Not all drug interactions are harmful. Certain drugs can actually increase the potency of others. AZT, for example, has been shown to increase the potency of ddI.
In this issue's article, however, adverse reactions associated with certain drug combinations will be examined.
Many examples in the tables accompanying this article (see below) point to an increase in liver toxicity and peripheral neuropathy, bone marrow suppression and risk of pancreatitis with certain combinations. In particular, antacids and antiulcer agents have a tendency to decrease the levels of certain medications. Antibiotics in combination have a tendency to either suppress the bone marrow, increase liver toxicity, or decrease the efficacy of some of these drugs, while it is extremely important to consider how certain antivirals combine together. Finally, ingesting alcohol can increase one's risk of pancreatitis, especially when taken with ddI and other medications that are associated with such a risk.
These tables detail some potential interactions associated with various antiretrovirals. They are by no means complete listings, nor are they meant to suggest that all of these interactions will have some clinical significance with each individual. The tables are meant to initiate conversations between you and your care providers.
Not every interaction was elaborated upon in the Comment column, yet they should still be areas of concern to discuss with your care provider. Sometimes a dosage adjustment or discontinuation of a specific therapy can alleviate the potential of certain interactions.
|
Non-nucleoside reverse transcriptase inhibitors
|
|
Drug Interaction Concerns with Rescriptor (delavirdine mesylate)
|
Drug
Class |
Generic
Name |
Brand
Name |
Potential
for: |
Comments |
| Antacids | | Maalox, Mylanta, Rolaids, etc. | Decreased absorption of Rescriptor | Take at least 2 hours apart |
| Antiseizure |
Carbamazepine | Tegretol | Decreased Rescriptor levels |
|
| Phenytoin | Dilantin | Decreased Rescriptor levels |
| Antiulcer agent | Cimetidine | Tagamet | Decreased Rescriptor levels | Take at least 2 hours apart |
| Ranitidine | Zantac | Decreased Rescriptor levels | Take at least 2 hours apart |
| Antiviral | didanosine, ddI | Videx | Decreased antiviral activity | Take 1 hour apart |
| Antibiotic |
Rifabutin | Mycobutin | Decreased Rescriptor levels | Avoid using together |
| Rifampin | Rifadin | Decreased Rescriptor levels | Avoid using together |
Drug Interaction Concerns with Viramune (nevirapine)
|
Drug
Class |
Generic
Name |
Brand
Name |
Potential
for: |
Comments |
| Antibiotic | Amoxicillin | Amoxil | Increased risk of skin rashes and Stephen-
Johnson syndrome |
Potentially life-threatening. Discontinue use and seek medical care. |
| Clarithromycin | Biaxin | Increased risk of liver toxicity | |
| Erythromycin | Erycette | Increased risk of liver toxicity |
| Rifabutin | Mycobutin | Decreased Viramune levels |
| Rifampin | Rifadin | Decreased Viramune levels |
| Antiulcer agent | Cimetidine | Tagamet | Decreased Viramune levels | |
| Ranitidine | Zantac | Decreased Viramune levels |
| Antiseizure | Phenytoin | Dilantin | Decreased Viramune levels | |
|
Nucleoside analogues |
|
Drug Interaction Concerns with Retrovir (Zidovudine, AZT) |
Drug
Class |
Generic
Name |
Brand
Name |
Potential
for: |
Comments |
| Antifungal | Amphotericin B | Fungizone | Bone Marrow Damage |
|
| Flucytosine | Ancobon | Bone Marrow Damage |
| Antibiotic |
Trimethoprim /
Sulfamethoxazole | Bactrim |
Bone Marrow Damage -- Decreased red blood cells and neutrophils | Monitor for anemia and neutropenia. May require supportive G-CSF therapy. |
| Clarithromycin | Biaxin | Reduced AZT levels | May need to adjust AZT dose |
| Dapsone | Dapsone USP | Bone Marrow Damage | Monitor for anemia and neutropenia. May require supportive G-CSF therapy. |
| Rifampin | Rifadin | Decreased antiviral activity | May need to adjust AZT dose |
| Antiviral |
Stavudine, d4T | Zerit | Decreased antiviral activity | Not recommended by DHHS Guidelines |
| Cytovene | Ganciclovir | Decreased neutrophils | May require supportive G-CSF therapy |
| zalcitabine, ddC | HIVID | Increased risk of pancreatitis | Monitor amylase and lipase |
| Antiprotozoal | Pentamidine | Pentam 300 | Bone Marrow Damage | Monitor for anemia and neutropenia. May require supportive G-CSF therapy. |
| Pyrimethamine + Sulfadiazine | Daraprim + Sulfadiazine | Bone Marrow Damage | Monitor for anemia and neutropenia. May require supportive G-CSF therapy. |
Drug Interaction Concerns with Videx (didanosine, ddI) |
Drug
Class |
Generic
Name |
Brand
Name |
Potential
for: |
Comments |
| Antiulcer agent | Cimetidine | Tagamet | Decreased absorption | Take 2 hours apart |
| Antibiotic | Dapsone | Dapsone USP | Increased peripheral neuropathy. Decreased dapsone absportion. | Take 2 hours apart to avoid absorption concerns |
| Antiviral | zalcitabine, ddC | Hivid | Increased peripheral neuropathy and risk of pancreatitis | Monitor amylase and lipase |
| delaviridine mesylate | Rescriptor | Decreased antiviral activity | Take 1 hour apart |
| Ganciclovir | Cytovene | Reduced ganciclovir levels and increased risk of pancreatitis | |
| Antifungal | Ketoconazole | Nizoral | Reduced ketoconazole activity | Use alternative antifungal or take 2 hours apart |
| Antiprotozoal | Pentamidine | Pentam 300 | Increased risk of pancreatitis | Monitor amylase and lipase |
Drug Interaction Concerns with HIVID (zalcitabine, ddC) |
Drug
Class |
Generic
Name |
Brand
Name |
Potential
for: |
Comments |
| Antiviral | zidovudine, AZT | Retrovir | Increased risk of pancreatitis | Monitor amylase and lipase |
| Antiulcer agent | Cimetidine | Tagamet | Decreased ddC levels | |
| Antacids | | Maalox, Mylanta, Rolaids, etc. | Decreased ddC levels | |
| Antiprotozoal | Pentamidine | Pentam 300 | Increased risk of peripheral neuropathy and pancreatitis | Monitor amylase and lipase for pancreatitis |
Drug Interaction Concerns with Zerit (stavudine, d4T) |
Drug
Class |
Generic
Name |
Brand
Name |
Potential
for: |
Comments |
| Antiviral | zidovudine, AZT | Retrovir | Decreased antiviral activity | Not recommended by DHHS Guidelines |
| Ganciclovir | Cytovene | Increased risk of pancreatitis | Monitor amylase and lipase |
| Antiprotozoal | Pentamidine | Pentam 300 | Increased risk of pancreatitis | Monitor amylase and lipase |
Drug Interaction Concerns with Epivir (lamivudine, 3TC) |
Drug
Class |
Generic
Name |
Brand
Name |
Potential
for: |
Comments |
| Antiulcer agent | Cimetidine | Tagamet | Decreased levels of Epivir and/or Cimetidine | May need to adjust dosage of either Epivir or Tagamet |
| Ranitidine | Zantac | Decreased levels of Epivir and/or Ranitidine | |
| Antibiotic | Ethambutol | Myambutol | Decreased levels of Epivir and/or Ethambutol | |
Additionally, the following drugs may increase the risk of peripheral neuropathy when taken with HIVID (ddC): Aminoglycosides, Amphotericin B, Antineoplastics, Chloramphenicol, Cisplatin, Dapsone, Disulfiram (Antabase), Foscarnet, Ethionamide, Hydralazine, Iodoquinol, Isoniazid, Metronidazole, Pentamidine, Phenytoin, Probenecid, and Ribavirin. This same list may also to apply to Videx (ddI) and Zerit (d4T), and peripheral neuropathy may also increase when the three drugs (ddC, ddI, and d4T) are used in combinations together. Also, use of Retrovir (AZT) and Pentamidine when taken with HIVID (ddC) may increase the risk of pancreatitis.
Glenn Gaylord is a Treatment Advocate with AIDS Project Los Angeles. He can be reached via e-mail: ggaylord@apla.org or by calling (213) 993-1509.
.
