Featured White Papers
- Hosted CRM comparison guide (Inside CRM)
- Enterprise PBX buyer's guide (VoIP-News)
- Don't miss this enterprise mobility Webcast! (TechRepublic)
Content provided in partnership with
Health Care Industry
Industry: Email Alert RSS FeedClinically Significant Drug Interactions
American Family Physician, March 15, 2000 by Paul W. Ament, John G. Bertolino, James L. Liszewski
TABLE 1
Overview of Selected Serious Drug Interactions
Interaction Potential effect
Warfarin (Coumadin) plus ciprofloxacin Increased effect of
(Cipro), clarithromycin (Biaxin), warfarin
erythromycin, metronidazole (Flagyl)
or trimethoprim-sulfamethoxazole
(Bactrim, Septra)
Warfarin plus acetaminophen Increased bleeding,
increased INR
Warfarin plus acetylsalicylic acid Increased bleeding,
(aspirin) increased INR
Warfarin plus NSAID Increased bleeding,
increased INR
Fluoroquinolone plus divalent/trivalent Decreased absorption
cations or sucralfate (Carafate) of fluoroquinolone
Carbamazepine (Tegretol) plus Increased
cimetidine (Tagamet), erythromycin, carbamazepine levels
clarithromycin or fluconazole (Diflucan)
Phenytoin (Dilantin) plus cimetidine, Increased phenytoin
erythromycin, clarithromycin or levels
fluconazole
Phenobarbital plus cimetidine, Increased
erythromycin, clarithromycin phenobarbital levels
or fluconazole
Phenytoin plus rifampin (Rifadin) Decreased phenytoin
levels
Phenobarbital plus rifampin Decreased
phenobarbital levels
Carbamazepine plus rifampin Decreased
carbamazepine levels
Lithium plus NSAID or diuretic Increased lithium levels
Oral contraceptive pills plus rifampin Decreased effectiveness
of oral contraception
Oral contraceptive pills plus antibiotics Decreased effectiveness
of oral contraception
Oral contraceptive pills plus Decreased effectiveness
troglitazone (Rezulin) of oral contraception
Cisapride (Propulsid ) plus erythromycin, Prolongation of QT
clarithromycin, fluconazole, interval along with
itraconazole (Sporanox), ketoconazole arrhythmias secondary
(Nizoral), nefazodone (Serzone), to inhibited cisapride
indinavir (Crixivan) or ritonavir (Norvir) metabolism
Cisapride plus class IA or class III Prolongation of QT
antiarrhythmic agents, tricyclic interval along with
antidepressants or phenothiazine arrhythmias
Sildenafil (Viagra) plus nitrates Dramatic hypotension
Sildenafil plus cimetidine, erythromycin, Increased sildenafil levels
itraconazole or ketoconazole
HMG-CoA reductase inhibitor plus Possible rhabdomyolysis
niacin, gemfibrozil (Lopid),
erythromycin or itraconazole
Lovastatin (Mevacor) plus warfarin Increased effect
of warfarin
SSRI plus tricyclic antidepressant Increased tricyclic
antidepressant level
SSRI plus selegiline (Eldepryl) or Hypertensive crisis
nonselective monoamine oxidase
inhibitor
SSRI plus tramadol (Ultram) Increased potential for
seizures; serotonin
syndrome
SSRI plus St. John's wort Serotonin syndrome
SSRI plus naratriptan (Amerge), Serotonin syndrome
rizatriptan (Mazalt), sumatriptan
(Imitrex) or zolmitriptan (Zomig)
Interaction Time to effect
Warfarin (Coumadin) plus ciprofloxacin Generally within
(Cipro), clarithromycin (Biaxin), 1 week
erythromycin, metronidazole (Flagyl)
or trimethoprim-sulfamethoxazole
(Bactrim, Septra)
Warfarin plus acetaminophen Any time
Warfarin plus acetylsalicylic acid Any time
(aspirin)
Warfarin plus NSAID Any time
Fluoroquinolone plus divalent/trivalent Any time
cations or sucralfate (Carafate)
Carbamazepine (Tegretol) plus Generally within
cimetidine (Tagamet), erythromycin, 1 week
clarithromycin or fluconazole (Diflucan)
Phenytoin (Dilantin) plus cimetidine, Generally within
erythromycin, clarithromycin or 1 week
fluconazole
Phenobarbital plus cimetidine, Generally within
erythromycin, clarithromycin 1 week
or fluconazole
Phenytoin plus rifampin (Rifadin) Generally within
1 week
Phenobarbital plus rifampin Generally within
1 week
Carbamazepine plus rifampin Generally within
1 week
Lithium plus NSAID or diuretic Any time
Oral contraceptive pills plus rifampin Any time
Oral contraceptive pills plus antibiotics Any time
Oral contraceptive pills plus Any time
troglitazone (Rezulin)
Cisapride (Propulsid ) plus erythromycin, Generally within
clarithromycin, fluconazole, 1 week
itraconazole (Sporanox), ketoconazole
(Nizoral), nefazodone (Serzone),
indinavir (Crixivan) or ritonavir (Norvir)
Cisapride plus class IA or class III Any time
antiarrhythmic agents, tricyclic
antidepressants or phenothiazine
Sildenafil (Viagra) plus nitrates Soon after taking
sildenafil
Sildenafil plus cimetidine, erythromycin, Any time
itraconazole or ketoconazole
HMG-CoA reductase inhibitor plus Any time
niacin, gemfibrozil (Lopid),
erythromycin or itraconazole
Lovastatin (Mevacor) plus warfarin Any time
SSRI plus tricyclic antidepressant Any time
SSRI plus selegiline (Eldepryl) or Soon after
nonselective monoamine oxidase initiation
inhibitor
SSRI plus tramadol (Ultram) Any time
SSRI plus St. John's wort Any time
SSRI plus naratriptan (Amerge), Possibly after
rizatriptan (Mazalt), sumatriptan initial dose
(Imitrex) or zolmitriptan (Zomig)
Interaction Recommendations and comments
Warfarin (Coumadin) plus ciprofloxacin Select alternative antibiotic.
(Cipro), clarithromycin (Biaxin),
erythromycin, metronidazole (Flagyl)
or trimethoprim-sulfamethoxazole
(Bactrim, Septra)
Warfarin plus acetaminophen Use lowest possible
acetaminophen dosage
and monitor INR.
Warfarin plus acetylsalicylic acid Limit aspirin dosage to 100
(aspirin) mg per day and monitor INR.
Warfarin plus NSAID Avoid concomitant use if
possible; if coadministration
is necessary, use a
cyclooxygenase-2 inhibitor
and monitor INR.
Fluoroquinolone plus divalent/trivalent Space administration by 2
cations or sucralfate (Carafate) to 4 hours.
Carbamazepine (Tegretol) plus Monitor carbamazepine levels.
cimetidine (Tagamet), erythromycin,
clarithromycin or fluconazole (Diflucan)
Phenytoin (Dilantin) plus cimetidine, Monitor phenytoin levels.
erythromycin, clarithromycin or
fluconazole
Phenobarbital plus cimetidine, Clinical significance has
erythromycin, clarithromycin not been established.
or fluconazole Monitor phenobarbital levels.
Phenytoin plus rifampin (Rifadin) Clinical significance has
not been established.
Monitor phenytoin levels.
Phenobarbital plus rifampin Monitor phenobarbital levels.
Carbamazepine plus rifampin Clinical significance has
not been established.
Monitor carbamazepine levels.
Lithium plus NSAID or diuretic Decrease lithium dosage by
50% and monitor lithium
levels.
Oral contraceptive pills plus rifampin Avoid if possible. If
combination therapy is
necessary, have the patient
take an oral contraceptive
pill with a higher
estrogen content
([greater than] 35 [micro] g
of ethinyl estradiol) or
recommend alternative method
of contraception.
Oral contraceptive pills plus antibiotics Avoid if possible. If
combination therapy is
necessary, recommend use of
alternative contraceptive
method during cycle.
Oral contraceptive pills plus Have the patient take an oral
troglitazone (Rezulin) contraceptive pill with a
higher estrogen content or
recommend alternative
method of contraception.
Cisapride (Propulsid ) plus erythromycin, Avoid. Consider whether
clarithromycin, fluconazole, metoclopromide (Reglan)
itraconazole (Sporanox), ketoconazole therapy is appropriate for
(Nizoral), nefazodone (Serzone), the patient.
indinavir (Crixivan) or ritonavir (Norvir)
Cisapride plus class IA or class III Avoid. Consider whether
metoclopromide therapy is
antiarrhythmic agents, tricyclic appropriate for the patient.
antidepressants or phenothiazine
Sildenafil (Viagra) plus nitrates Absolute contraindication.
Sildenafil plus cimetidine, erythromycin, Initiate sildenafil at a
itraconazole or ketoconazole 25-mg dose.
HMG-CoA reductase inhibitor plus Avoid if possible. If
combination therapy is
niacin, gemfibrozil (Lopid), necessary, monitor the
erythromycin or itraconazole patient for toxicity.
Lovastatin (Mevacor) plus warfarin Monitor INR.
SSRI plus tricyclic antidepressant Monitor for anticholinergic
excess and consider
lower dosage of tricyclic
antidepressant.
SSRI plus selegiline (Eldepryl) or Avoid.
nonselective monoamine oxidase
inhibitor
SSRI plus tramadol (Ultram) Monitor the patient for
signs and symptoms
of serotonin syndrome.
SSRI plus St. John's wort Avoid.
SSRI plus naratriptan (Amerge), Avoid if possible. If
rizatriptan (Mazalt), sumatriptan combination therapy is
(Imitrex) or zolmitriptan (Zomig) necessary, monitor the
patient for signs and
symptoms of serotonin
syndrome.
INR = International Normalized Ratio; NSAID = nonsteroidal
anti-inflammatory drug; HMG-CoA = 3-hydroxy-3-methylglutaryl-coenzyme A
reductase inhibitor; SSRI = selective serotonin reuptake inhibitor.
TABLE 2
Common Products Containing Divalent or Trivalent Cations
Cations Products
Aluminum Alu-Cap, AlternaGel, Amphojel, Basaljel
Aluminum and magnesium Gelusil, Maalox, Mylanta, Riopan
combinations
Calcium Caltrate, Citracal, Os-Cal, PhosLo, Titralac, Tums
Iron Feosol, Fergon, Niferex, Nu-Iron, Slow Fe
Magnesium Almora, Citrate of Magnesia, Mag-Ox 400,
Milk of Magnesia, Slow-Mag, Uro-Mag
TABLE 3
Agents That Inhibit or Are Metabolized
Through Cytochrome P450 Pathways[*]
Pathway Inhibitors Substrates
Cytochrome Fluoxetine (Prozac) Codeine
P450 2D6 Paroxetine (Paxil) Metoprolol (Lopressor, Toprol XL)
Sertraline (Zoloft) Paroxetine
Perphenazine (Trilafon)
Sertraline
Venlafaxine (Effexor)
Cytochrome Cimetidine (Tagamet) Cisapride (Propulsid)
P450 3A4 Clarithromycin (Biaxin) Erythromycin
Erythromycin
Fluvoxamine (Luvox)
Grapefruit juice
Itraconazole (Sporanox)
Ketoconazole (Nizoral)
Lovastatin (Mevacor)
Nefazodone (Serzone)
[*]--Combining an agent that inhibits cytochrome P450 metabolism with
a substrate of cytochrome P450 may potentiate the pharmacologic
effects of the substrate through inhibition of hepatic metabolism.
TABLE 4
Selected Sources of Information on Drug Interactions
Clinical Pharmacology (CD-ROM, Internet)
Complete database for drug interactions as well as clinically useful drug
information; updated quarterly.
Gold Standard Multimedia
Product Ordering
320 W. Kennedy Blvd., Suite 400
Tampa, FL 33606
Telephone: 800-375-0943, 813-258-4747
Fax: 813-259-1585
E-mail: sales@gsm.com
Hansten and Horn's Drug Interactions Analysis and Management (manual)
Easy-to-use index that categorizes a drug interaction by clinical
significance, along with a concise reference monograph discussing
the interaction; updated quarterly.
Applied Therapeutics, Inc.
Box 5077
Vancouver, WA 98668
Telephone: 360-253-7123
Fax: 360-253-8475
Handbook of Adverse Drug Interactions (manual); Adverse Drug
Interactions Program (software, Internet)
Software searches for interactions between two and up to 25 drugs.
The Medical Letter on Drugs and Therapeutics
1000 Main St.
New Rochelle, NY 10801-7537
Telephone: 800-211-2769, 914-235-0500
Fax: 914-632-1733
E-mail: custserv@themedicalletter.org
Drug Interactions Analysis and Management (loose-leaf or bound manual);
Drug Interaction Facts (loose-leaf or bound manual with software)
Information about drug-drug and drug-food interactions in a quick reference
format, along with descriptive monographs of drug interactions selected on
the basis of their potential to alter patient outcomes; updated quarterly.
Facts and Comparisons
111 West Port Plaza, Suite 300
St. Louis, MO 63146
Telephone: 800-223-0554, 314-223-0554
Fax: 314-878-5563
E-mail: networksales@drugfacts.com, or service@drugfacts.com
COPYRIGHT 2000 American Academy of Family Physicians
COPYRIGHT 2000 Gale Group
Find Research Guides for:
Find Featured Titles for: News
Most Popular Articles in Health
- Fuel your workout: exercisers who eat before they work out have more energy ...
- Soothe a dry, itchy scalp: 5 easy expert solutions
- Cocktails and calories: Beer, wine and liquor calories can really add up. ...
- The sour truth about apple cider vinegar - evaluation of therapeutic use
- The, six best supplements you've never heard of: these secret weapons can ...
- More »