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Drug Interactions between amlodipine and diltiazem

This report displays the potential drug interactions for the following 2 drugs:

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Interactions between your drugs

Moderate

dilTIAZem amLODIPine

Applies to: diltiazem and amlodipine

MONITOR: Coadministration with CYP450 3A4 inhibitors may increase the plasma concentrations of amlodipine, which is a substrate of the isoenzyme. In 8 elderly hypertensive patients, administration of a single 5 mg dose of amlodipine in combination with the moderate CYP450 3A4 inhibitor diltiazem (180 mg orally daily for 3 days) resulted in a nearly 60% increase in amlodipine peak plasma concentration (Cmax) and systemic exposure (AUC). Associated systolic, diastolic, and standing blood pressures decreased compared to those obtained with amlodipine alone. Erythromycin, another moderate inhibitor, did not significantly alter amlodipine systemic exposure in healthy volunteers. However, pharmacokinetic changes may be more pronounced in elderly patients.

MANAGEMENT: Close monitoring of clinical response and tolerance is recommended if amlodipine is prescribed with potent or moderate CYP450 3A4 inhibitors. Dosage reduction may be required for amlodipine. Patients should be advised to seek medical attention if they experience edema or swelling of the lower extremities; sudden, unexplained weight gain; difficulty breathing; chest pain or tightness; or hypotension as indicated by dizziness, fainting, or orthostasis.

References

  1. "Product Information. Norvasc (amlodipine)." Pfizer U.S. Pharmaceuticals PROD (2002):
  2. Sasaki M, Maeda A, Fujimura A "Influence of diltiazem on the pharmacokinetics of amlodipine in elderly hypertensive patients." Eur J Clin Pharmacol 57 (2001): 85-6
  3. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0
  4. Canadian Pharmacists Association "e-CPS. http://www.pharmacists.ca/function/Subscriptions/ecps.cfm?link=eCPS_quikLink" (2006):
  5. Cerner Multum, Inc. "Australian Product Information." O 0
View all 5 references

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Drug and food interactions

Moderate

dilTIAZem food

Applies to: diltiazem

MONITOR: Like many CNS-active agents, alcohol can exhibit hypotensive effects. Coadministration with antihypertensive agents including diltiazem may result in additive effects on blood pressure and orthostasis.

MONITOR: Grapefruit juice may increase the plasma concentrations of orally administered diltiazem in some patients. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruit. In a study of ten healthy male volunteers, administration of a single 120 mg oral dose of immediate-release diltiazem in combination with 250 mL of grapefruit juice increased the diltiazem peak plasma concentration (Cmax) and systemic exposure (AUC) by an average of 22% and 20%, respectively, compared to administration with water. The time to reach Cmax (Tmax) and the terminal half-life were not affected, and no statistically significant differences in blood pressure and heart rate were observed during administration with grapefruit juice relative to water. In a different study, repeated administration of 200 mL of grapefruit juice at 0, 2, 4, 8 and 12 hours had no significant effect on the Cmax or AUC of a single 120 mg oral dose of diltiazem, but increased its half-life from 4.1 to 5.1 hours. The ratios for the N-demethyl and deacetyl metabolites to diltiazem were also not affected by grapefruit juice. However, because pharmacokinetic interactions involving grapefruit juice are often subject to a high degree of interpatient variability, the extent to which a given patient may be affected is difficult to predict.

MANAGEMENT: Patients should be advised that alcohol may potentiate the hypotensive effects of diltiazem, especially during the initiation of therapy and following a dosage increase. Caution should be exercised when rising from a sitting or recumbent position, and patients should notify their physician if they experience dizziness, lightheadedness, syncope, orthostasis, or tachycardia. Patients who regularly consume grapefruit or grapefruit juice should be monitored for increased adverse effects of diltiazem such as such as headache, irregular heartbeat, edema, unexplained weight gain, and chest pain. Grapefruit and grapefruit juice should be avoided if an interaction is suspected.

References

  1. Bailey DG, Arnold JMO, Spence JD "Grapefruit juice and drugs - how significant is the interaction." Clin Pharmacokinet 26 (1994): 91-8
  2. Sigusch H, Henschel L, Kraul H, Merkel U, Hoffmann A "Lack of effect of grapefruit juice on diltiazem bioavailability in normal subjects." Pharmazie 49 (1994): 675-9
  3. Bailey DG, Malcolm J, Arnold O, Spence JD "Grapefruit juice-drug interactions." Br J Clin Pharmacol 46 (1998): 101-10
  4. Christensen H, Asberg A, Holmboe AB, Berg KJ "Coadministration of grapefruit juice increases systemic exposure of diltiazem in healthy volunteers." Eur J Clin Pharmacol 58 (2002): 515-520
  5. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0
View all 5 references

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Moderate

amLODIPine food

Applies to: amlodipine

MONITOR: Many psychotherapeutic and CNS-active agents (e.g., anxiolytics, sedatives, hypnotics, antidepressants, antipsychotics, opioids, alcohol, muscle relaxants) exhibit hypotensive effects, especially during initiation of therapy and dose escalation. Coadministration with antihypertensives and other hypotensive agents, in particular vasodilators and alpha-blockers, may result in additive effects on blood pressure and orthostasis.

MANAGEMENT: Caution and close monitoring for development of hypotension is advised during coadministration of these agents. Some authorities recommend avoiding alcohol in patients receiving vasodilating antihypertensive drugs. Patients should be advised to avoid rising abruptly from a sitting or recumbent position and to notify their physician if they experience dizziness, lightheadedness, syncope, orthostasis, or tachycardia.

References

  1. Sternbach H "Fluoxetine-associated potentiation of calcium-channel blockers." J Clin Psychopharmacol 11 (1991): 390-1
  2. Shook TL, Kirshenbaum JM, Hundley RF, Shorey JM, Lamas GA "Ethanol intoxication complicating intravenous nitroglycerin therapy." Ann Intern Med 101 (1984): 498-9
  3. Feder R "Bradycardia and syncope induced by fluoxetine." J Clin Psychiatry 52 (1991): 139
  4. Ellison JM, Milofsky JE, Ely E "Fluoxetine-induced bradycardia and syncope in two patients." J Clin Psychiatry 51 (1990): 385-6
  5. Rodriguez de la Torre B, Dreher J, Malevany I, et al. "Serum levels and cardiovascular effects of tricyclic antidepressants and selective serotonin reuptake inhibitors in depressed patients." Ther Drug Monit 23 (2001): 435-40
  6. Cerner Multum, Inc. "Australian Product Information." O 0
  7. Pacher P, Kecskemeti V "Cardiovascular side effects of new antidepressants and antipsychotics: new drugs, old concerns?" Curr Pharm Des 10 (2004): 2463-75
  8. Andrews C, Pinner G "Postural hypotension induced by paroxetine." BMJ 316 (1998): 595
View all 8 references

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Moderate

dilTIAZem food

Applies to: diltiazem

MONITOR: Calcium-containing products may decrease the effectiveness of calcium channel blockers by saturating calcium channels with calcium. Calcium chloride has been used to manage acute severe verapamil toxicity.

MANAGEMENT: Management consists of monitoring the effectiveness of calcium channel blocker therapy during coadministration with calcium products.

References

  1. Henry M, Kay MM, Viccellio P "Cardiogenic shock associated with calcium-channel and beta blockers: reversal with intravenous calcium chloride." Am J Emerg Med 3 (1985): 334-6
  2. Moller IW "Cardiac arrest following intravenous verapamil combined with halothane anaesthesia." Br J Anaesth 59 (1987): 522-6
  3. Oszko MA, Klutman NE "Use of calcium salts during cardiopulmonary resuscitation for reversing verapamil-associated hypotension." Clin Pharm 6 (1987): 448-9
  4. Schoen MD, Parker RB, Hoon TJ, et al. "Evaluation of the pharmacokinetics and electrocardiographic effects of intravenous verapamil with intravenous calcium chloride pretreatment in normal subjects." Am J Cardiol 67 (1991): 300-4
  5. O'Quinn SV, Wohns DH, Clarke S, Koch G, Patterson JH, Adams KF "Influence of calcium on the hemodynamic and anti-ischemic effects of nifedipine observed during treadmill exercise testing." Pharmacotherapy 10 (1990): 247
  6. Woie L, Storstein L "Successful treatment of suicidal verapamil poisoning with calcium gluconate." Eur Heart J 2 (1981): 239-42
  7. Morris DL, Goldschlager N "Calcium infusion for reversal of adverse effects of intravenous verapamil." JAMA 249 (1983): 3212-3
  8. Guadagnino V, Greengart A, Hollander G, Solar M, Shani J, Lichstein E "Treatment of severe left ventricular dysfunction with calcium chloride in patients receiving verapamil." J Clin Pharmacol 27 (1987): 407-9
  9. Luscher TF, Noll G, Sturmer T, Huser B, Wenk M "Calcium gluconate in severe verapamil intoxication." N Engl J Med 330 (1994): 718-20
  10. Bar-Or D, Gasiel Y "Calcium and calciferol antagonise effect of verapamil in atrial fibrillation." Br Med J (Clin Res Ed) 282 (1981): 1585-6
  11. Lipman J, Jardine I, Roos C, Dreosti L "Intravenous calcium chloride as an antidote to verapamil-induced hypotension." Intensive Care Med 8 (1982): 55-7
  12. McMillan R "Management of acute severe verapamil intoxication." J Emerg Med 6 (1988): 193-6
  13. Perkins CM "Serious verapamil poisoning: treatment with intravenous calcium gluconate." Br Med J 2 (1978): 1127
  14. Moroni F, Mannaioni PF, Dolara A, Ciaccheri M "Calcium gluconate and hypertonic sodium chloride in a case of massive verapamil poisoning." Clin Toxicol 17 (1980): 395-400
View all 14 references

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Moderate

amLODIPine food

Applies to: amlodipine

MONITOR: Calcium-containing products may decrease the effectiveness of calcium channel blockers by saturating calcium channels with calcium. Calcium chloride has been used to manage acute severe verapamil toxicity.

MANAGEMENT: Management consists of monitoring the effectiveness of calcium channel blocker therapy during coadministration with calcium products.

References

  1. Henry M, Kay MM, Viccellio P "Cardiogenic shock associated with calcium-channel and beta blockers: reversal with intravenous calcium chloride." Am J Emerg Med 3 (1985): 334-6
  2. Moller IW "Cardiac arrest following intravenous verapamil combined with halothane anaesthesia." Br J Anaesth 59 (1987): 522-6
  3. Oszko MA, Klutman NE "Use of calcium salts during cardiopulmonary resuscitation for reversing verapamil-associated hypotension." Clin Pharm 6 (1987): 448-9
  4. Schoen MD, Parker RB, Hoon TJ, et al. "Evaluation of the pharmacokinetics and electrocardiographic effects of intravenous verapamil with intravenous calcium chloride pretreatment in normal subjects." Am J Cardiol 67 (1991): 300-4
  5. O'Quinn SV, Wohns DH, Clarke S, Koch G, Patterson JH, Adams KF "Influence of calcium on the hemodynamic and anti-ischemic effects of nifedipine observed during treadmill exercise testing." Pharmacotherapy 10 (1990): 247
  6. Woie L, Storstein L "Successful treatment of suicidal verapamil poisoning with calcium gluconate." Eur Heart J 2 (1981): 239-42
  7. Morris DL, Goldschlager N "Calcium infusion for reversal of adverse effects of intravenous verapamil." JAMA 249 (1983): 3212-3
  8. Guadagnino V, Greengart A, Hollander G, Solar M, Shani J, Lichstein E "Treatment of severe left ventricular dysfunction with calcium chloride in patients receiving verapamil." J Clin Pharmacol 27 (1987): 407-9
  9. Luscher TF, Noll G, Sturmer T, Huser B, Wenk M "Calcium gluconate in severe verapamil intoxication." N Engl J Med 330 (1994): 718-20
  10. Bar-Or D, Gasiel Y "Calcium and calciferol antagonise effect of verapamil in atrial fibrillation." Br Med J (Clin Res Ed) 282 (1981): 1585-6
  11. Lipman J, Jardine I, Roos C, Dreosti L "Intravenous calcium chloride as an antidote to verapamil-induced hypotension." Intensive Care Med 8 (1982): 55-7
  12. McMillan R "Management of acute severe verapamil intoxication." J Emerg Med 6 (1988): 193-6
  13. Perkins CM "Serious verapamil poisoning: treatment with intravenous calcium gluconate." Br Med J 2 (1978): 1127
  14. Moroni F, Mannaioni PF, Dolara A, Ciaccheri M "Calcium gluconate and hypertonic sodium chloride in a case of massive verapamil poisoning." Clin Toxicol 17 (1980): 395-400
View all 14 references

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Minor

amLODIPine food

Applies to: amlodipine

The consumption of grapefruit juice may slightly increase plasma concentrations of amlodipine. The mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruits. Data have been conflicting and the clinical significance is unknown. Monitoring for calcium channel blocker adverse effects (e.g., headache, hypotension, syncope, tachycardia, edema) is recommended.

References

  1. Bailey DG, Arnold JMO, Spence JD "Grapefruit juice and drugs - how significant is the interaction." Clin Pharmacokinet 26 (1994): 91-8
  2. Josefsson M, Zackrisson AL, Ahlner J "Effect of grapefruit juice on the pharmacokinetics of amlodipine in healthy volunteers." Eur J Clin Pharmacol 51 (1996): 189-93
  3. Bailey DG, Malcolm J, Arnold O, Spence JD "Grapefruit juice-drug interactions." Br J Clin Pharmacol 46 (1998): 101-10
  4. Vincent J, Harris SI, Foulds G, Dogolo LC, Willavize S, Friedman HL "Lack of effect of grapefruit juice on the pharmacokinetics and pharmacodynamics of amlodipine." Br J Clin Pharmacol 50 (2000): 455-63
  5. Josefsson M, Ahlner J "Amlodipine and grapefruit juice." Br J Clin Pharmacol 53 (2002): 405; discussion 406
  6. Kane GC, Lipsky JJ "Drug-grapefruit juice interactions." Mayo Clin Proc 75 (2000): 933-42
View all 6 references

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Therapeutic duplication warnings

Therapeutic duplication is the use of more than one medicine from the same drug category or therapeutic class to treat the same condition. This can be intentional in cases where drugs with similar actions are used together for demonstrated therapeutic benefit. It can also be unintentional in cases where a patient has been treated by more than one doctor, or had prescriptions filled at more than one pharmacy, and can have potentially adverse consequences.

Duplication

Calcium channel blockers

Therapeutic duplication

The recommended maximum number of medicines in the 'calcium channel blockers' category to be taken concurrently is usually one. Your list includes two medicines belonging to the 'calcium channel blockers' category:

  • amlodipine
  • diltiazem

Note: In certain circumstances, the benefits of taking this combination of drugs may outweigh any risks. Always consult your healthcare provider before making changes to your medications or dosage.

See also

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Drug Interaction Classification

These classifications are only a guideline. The relevance of a particular drug interaction to a specific individual is difficult to determine. Always consult your healthcare provider before starting or stopping any medication.
Major Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit.
Moderate Moderately clinically significant. Usually avoid combinations; use it only under special circumstances.
Minor Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan.
Unknown No interaction information available.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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