PCP/prophylaxis- clinical experience has been limited to patients with mild to moderate PCP. Atavaquone has not been evaluated as an agent for PCP prophylaxis.

Elderly- excercise caution when treating elderly patients refllecting the greater frequency of decreased hepatic, renal and cardiac function in this population. Pregnancy- use during pregnancy only if the potential benefits justifies the potential risk to fetus.

Lactation- excecise caution when adminstering atovaquone to a nursing woman.

Children- safety and efficacy has not been established

Approved by FDA on November 25, 1992

Indication-

Diarrhoea 

Dosage-

Adults- 750mg administered with food twice daily for 21 days (total daily dose 1500mg). Failure to administer atovaquone with food may result in lower atovaquone plasma concentrations and may limit response to therapy

Missed dose

1. If you miss a dose of this medicine, take it as soon as possible.

2. However, if it is almost time for next dose, skip the missed dose and go back to your regular dosing schedule.

3. Do not double doses.

ATOVAQUONE

1. Stress the importance of taking the prescribed dose.

2. Instruct patients to take their daily doses with meals as the presence of food will significantly improve the absorption of the drug.

3. Allergies- tell your doctor if you ever had any allergic reaction to atovaquone. Also tell your doctor if you are allergic to any food substances, preservatives or dyes.

4.Diet- Make certain that you tell your doctor if you are on any special diet. This medicine must be taken with balanced meals so that it can work properly.

5. Pregnancy- not studied ipregnant women. However studies in rabbits have shown an incr in miscarriages and other harmful effects on the mother and fetus. Before taking this medicine make sure knows your doctor knows if you are pregnant or if you may become prgnant.

6. Breast feeding- not known whether atovaquone passes into breast milk. Be sure you have discussed the risks and benefits of atovaquone with your doctor.

7. Children- has been tested in a limited number of children 1 month of age to 13 years old.

8. Older adults- no specific information available, comparing use of atovaquone in the elderly with use in other age groups.

9. Other medicines- It is importat that your doctor knows ifyuare taking any of the following- Rifampicin- use of rifampicin with atovaquone may decr the amount of atovaquoone in the blood and keep it from working properly.

10. Other medical problems- make sure that you tell your doctor if you have any other medical problems especially- Stomach or intestinal disorders- atovaquone may not work properly in patients with some kind of stomach or intestinal problems

11. Dosing- dosing may be differeet for different patients. Follow your doctors advice and do not change the dose. Keep takng the medicine for the full course of treatment.

12. Missed dose- If you miss a dose of this medicine take it as soon as possible . This will help to keep a constant amount of medicine it the blood. However,if it is almost time for the next dose, skip the dose and go back to normal dosing schedule. Do not double doses.

13. Storage- Keep out of reach of children Store away from heat and direct sunlight Do not store in the bath room , near the kitchen sink,or in other damp places. Heat and moisture may cause the medicine to breakdown. Do not keep outdated medicines or medicines no longer needed. Be sure that all discarded medicines are kept out of reach of children.

Pharmacology

Atovaquone, ananalog of ubiquinone, is an antiprotozoal with anti-pneumocystis activity. The mechanism of action against Pneumocystis carinii pneumonia (PCP) has not been fully elucidated.

Pharmacokinetics

Atovaquone is a highly lipophilic compound with low aqueos solubility. Bioavailability is higly dependent on formulation and diet. The suspension provides an approximately twofold increase in bioavailability in the fasting or fed state.

Administering atovaquine with food enhances its absorption by approximately twofold.

Pregnancy

Use during pregnancy only if the potential benefits justifies the potential risk to fetus.

Lactation

 Excecise caution when adminstering atovaquone to a nursing woman. Children- Safety and efficacy has not been established.