| Antibiotics |
| Antibiotics |
Oral contraceptives (birth control pills [BCPs]) |
Contraception |
Decreased effectiveness of oral contraceptives has been suggested for several antibiotic classes because of the potential for lowering plasma levels of the contraceptive drug. However, most well-designed studies do not show any reduction in estrogen serum levels in patients taking antibiotics (except rifampin). |
| RECOMMENDATION: Okay to use dental antibiotics. Provide advice to patient about potential risk and for consideration of additional contraceptive measures. |
| Beta-lactams (penicillins, cephalosporins) |
Allopurinol (Lopurin, Zyloprim) |
Gout |
Incidence of minor allergic reactions to ampicillin is increased. Other penicillins have not been implicated. |
| RECOMMENDATION: Avoid ampicillin. |
| Beta blockers (e.g., Tenormin, Lopressor, Inderal, Corgard) |
Hypertension |
Serum levels of atenolol are reduced after prolonged use of ampicillin. Anaphylactic reactions to penicillins or other drugs may be more severe in patients taking beta blockers because of increased mediator release from mast cells. |
| RECOMMENDATION: Use ampicillin cautiously, advise patient of potential reaction. |
| Tetracyclines and other bacteriostatic antibiotics |
Infection, acne, or periodontal disease |
Effectiveness of penicillins and cephalosporins may be reduced by bacteriostatic agents. |
| RECOMMENDATION: Avoid interaction. |
| Tetracyclines Fluoroquinolones |
Antacids |
Dyspepsia, gastroesophageal reflux, peptic ulcer |
Antacids, dairy products, and other agents containing divalent (calcium, iron) and trivalent cations will chelate these antibiotics and limit their absorption. Doxycycline is least influenced by this interaction. |
| RECOMMENDATION: Avoid interaction. |
| Insulin |
Diabetes mellitus |
Doxycycline and oxytetracycline have been documented as enhancing the hypoglycemic effects of exogenously administered insulin. |
| RECOMMENDATION: Select a different antibiotic, or increase carbohydrate intake. |
| Doxycycline |
Methotrexate |
Immunosuppression |
In patients taking high-dose methotrexate, interaction can lead to increased methotrexate concentrations, making toxicity likely. |
| RECOMMENDATION: Select different antibiotic. |
| Metronidazole |
Ethanol |
Alcohol use or abuse |
Severe disulfiram-like reactions are well documented. |
| RECOMMENDATION: Avoid interaction. |
| Lithium |
Manic depression |
Inhibits renal excretion of lithium, leading to elevated/toxic levels of lithium. Lithium toxicity produces confusion, ataxia, and kidney damage. |
| RECOMMENDATION: Avoid interaction. |
| Antibiotics/antifungals metabolized by CYP3A4 and CYP1A2 (e.g., macrolide antibiotics [erythromycin, clarithromycin], antifungals [ketoconazole, fluconazole, itraconazole]) |
Benzodiazepines |
Anxiety |
Delayed metabolism of benzodiazepine, increasing the pharmacologic effects, can result in excessive sedation and irrational behavior. |
| RECOMMENDATION: Reduce dose of benzodiazepine or avoid interaction. |
| Buspirone |
Depression |
Delayed metabolism of buspirone, increasing pharmacologic effect. |
| RECOMMENDATION: Avoid interaction. |
| Carbamazepine (Tegretol) |
Seizure disorder |
Increased blood levels of carbamazepine, leading to toxicity; symptoms include drowsiness, dizziness, nausea, headache, and blurred vision. Hospitalization has been required. |
| RECOMMENDATION: Avoid interaction. |
| Cisapride |
Gastroesophageal reflux |
Delayed metabolism of cisapride, increasing the pharmacologic effects and risk for cardiac arrhythmia and sudden death. |
| RECOMMENDATION: Avoid interaction. |
| Cyclosporine |
Organ transplantation |
Enhanced immunosuppression and nephrotoxicity. |
| RECOMMENDATION: Avoid interaction. |
| Disopyramide, Quinidine |
Cardiac arrhythmias |
Inhibits CYP3A4 metabolism, resulting in large increases in antiarrhythmia drug that can lead to arrhythmias. |
| RECOMMENDATION: Avoid interaction. |
| Lovastatin, pravastatin, simastatin, and other statins |
Hyperlipidemia |
Increases plasma concentration of statin drugs—may result in muscle (eosinophilia) myalgia and rhabdomyolysis (muscle breakdown and pain) and acute renal failure. |
| RECOMMENDATION: Avoid interaction. |
| Pimozide |
Antipsychotic, used to control motor tics |
May result in increased concentrations of pimozide and possibly prolongation of the QT interval. |
| RECOMMENDATION: Avoid interaction. |
| Prednisone, methylprednisolone |
Autoimmune disorders, organ transplantation |
Increased risk of Cushing’s syndrome and immunosuppression |
| RECOMMENDATION: Monitor patient, and shorten duration of antibiotic administration if possible. |
| Theophylline (Theodur) |
Asthma |
Erythromycins inhibit the metabolism of theophylline, leading to toxic serum levels (symptoms of toxicity: headache, nausea, vomiting, confusion, thirst, cardiac arrhythmias, and convulsions). Conversely, theophylline reduces serum levels of erythromycin. |
| RECOMMENDATION: Avoid prescribing erythromycin. |
| Antibiotics (especially erythromycin, clarithromycin, and tetracycline) |
Digoxin (Lanoxin) |
Congestive heart failure |
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