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Anti-HIV Drug Interactions
A Guide to the Interactions Found Between Anti-HIV Drugs and Common HIV-Related Therapies

August 2004

Interactions Table (B-D)

A | E-I | K-P | R | S-Z


Birth control pills
See section on Ethinyl estradiol.

Cidofovir (Vistide) plus ...
Adefovir Should not be used together*. Increases risk of kidney toxicity.
Amikacin Should not be used together*. Increases risk of kidney toxicity.
Amphotericin B Should not be used together*. Increases risk of kidney toxicity.
Foscarnet Should not be used together*. Increases risk of kidney toxicity.
Gentamicin Should not be used together*. Increases risk of kidney toxicity.
Kanamycin Should not be used together*. Increases risk of kidney toxicity.
Pentamidine (IV) Should not be used together*. Increases risk of kidney toxicity.
Probenecid Needs to be taken together to decrease the risk of kidney toxicity.
Streptomycin Should be used together with great caution. Increases risk of kidney toxicity.
Tenofovir Should not be used together*. May increase risk of side effects.
Tobramycin Should not be used together*. Increases risk of kidney toxicity.

Ciprofloxacin (Cipro) plus ...
Antacids Needs to be taken 2 hours before or 6 hours after taking ciprofloxacin, otherwise decreases ciprofloxacin level in blood.
Caffeine May increase caffeine level in blood.
Cyclosporine May increase risk of elevated serum creatinine.
ddI or ddI EC Ciprofloxacin needs to be taken 2 hours before or 6 hours after ddI buffered tablets, otherwise ddI may decrease ciprofloxacin level in blood. Ciprofloxacin may be taken at the same time as ddI EC capsules.
Food May be taken with or without food, but preferred time of dosing is 2 hours after a meal.
Iron supplements Needs to be taken 2 hours before or 6 hours after taking ciprofloxacin, otherwise decreases ciprofloxacin level in blood.
Methotrexate May increase blood level of methotrexate. If used together, check for methotrexate side effects.
Probenecid Increases ciprofloxacin level in blood.
Sucralfate Needs to be taken 2 hours before or 6 hours after taking ciprofloxacin, otherwise decreases ciprofloxacin level in blood.
Theophylline Should not be used together.* Increases risk of serious side effects. If concurrent use cannot be avoided, check theophylline level and adjust dose.
Warfarin May increase warfarin level in blood. Check for warfarin toxicity.
Zinc-containing multivitamins Needs to be taken 2 hours before or 6 hours after taking ciprofloxacin otherwise decreases ciprofloxacin level in blood.

Clarithromycin (Biaxin) plus ...
Alprazolam May increase midazolam blood level. Check for alprazolam side effects.
Amprenavir Increases amprenavir level by 18% in blood. No dose adjustment recommended.
Anticoagulants May increase anticoagulants effect. Check prothrombin (coagulation) time.
Astemizole Should not be used together*. May increase risk of heart problems.
Atazanavir Increases risk of side effects and may decrease clarithromycin effectiveness. Consider alternatives or reduce clarithromycin dose by at least 50%.
Atorvastatin May increase risk of atorvastatin side effects.
AZT Decreases AZT level by 25% in blood. Consider taking at least 2 hours apart.
Carbamazepine Increases carbamazepine level in blood. Check carbamazepine level.
Cisapride Should not be used together*. Increases risk of side effects.
Cyclosporine May increase cyclosporine level in blood.
Delavirdine Interaction is complex. Clarithromycin dose should be adjusted for people with kidney problems.
Digoxin May increase digoxin level in blood. Check digoxin level.
Disopyramide May increase risk of side effects. Check disopyramide level and QTc prolongation.
Efavirenz Slightly increases efavirenz level but decreases clarithromycin level by 39% (increases 14-hydroxy clarithromycin level by 34%) in blood. No dose adjustment currently recommended.
Ergot derivatives Should be used together with caution. May increase risk for serious side effects.
Fluvastatin May increase risk of fluvastatin side effects.
Indinavir Increases clarithromycin level by 53% and indinavir level by 29% in blood. No dose adjustment recommended.
Kaletra Increases clarithromycin level in blood. Clarithromycin dose should be decreased for people with kidney dysfunction.
Loratadine May affect loratidine and clarithromycin levels in blood. No dose adjustment currently recommended.
Lovastatin May increase risk of lovastatin side effects.
Midazolam May increase midazolam blood level. Check for midazolam side effects.
Nevirapine Consider using alternatives to clarithromycin. Decreases clarithromycin level by 30% and increases nevirapine level by 26% in blood.
Pimozide Should not be used together.* Increases risk of serious side effects.
Phenytoin May increase phenytoin level in blood.
Pravastatin May increase risk of pravastatin side effects.
Quinidine May increase risk of side effects. Check quinidine level and QTc prolongation.
Rifabutin Should be used together with caution. May increase rifabutin level and decrease clarithromycin level in blood.
Rifampin Should be used together with caution. May decrease clarithromycin level in blood.
Ritonavir Increases clarithromycin level by 77% and increases ritonavir level by 12% in blood. Requires lower dose of clarithromycin and monitoring for kidney toxicity in people with a history of kidney problems.
Saquinavir (Fortovase) Increases saquinavir level by 177% and increases clarithromycin level by 45% (but decreases 14-hydroxy clarithromycin level by 24%) in blood. No dose adjustments currently recommended.
Sildenafil May increase sildenafil level in blood. Consider dose reduction.
Simvastatin May increase risk of simvastatin side effects.
St. John's Wort Should be used together with great caution. May decrease clarithromycin level in blood.
Tedalafil Should be used together with caution. May increase tedalafil level in blood.
Theophylline Increases theophylline level in blood. Check theophylline level.
Triazolam May increase triazolam level in blood. Check for triazolam side effects.
Trimetrexate May affect trimetrexate and/or clarithromycin level in blood.
Vardenafil Should be used together with caution. May increase vardenafil level in blood.
Warfarin Check prothrombin (coagulation) time.

Clindamycin (Cleocin) plus ...
Erythromycin Should not be used together*. Causes erythromycin and clindamycin to be less effective.
Neuromuscular blocking agents May increase neuromuscular blocking effect.

Clofazimine (Lamprene) plus ...
Dapsone May decrease effectiveness of clofazimine.

Combivir plus ...
Combivir is a single pill containing 2 anti-HIV drugs -- AZT and 3TC. If you take Combivir as part of your regimen, refer separately to drug interactions for AZT and 3TC.

Cycloserine (Seromycin) plus ...
Alcohol May increase risk of seizures.
Ethionamide May increase risk of central nervous system related toxicity.
Isoniazid May increase risk of central nervous system related toxicity.

Dapsone plus ...
Amprenavir May increase dapsone level in blood.
AZT May increase risk of bone marrow toxicity.
Clofazimine May decrease effectiveness of clofazimine.
ddC May increase risk of peripheral neuropathy.
ddI ddI buffered tablets and dapsone need to be taken 2 hours apart, otherwise dapsone has no activity.
Ganciclovir May increase risk of bone marrow toxicity.
Probenecid Should be used together with caution. May increase dapsone level in blood and increase risk of side effects.
Pyrimethamine May increase risk of bone marrow toxicity.
Rifabutin Should be used together with caution. May decrease dapsone level in blood.
Rifampin Should be used together with caution. Decreases dapsone level 7–10 times in blood.
Saquinavir (Invirase) May increase dapsone level in blood. Check for dapsone toxicity.
TMP/SMX Increases trimethoprim level by 1.5 times; increases dapsone level by 1.5 times in blood.

Delavirdine (Rescriptor) plus ...
Alprazolam Should not be used together*. Increases risk of side effects.
Amlodipine Should be used together with caution. May increase amlodipine level in blood. Check for toxicity.
Amphetamines Should be used together with caution. May increase amphetamine level in blood.
Amprenavir May increase amprenavir level in blood. No dose adjustment recommended.
Antacids Needs to be taken 1 hour apart, otherwise decreases delavirdine level by 44% in blood.
Astemizole Should not be used together*. Increases risk of side effects.
Atorvastatin Should be used together with great caution. Use lowest possible dose of atorvastatin. May increase risk of side effects.
Barbiturates May decrease delavirdine level in blood.
Bepridil Should be used together with caution. May increase bepridil level in blood and side effects.
Carbamazepine Should not be used together. May significantly decrease delavirdine level in blood.
Cimetidine Should be used together with caution. May decrease delavirdine level in blood.
Cisapride Should not be used together*. Increases risk of side effects.
Clarithromycin Increases delavirdine level by 31% and increases clarithromycin level by 95% (but decreases 14-hydroxy clarithromycin level by 75%) in blood. Clarithromycin dose should be adjusted for people with kidney problems.
Cyclosporine Should be used together with caution. May increase cyclosporine level in blood. Check cyclosporine level.
ddI or ddI EC Needs to be taken 1 hour apart, otherwise decreases delavirdine level in blood.
Dexamethazone Should be used together with caution. May decrease delavirdine level in blood.
Dihydroergotamine Should not be used together*. Increases risk of side effects.
Diltiazem Should be used together with caution. May increase diltiazem level in blood. Check for toxicity.
Ergonovine Should not be used together*. Increases risk of side effects.
Ergotamine Should not be used together*. Increases risk of side effects.
Erythromycin May increase delavirdine level in blood.
Ethinyl estradiol May increase ethinyl estradiol level in blood. Impact of interaction is uncertain.
Famotidine Should be used together with caution. May decrease delavirdine level in blood.
Felodipine Should be used together with caution. May increase felodipine level in blood. Check for toxicity.
Flecainide Should be used together with caution. Check flecainide level.
Fluoxetine Increases delavirdine level by 50% in blood.
Fluvastatin Should be used together with great caution. Use lowest possible dose of fluvastatin. May increase risk of side effects.
Fosamprenavir Should not be used together. May significantly decrease fosamprenavir level in blood.
Indinavir Increases indinavir level 50–95% in blood. Indinavir may be reduced to 600 mg 3 times a day.
Isradipine Should be used together with caution. May increase isradipine level in blood. Check for toxicity.
Itraconazole May increase delavirdine level in blood.
Kaletra May increase lopinavir level in blood. Needs further study.
Ketoconazole Increases delavirdine level by 50% in blood.
Lansoprazole Should be used together with caution. May decrease delavirdine level in blood.
Lidocaine (systemic) Should be used together with caution. Check lidocaine level.
Loratadine Should be used together with caution. May increase loratadine level in blood.
Lovastatin Should not be used together*. Increases risk of side effects.
Methadone Increases methadone level in blood. May require lower dose of methadone.
Methylergonovine Should not be used together*. Increases risk of side effects.
Midazolam Should not be used together*. Increases risk of side effects.
Nelfinavir Increases nelfinavir level about 95% but decreases nelfinavir active metabolite by about 45%. Decreases delavirdine level by about 40% in blood. No data exist to guide dose adjustments.
Nicardipine Should be used together with caution. May increase nicardipine level in blood. Check for toxicity.
Nifedipine Should be used together with caution. May increase nifedipine level in blood. Check for toxicity.
Nisoldipine Should be used together with caution. May increase nisoldipine level in blood. Check for toxicity.
Nizatidine Should be used together with caution. May decrease delavirdine level in blood.
Omeprazole Should be used together with caution. May decrease delavirdine level in blood.
Phenobarbital Should not be used together. May significantly decrease delavirdine level in blood.
Phenytoin Should not be used together. May significantly decrease delavirdine level in blood.
Pimozide Should not be used together*. Increases risk of side effects.
Propafenone Should be used together with caution. Check propafenone level.
Quinidine Should be used together with caution. Check quinidine level.
Ranitidine Should be used together with caution. May decrease delavirdine level in blood.
Rapamycin Should be used together with caution. May increase rapamycin level in blood. Check rapamycin level.
Rifabutin Should not be used together*. Significantly decreases delavirdine level and increases rifabutin level in blood.
Rifampin Should not be used together*, otherwise significantly decreases delavirdine level in blood.
Ritonavir Increases ritonavir level by about 70% in blood. No dose adjustment currently recommended.
Saquinavir (Fortovase) Increases saquinavir level by 5 times in blood. Decrease saquinavir dose to 800 mg 3 times a day.
Saquinavir (Invirase) Increases saquinavir level by 5 times in blood. May increase risk of gastrointestinal side effects and liver function tests. Decrease saquinavir dose to 800 mg 3 times a day.
Sildenafil Should be used together with caution. Increases sildenafil level in blood. Decrease sildenafil dose to no more than 25 mg in a 48 hour period.
Simvastatin Should not be used together*. Increases risk of side effects.
St. John's Wort Should not be used together. May significantly decrease delavirdine level in blood.
Tacrolimus Should be used together with caution. May increase tacrolimus level in blood. Check tacrolimus level.
Tedalafil Should be used together with caution. May increase tedalafil level in blood.
Triazolam Should not be used together*. Increases risk of side effects.
Vardenafil Should be used together with caution. May increase vardenafil level in blood.
Verapamil Should be used together with caution. May increase verapamil level in blood. Check for toxicity.
Voriconazole Should be used together with caution. May increase delavirdine side effects and decrease effectiveness of voriconazole.
Warfarin Should be used together with caution. Check INR.

Didanosine (ddI, Videx) or ddI EC (Videx EC) plus ...
EC stands for Enteric Coated.
Alcohol Heavy alcohol intake may increase risk of pancreatitis.
Allopurinol Should not be used together. Increases ddI level 113–312% in blood.
Amprenavir Should be taken 2 hours before or 1 hour after taking ddI tablets. ddI EC may be taken at the same time as amprenavir, but only on an empty stomach.
Anticancer drugs May increase risk of peripheral neuropathy.
Atazanavir ddI buffered tablets can significantly decrease atazanavir level in blood. Take atazanavir (with food) either 2 hours before or 1 hour after buffered ddI tablets. Although ddI EC should not affect atazanavir level, they should be taken at least 1 hour apart. Atazanavir should be taken with food and ddI EC should be taken on an empty stomach.
Azithromycin May increase AZT level in blood. No dose adjustment recommended.
Cimetidine Needs to be taken at least 2 hours apart.
Ciprofloxacin Ciprofloxacin needs to be taken 2 hours before or 6 hours after ddI buffered tablets, otherwise ddI may decrease ciprofloxacin level in blood. Ciprofloxacin may be taken at the same time as ddI EC capsules.
d4T Should be used together with great caution. Increases risk of pancreatitis, especially in pregnant women.
Dapsone Needs to be taken 2 hours apart, otherwise dapsone has no activity.
ddC Should not be used together. Significantly increases risk of peripheral neuropathy.
Delavirdine Needs to be taken 1 hour apart, otherwise decreases delavirdine level in blood.
Food Decreases ddI level in blood. ddI and ddI EC should be taken on an empty stomach, at least 2 hours after eating.
Ganciclovir Should be used with caution. Significantly increases ddI level in blood. May increase risk of pancreatitis.
Hydroxyurea Increases anti-HIV activity in test tubes. May increase risk of pancreatitis.
Indinavir May decrease ddI and indinavir levels in blood. Indinavir should be taken 1 hour before or 2 hours after taking ddI.
Itraconazole Needs to be taken 2 hours apart, otherwise ddI buffering agents may significantly decrease itraconazole level in blood.
Kaletra ddI or ddI EC should be taken 1 hour before or 2 hours after taking Kaletra. ddI and ddI EC should be taken on an empty stomach, and Kaletra should be taken with a meal.
Ketoconazole Needs to be taken 2 hours apart, otherwise ddI buffering agents may significantly decrease ketoconazole level in blood.
Methadone Decreases ddI level by 60% in blood.
Nelfinavir Nelfinavir should be taken 2 hours before or after taking ddI or ddI EC. Nelfinavir should be taken with food, and ddI and ddI EC should only be taken on an empty stomach.
Pentamidine (IV) May increase risk of pancreatitis.
Quinolones Quinolones need to be taken 2 hours before or 6 hours after ddI buffered tablets, otherwise ddI may decrease quinolone level in blood. Quinolones may be taken at the same time as ddI EC capsules.
Ribavirin Should not be used together*. Increases risk of pancreatitis and mitochondrial toxicity.
Ritonavir Decreases ddI level by 13% in blood. No dose adjustment recommended, but take 2½ hours apart.
Saquinavir Saquinavir should be taken 2 hours before or after taking ddI or ddI EC. Saquinavir is best taken with food, and ddI and ddI EC should only be taken on an empty stomach.
Tenofovir Should be used together with great caution. Increases ddI level by 44% in blood. May increase risk of ddI side effects.
Tetracyclines Should not be used together*. May increase risk of pancreatitis.


Interpreting Directions

Should not be used together
The risk of side effects from a combination is too high for the two medications to be used together.

An asterisk (*) following this phrase means the side effects may be life-threatening.

Should be used together with caution
The risk of side effects from a combination is possible, but not highly common.

Should be used together with great caution
The risk of side effects from a combination is possible, and though not common may be serious if they occur.


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