Drug Interaction Report
10 potential interactions and/or warnings found for the following 2 drugs:
- emtricitabine / lopinavir / ritonavir / tenofovir disoproxil
- betamethasone / iodixanol / lidocaine
Interactions between your drugs
iodixanol tenofovir
Applies to: betamethasone / iodixanol / lidocaine, emtricitabine / lopinavir / ritonavir / tenofovir disoproxil
GENERALLY AVOID: Concomitant use of intravascular radiocontrast media with other nephrotoxic agents may potentiate the risk of contrast-induced nephropathy and renal impairment. Contrast-induced nephropathy is most commonly defined as an increase in serum creatinine >=0.5 mg/dL or 25% from baseline within 24 to 72 hours of intravascular contrast administration in the absence of alternative etiologies, although nephropathy may occur up to a week after contrast exposure. Pathogenesis has not been fully elucidated, but may involve renal hypoperfusion and ischemia, direct cytotoxicity on tubular epithelial cells, and generation of reactive oxygen species. While the condition is usually transient and asymptomatic, it can be associated with increased risk of renal failure, dialysis, prolonged hospitalization, significant long-term morbidity, and mortality. Patients at increased risk of developing contrast-induced nephropathy include those with diabetes (especially diabetic nephropathy), preexisting renal insufficiency (serum creatinine >1.5 mg/dL or GFR <60 mL/min/1.73 m2), volume depletion (e.g., diuretic use), advanced age (>70 years), congestive heart failure, multiple myeloma, hypoalbuminemia, and concomitant use of nephrotoxic agents (e.g., aminoglycosides; polypeptide, glycopeptide, and polymyxin antibiotics; amphotericin B; aminosalicylates; antiviral/antiretroviral agents such as acyclovir, adefovir, cidofovir, foscarnet, and tenofovir; antineoplastics such as aldesleukin, cisplatin, clofarabine, ifosfamide, streptozocin, and high intravenous dosages of methotrexate; chelating agents such as deferasirox, deferoxamine, edetate disodium, and edetate calcium disodium; immunosuppressants such as cyclosporine, everolimus, sirolimus, and tacrolimus; intravenous bisphosphonates; intravenous pentamidine; high dosages and/or chronic use of nonsteroidal anti-inflammatory agents; gallium nitrate; lithium; penicillamine). The incidence has been reported to be approximately 10% to 30% in patients with risk factors, and as high as 90% in diabetics with chronic kidney disease. Intraarterial administration of contrast media is also associated with increased risk of nephropathy relative to intravenous administration.
MANAGEMENT: Alternative imaging techniques that do not require contrast should be considered in patients who are at increased risk for contrast-induced nephropathy. Otherwise, experts recommend discontinuing other nephrotoxic drugs 1 to 2 days before administration of contrast media, depending on the clinical feasibility of doing so. The smallest effective dose (100 mL or less) of a nonionic, low-osmolar (e.g., iohexol, iomeprol, iopamidol, iopental, iopromide, ioversol) or iso-osmolar (e.g., iodixanol, iotrolan) contrast medium should be used whenever possible, since the risk of nephrotoxicity may be increased with increasing contrast dose, osmolarity, and ionicity. Some studies suggest a lower risk for iso-osmolar contrasts compared to low-osmolar contrasts, although data are limited. Serum creatinine levels should be measured before contrast administration (if procedure is not urgent) and continued for 24 to 48 hours after. In addition, patients should be adequately hydrated with either intravenous normal saline or sodium bicarbonate starting 3 (outpatient) to 6 (inpatient) hours before and continued for 6 to 24 hours after procedure. Oral fluids are also beneficial, but not as effective as intravenous hydration. N-acetylcysteine the day before and day of contrast administration, or theophylline up to 30 minutes before contrast administration, have also been used in high-risk or critically ill patients. Preferably, a nephrologist should be consulted to optimize prophylactic measures for preventing contrast-induced nephropathy in high-risk patients and to guide treatment if the condition occurs. Any repeat procedures with contrast media, if necessary, should not occur until at least 48 to 72 hours after the previous contrast exposure and renal function has fully recovered.
References (7)
- Bennett WM, Porter GA (1990) "Nephrotoxicity of common drugs used by urologists." Urol Clin North Am, 17, p. 145-56
- Bentley ML, Corwin HL, Dasta J (2010) "Drug-induced acute kidney injury in the critically ill adult: recognition and prevention strategies." Crit Care Med, 38(6 Suppl), S169-74
- Marcos LA, Camins BC, Ritchie DJ, Casabar E, Warren DK (2012) "Acute renal insufficiency during telavancin therapy in clinical practice." J Antimicrob Chemother, 67, p. 723-6
- Dubrovskaya Y, Prasad N, Lee Y, Esaian D, Figueroa DA, Tam VH (2015) "Risk factors for nephrotoxicity onset associated with polymyxin B therapy." J Antimicrob Chemother, 70, p. 1903-7
- Bansal R, Aflieco F, Kaplan AA (2016) Contrast-Induced Nephropathy. http://emedicine.medscape.com/article/246751-overview
- van den Berk G, Tonino S, de Fijter C, Smit W, Schultz MJ (2005) "Bench-to-bedside review: Preventative measures for contrast-induced nephropathy in critically ill patients." Crit Care, 9, p. 361-70
- Kellum JA, Leblanc M, Venkataraman R (2008) "Acute renal failure." BMJ Clin Evid, 9, p. 2001
lidocaine ritonavir
Applies to: betamethasone / iodixanol / lidocaine, emtricitabine / lopinavir / ritonavir / tenofovir disoproxil
MONITOR: Coadministration with moderate and potent inhibitors of CYP450 3A4 may increase the plasma concentrations of lidocaine, which is primarily metabolized by CYP450 3A4 and 1A2 isoenzymes to active metabolites (monoethylglycinexylidide (MEGX) and glycinexylidide). In addition, antiarrhythmic calcium channel blockers that also inhibit CYP450 3A4 (e.g., diltiazem, verapamil) may have additive negative inotropic effects on the heart when coadministered with lidocaine. A pharmacokinetic study of 9 healthy volunteers showed that the administration of lidocaine oral (1 mg/kg single dose) with itraconazole (200 mg daily), a combined potent CYP450 3A4 and P-gp inhibitor, increased lidocaine systemic exposure (AUC) and peak plasma concentration (Cmax) by 75% and 55%, respectively. However, no changes were observed in the pharmacokinetics of the active metabolite MEGX. In the same study, when the moderate CYP450 3A4 inhibitor erythromycin (500 mg three times a day) was administered, lidocaine AUC and Cmax increased by 60% and 40%, respectively. By contrast, when intravenous lidocaine (1.5 mg/kg infusion over 60 minutes) was administered on the fourth day of treatment with itraconazole (200 mg once a day) no changes in lidocaine AUC or Cmax were observed. However, when lidocaine (1.5 mg/kg infusion over 60 minutes) was coadministered with erythromycin (500 mg three times a day) in the same study, the AUC and Cmax of the active metabolite MEGX significantly increased by 45-60% and 40%, respectively. The observed differences between oral and intravenous lidocaine when coadministered with CYP450 3A4 inhibitors may be attributed to inhibition of CYP450 3A4 in both the gastrointestinal tract and liver affecting oral lidocaine to a greater extent than intravenous lidocaine. While the clinical significance of this interaction is unknown, increased exposure to lidocaine may lead to serious and/or life-threatening reactions including respiratory depression, convulsions, bradycardia, hypotension, arrhythmias and cardiovascular collapse.
MANAGEMENT: Caution and clinical monitoring are advised if lidocaine must be used concomitantly with moderate and potent CYP450 3A4 inhibitors. Monitoring of pharmacologic response and plasma lidocaine levels may be advised whenever a potent CYP450 3A4 inhibitor is added to or withdrawn from therapy, and the lidocaine dosage adjusted as necessary.
References (6)
- (2024) "Product Information. Lidocaine Hydrochloride (lidocaine)." Hospira Inc.
- (2015) "Product Information. Lidocaine Hydrochloride (lidocaine)." Hospira Healthcare Corporation
- (2022) "Product Information. Lidocaine Hydrochloride (lidocaine)." Hameln Pharma Ltd
- (2022) "Product Information. Xylocaine HCl (lidocaine)." Aspen Pharmacare Australia Pty Ltd
- Isohanni MH, Neuvonen PJ, Olkkola KT (2024) Effect of erythromycin and itraconazole on the pharmacokinetics of oral lignocaine https://pubmed.ncbi.nlm.nih.gov/10193676/
- Isohanni MH, Neuvonen PJ, Olkkola KT (2024) Effect of erythromycin and itraconazole on the pharmacokinetics of intravenous lignocaine https://pubmed.ncbi.nlm.nih.gov/9832299/
betamethasone ritonavir
Applies to: betamethasone / iodixanol / lidocaine, emtricitabine / lopinavir / ritonavir / tenofovir disoproxil
MONITOR: Coadministration with inhibitors of CYP450 3A4 may increase the plasma concentrations and pharmacologic effects of corticosteroids, which are primarily metabolized by the isoenzyme. The interaction has been reported with potent inhibitors such as clarithromycin, erythromycin, itraconazole, nefazodone, cobicistat, and ritonavir during concomitant use of various corticosteroids, including inhaled, nasal, and ophthalmic formulations. Systemic corticosteroid adverse effects may occur following intensive or long-term continuous ophthalmic corticosteroid therapy. Cushing's syndrome and adrenal insufficiency have been attributed to the interaction.
MANAGEMENT: The possibility of increased corticosteroid effects should be considered during coadministration with potent and moderate CYP450 3A4 inhibitors. Some authorities advise against concomitant use unless the potential benefit outweighs the risk. If the combination is considered necessary, a lower dosage of the corticosteroid may be required. When indicated for intranasal or inhalational use, alternative corticosteroids such as beclomethasone, which is less dependent on CYP450 3A4 metabolism, should be considered, particularly if long term treatment is required. Patients should be monitored for signs and symptoms of hypercorticism such as acne, striae, thinning of the skin, easy bruising, moon facies, dorsocervical "buffalo" hump, truncal obesity, increased appetite, acute weight gain, edema, hypertension, hirsutism, hyperhidrosis, proximal muscle wasting and weakness, glucose intolerance, exacerbation of preexisting diabetes, depression, and menstrual disorders. Other systemic glucocorticoid effects may include adrenal suppression, immunosuppression, posterior subcapsular cataracts, glaucoma, bone loss, and growth retardation in children and adolescents. Following extensive use with a potent CYP450 3A4 inhibitor, a progressive dosage reduction may be required over a longer period if the corticosteroid is to be withdrawn from therapy, as there may be a significant risk of adrenal suppression. Signs and symptoms of adrenal insufficiency include anorexia, hypoglycemia, nausea, vomiting, weight loss, muscle wasting, fatigue, weakness, dizziness, postural hypotension, depression, and adrenal crisis manifested as inability to respond to stress (e.g., illness, infection, surgery, trauma).
References (29)
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- Ulrich B, Frey FJ, Speck RF, Frey BM (1992) "Pharmacokinetics/pharmacodynamics of ketoconazole-prednisolone interaction." J Pharmacol Exp Ther, 260, p. 487-90
- Kandrotas RJ, Slaughter RL, Brass C, Jusko WJ (1987) "Ketoconazole effects on methylprednisolone disposition and their joint suppression of endogenous cortisol." Clin Pharmacol Ther, 42, p. 465-70
- Glynn AM, Slaughter RL, Brass C, et al. (1986) "Effects of ketoconazole on methylprednisolone pharmacokinetics and cortisol secretion." Clin Pharmacol Ther, 39, p. 654-9
- Itkin IH, Menzel ML (1970) "The use of macrolide antibiotic substances in the treatment of asthma." J Allergy Clin Immunol, 45, p. 146-62
- LaForce CF, Szefler SJ, Miller MF, Ebling W, Brenner M (1983) "Inhibition of methylprednisolone elimination in the presence of erythromycin therapy." J Allergy Clin Immunol, 72, p. 34-9
- Finkenbine RD, Frye MD (1998) "Case of psychosis due to prednisone-clarithromycin interaction." Gen Hosp Psychiat, 20, p. 325-6
- Varis T, Kaukonen KM, Kivisto KT, Neuvonen PJ (1998) "Plasma concentrations and effects of oral methylprednisolone are considerably increased by itraconazole." Clin Pharmacol Ther, 64, p. 363-8
- Hillebrand-Haverkort ME, Prummel MF, ten Veen JH (1999) "Ritonavir-induced Cushing's syndrome in a patient treated with nasal fluticasone." AIDS, 13, p. 1803
- Varis T, Kivisto KT, Neuvonen PJ (2000) "The effect of itraconazole on the pharmacokinetics and pharmacodynamics of oral prednisolone." Eur J Clin Pharmacol, 56, p. 57-60
- Varis T, Backman JT, Kivisto KT, Neuvonen PJ (2000) "Diltiazem and mibefradil increase the plasma concentrations and greatly enhance the adrenal-suppressant effect of oral methylprednisolone." Clin Pharmacol Ther, 67, p. 215-21
- Garey KW, Rubinstein I, Gotfried MH, Khan IJ, Varma S, Danziger LH (2000) "Long-term clarithromycin decreases prednisone requirements in elderly patients with prednisone-dependent asthma." Chest, 118, p. 1826-7
- Lebrun-Vignes B, Archer VC, Diquest B, et al. (2001) "Effect of itraconazole on the pharmacokinetics of prednisolone and methylprednisolone and cortisol secretion in healthy subjects." Br J Clin Pharmacol, 51, p. 443-50
- Couturier J, Steele M, Hussey L, Pawliuk G (2001) "Steroid-induced mania in an adolescent: risk factors and management." Can J Clin Pharmacol, 8, p. 109-12
- Gupta SK, Dube MP (2002) "Exogenous Cushing syndrome mimicking human immunodeficiency virus lipodystrophy." Clin Infect Dis, 35, E69-71
- Raaska K, Niemi M, Neuvonen M, Neuvonen PJ, Kivisto KT (2002) "Plasma concentrations of inhaled budesonide and its effects on plasma cortisol are increased by the cytochrome P4503A4 inhibitor itraconazole." Clin Pharmacol Ther, 72, p. 362-369
- Main KM, Skov M, Sillesen IB, et al. (2002) "Cushing's syndrome due to pharmacological interaction in a cystic fibrosis patient." Acta Paediatr, 91, p. 1008-11
- Skov M, Main KM, Sillesen IB, Muller J, Koch C, Lanng S (2002) "Iatrogenic adrenal insufficiency as a side-effect of combined treatment of itraconazole and budesonide." Eur Respir J, 20, p. 127-33
- Kotlyar M, Brewer ER, Golding M, Carson SW (2003) "Nefazodone inhibits methylprednisolone disposition and enhances its adrenal-suppressant effect." J Clin Psychopharmacol, 23, p. 652-6
- Bolland MJ, Bagg W, Thomas MG, Lucas JA, Ticehurst R, Black PN (2004) "Cushing's syndrome due to interaction between inhaled corticosteroids and itraconazole." Ann Pharmacother, 38, p. 46-9
- Edsbacker S, Andersson T (2004) "Pharmacokinetics of budesonide (Entocort EC) capsules for Crohn's disease." Clin Pharmacokinet, 43, p. 803-21
- Samaras K, Pett S, Gowers A, McMurchie M, Cooper DA (2005) "Iatrogenic Cushing's syndrome with osteoporosis and secondary adrenal failure in HIV-infected patients receiving inhaled corticosteroids and ritonavir-boosted protease inhibitors: six cases." J Clin Endocrinol Metab, 90, p. 4394-8
- Soldatos G, Sztal-Mazer S, Woolley I, Stockigt J (2005) "Exogenous glucocorticoid excess as a result of ritonavir-fluticasone interaction." Intern Med J, 35, p. 67-8
- Penzak SR, Formentini E, Alfaro RM, Long M, Natarajan V, Kovacs J (2005) "Prednisolone pharmacokinetics in the presence and absence of ritonavir after oral prednisone administration to healthy volunteers." J Acquir Immune Defic Syndr, 40, p. 573-80
- EMEA. European Medicines Agency (2007) EPARs. European Union Public Assessment Reports. http://www.ema.europa.eu/ema/index.jsp?curl=pages/includes/medicines/medicines_landingpage.jsp&mid
- Bhumbra NA, Sahloff EG, Oehrtman SJ, Horner JM (2007) "Exogenous Cushing syndrome with inhaled fluticasone in a child receiving lopinavir/ritonavir." Ann Pharmacother, 41, p. 1306-9
- Busse KH, Formentini E, Alfaro RM, Kovacs JA, Penzak SR (2008) "Influence of antiretroviral drugs on the pharmacokinetics of prednisolone in HIV-infected individuals." J Acquir Immune Defic Syndr, 48, p. 561-6
- Agencia Española de Medicamentos y Productos Sanitarios Healthcare (2008) Centro de información online de medicamentos de la AEMPS - CIMA. https://cima.aemps.es/cima/publico/home.html
ritonavir tenofovir
Applies to: emtricitabine / lopinavir / ritonavir / tenofovir disoproxil, emtricitabine / lopinavir / ritonavir / tenofovir disoproxil
MONITOR: Coadministration with ritonavir, with or without lopinavir, has been suggested in postmarketing reports to increase the proximal tubular intracellular concentrations of tenofovir and potentiate the risk of tenofovir-induced nephrotoxicity. The proposed mechanism is ritonavir inhibition of tenofovir renal tubular secretion into the urine via multidrug resistance protein MRP2. Analysis of data from a compassionate access study in which 271 patients with advanced HIV disease received the combination for a mean duration of 63 weeks revealed no clinically significant nephrotoxicity associated with coadministration. However, there have been case reports of renal failure associated with acute tubular necrosis, Fanconi's syndrome, and nephrogenic diabetes insipidus in patients treated with tenofovir disoproxil fumarate in combination with ritonavir. Some patients had incomplete recovery of renal function more than a year after cessation of tenofovir therapy. Ritonavir given in combination with lopinavir has also been reported to modestly increase the plasma concentrations of tenofovir. In contrast, both slight decreases and no change in lopinavir and ritonavir concentrations have been reported.
MANAGEMENT: Caution is advised if tenofovir disoproxil fumarate is prescribed with ritonavir. Renal function should be monitored regularly, including surveillance for signs of tubulopathy such as glycosuria, acidosis, increases in serum creatinine level, electrolyte disturbances (e.g., hypokalemia, hypophosphatemia), and proteinuria. The same precaution may be applicable during therapy with other protease inhibitors based on their similar pharmacokinetic profile, although clinical data are lacking. Nelfinavir reportedly does not alter the pharmacokinetics of tenofovir, or vice versa. Tenofovir administration should be discontinued promptly if nephropathy develops.
References (8)
- (2001) "Product Information. Viread (tenofovir)." Gilead Sciences
- Verhelst D, Monge M, Meynard JL, et al. (2002) "Fanconi syndrome and renal failure induced by tenofovir: A first case report." Am J Kidney Dis, 40, p. 1331-3
- Creput C, Gonzalez-Canali G, Hill G, Piketty C, Kazatchkine M, Nochy D (2003) "Renal lesions in HIV-1-positive patient treated with tenofovir." AIDS, 17, p. 935-7
- Karras A, Lafaurie M, Furco A, et al. (2003) "Tenofovir-related nephrotoxicity in human immunodeficiency virus-infected patients: three cases of renal failure, fanconi syndrome, and nephrogenic diabetes insipidus." Clin Infect Dis, 36, p. 1070-3
- Kearney BP, Mittan A, Sayre J, et al. (2003) Pharmacokinetic drug interaction and long term safety profile of tenofovir DF and lopinavir/ritonavir. http://www.icaac.org/ICAAC.asp
- Rollot F, Nazal EM, Chauvelot-Moachon L, et al. (2003) "Tenofovir-related fanconi syndrome with nephrogenic diabetes insipidus in a patient with acquired immunodeficiency syndrome: the role of lopinavir-ritonavir-Didanosine." Clin Infect Dis, 37, E174-6
- Zimmermann AE, Pizzoferrato T, Bedford J, Morris A, Hoffman R, Braden G (2006) "Tenofovir-associated acute and chronic kidney disease: a case of multiple drug interactions." Clin Infect Dis, 42, p. 283-90
- Kapadia J, Shah S, Desai C, et al. (2013) "Tenofovir induced Fanconi syndrome: a possible pharmacokinetic interaction." Indian J Pharmacol, 45, p. 191-2
lopinavir tenofovir
Applies to: emtricitabine / lopinavir / ritonavir / tenofovir disoproxil, emtricitabine / lopinavir / ritonavir / tenofovir disoproxil
MONITOR: Coadministration with ritonavir, with or without lopinavir, has been suggested in postmarketing reports to increase the proximal tubular intracellular concentrations of tenofovir and potentiate the risk of tenofovir-induced nephrotoxicity. The proposed mechanism is ritonavir inhibition of tenofovir renal tubular secretion into the urine via multidrug resistance protein MRP2. Analysis of data from a compassionate access study in which 271 patients with advanced HIV disease received the combination for a mean duration of 63 weeks revealed no clinically significant nephrotoxicity associated with coadministration. However, there have been case reports of renal failure associated with acute tubular necrosis, Fanconi's syndrome, and nephrogenic diabetes insipidus in patients treated with tenofovir disoproxil fumarate in combination with ritonavir. Some patients had incomplete recovery of renal function more than a year after cessation of tenofovir therapy. Ritonavir given in combination with lopinavir has also been reported to modestly increase the plasma concentrations of tenofovir. In contrast, both slight decreases and no change in lopinavir and ritonavir concentrations have been reported.
MANAGEMENT: Caution is advised if tenofovir disoproxil fumarate is prescribed with ritonavir. Renal function should be monitored regularly, including surveillance for signs of tubulopathy such as glycosuria, acidosis, increases in serum creatinine level, electrolyte disturbances (e.g., hypokalemia, hypophosphatemia), and proteinuria. The same precaution may be applicable during therapy with other protease inhibitors based on their similar pharmacokinetic profile, although clinical data are lacking. Nelfinavir reportedly does not alter the pharmacokinetics of tenofovir, or vice versa. Tenofovir administration should be discontinued promptly if nephropathy develops.
References (8)
- (2001) "Product Information. Viread (tenofovir)." Gilead Sciences
- Verhelst D, Monge M, Meynard JL, et al. (2002) "Fanconi syndrome and renal failure induced by tenofovir: A first case report." Am J Kidney Dis, 40, p. 1331-3
- Creput C, Gonzalez-Canali G, Hill G, Piketty C, Kazatchkine M, Nochy D (2003) "Renal lesions in HIV-1-positive patient treated with tenofovir." AIDS, 17, p. 935-7
- Karras A, Lafaurie M, Furco A, et al. (2003) "Tenofovir-related nephrotoxicity in human immunodeficiency virus-infected patients: three cases of renal failure, fanconi syndrome, and nephrogenic diabetes insipidus." Clin Infect Dis, 36, p. 1070-3
- Kearney BP, Mittan A, Sayre J, et al. (2003) Pharmacokinetic drug interaction and long term safety profile of tenofovir DF and lopinavir/ritonavir. http://www.icaac.org/ICAAC.asp
- Rollot F, Nazal EM, Chauvelot-Moachon L, et al. (2003) "Tenofovir-related fanconi syndrome with nephrogenic diabetes insipidus in a patient with acquired immunodeficiency syndrome: the role of lopinavir-ritonavir-Didanosine." Clin Infect Dis, 37, E174-6
- Zimmermann AE, Pizzoferrato T, Bedford J, Morris A, Hoffman R, Braden G (2006) "Tenofovir-associated acute and chronic kidney disease: a case of multiple drug interactions." Clin Infect Dis, 42, p. 283-90
- Kapadia J, Shah S, Desai C, et al. (2013) "Tenofovir induced Fanconi syndrome: a possible pharmacokinetic interaction." Indian J Pharmacol, 45, p. 191-2
Drug and food interactions
lidocaine food
Applies to: betamethasone / iodixanol / lidocaine
MONITOR: Grapefruit and grapefruit juice may increase the plasma concentrations of lidocaine, which is primarily metabolized by the CYP450 3A4 and 1A2 isoenzymes to active metabolites (monoethylglycinexylidide (MEGX) and glycinexylidide). The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruit. Inhibition of hepatic CYP450 3A4 may also contribute. The interaction has not been studied with grapefruit juice but has been reported with oral and/or intravenous lidocaine and potent CYP450 3A4 inhibitor, itraconazole, as well as moderate CYP450 3A4 inhibitor, erythromycin. A pharmacokinetic study of 9 healthy volunteers showed that the administration of lidocaine oral (1 mg/kg single dose) with itraconazole (200 mg daily) increased lidocaine systemic exposure (AUC) and peak plasma concentration (Cmax) by 75% and 55%, respectively. However, no changes were observed in the pharmacokinetics of the active metabolite MEGX. In the same study, when the moderate CYP450 3A4 inhibitor erythromycin (500 mg three times a day) was administered, lidocaine AUC and Cmax increased by 60% and 40%, respectively. By contrast, when intravenous lidocaine (1.5 mg/kg infusion over 60 minutes) was administered on the fourth day of treatment with itraconazole (200 mg once a day) no changes in lidocaine AUC or Cmax were observed. However, when lidocaine (1.5 mg/kg infusion over 60 minutes) was coadministered with erythromycin (500 mg three times a day) in the same study, the AUC and Cmax of the active metabolite MEGX significantly increased by 45-60% and 40%, respectively. The observed differences between oral and intravenous lidocaine when coadministered with CYP450 3A4 inhibitors may be attributed to inhibition of CYP450 3A4 in both the gastrointestinal tract and liver affecting oral lidocaine to a greater extent than intravenous lidocaine. In general, the effects of grapefruit products are concentration-, dose- and preparation-dependent, and can vary widely among brands. Certain preparations of grapefruit (e.g., high dose, double strength) have sometimes demonstrated potent inhibition of CYP450 3A4, while other preparations (e.g., low dose, single strength) have typically demonstrated moderate inhibition. While the clinical significance of this interaction is unknown, increased exposure to lidocaine may lead to serious and/or life-threatening reactions including respiratory depression, convulsions, bradycardia, hypotension, arrhythmias, and cardiovascular collapse.
MONITOR: Certain foods and behaviors that induce CYP450 1A2 may reduce the plasma concentrations of lidocaine. The proposed mechanism is induction of hepatic CYP450 1A2, one of the isoenzymes responsible for the metabolic clearance of lidocaine. Cigarette smoking is known to be a CYP450 1A2 inducer. In one pharmacokinetic study of 4 smokers and 5 non-smokers who received 2 doses of lidocaine (100 mg IV followed by 100 mg orally after a 2-day washout period), the smokers' systemic exposure (AUC) of oral lidocaine was 68% lower than non-smokers. The AUC of IV lidocaine was only 9% lower in smokers compared with non-smokers. Other CYP450 1A2 inducers include cruciferous vegetables (e.g., broccoli, brussels sprouts) and char-grilled meat. Therefore, eating large or variable amounts of these foods could also reduce lidocaine exposure. The clinical impact of smoking and/or the ingestion of foods that induce CYP450 1A2 on lidocaine have not been studied, however, a loss of efficacy may occur.
MANAGEMENT: Caution is recommended if lidocaine is to be used in combination with grapefruit and grapefruit juice. Monitoring for lidocaine toxicity and plasma lidocaine levels may also be advised, and the lidocaine dosage adjusted as necessary. Patients who smoke and/or consume cruciferous vegetables may be monitored for reduced lidocaine efficacy.
References (7)
- Huet PM, LeLorier J (1980) "Effects of smoking and chronic hepatitis B on lidocaine and indocyanine green kinetics" Clin Pharmacol Ther, 28, p. 208-15
- (2024) "Product Information. Lidocaine Hydrochloride (lidocaine)." Hospira Inc.
- (2015) "Product Information. Lidocaine Hydrochloride (lidocaine)." Hospira Healthcare Corporation
- (2022) "Product Information. Lidocaine Hydrochloride (lidocaine)." Hameln Pharma Ltd
- (2022) "Product Information. Xylocaine HCl (lidocaine)." Aspen Pharmacare Australia Pty Ltd
- Isohanni MH, Neuvonen PJ, Olkkola KT (2024) Effect of erythromycin and itraconazole on the pharmacokinetics of oral lignocaine https://pubmed.ncbi.nlm.nih.gov/10193676/
- Isohanni MH, Neuvonen PJ, Olkkola KT (2024) Effect of erythromycin and itraconazole on the pharmacokinetics of intravenous lignocaine https://pubmed.ncbi.nlm.nih.gov/9832299/
ritonavir food
Applies to: emtricitabine / lopinavir / ritonavir / tenofovir disoproxil
ADJUST DOSING INTERVAL: Administration with food may modestly affect the bioavailability of ritonavir from the various available formulations. When the oral solution was given under nonfasting conditions, peak ritonavir concentrations decreased 23% and the extent of absorption decreased 7% relative to fasting conditions. Dilution of the oral solution (within one hour of dosing) with 240 mL of chocolate milk or a nutritional supplement (Advera or Ensure) did not significantly affect the extent and rate of ritonavir absorption. When a single 100 mg dose of the tablet was administered with a high-fat meal (907 kcal; 52% fat, 15% protein, 33% carbohydrates), approximately 20% decreases in mean peak concentration (Cmax) and systemic exposure (AUC) were observed relative to administration after fasting. Similar decreases in Cmax and AUC were reported when the tablet was administered with a moderate-fat meal. In contrast, the extent of absorption of ritonavir from the soft gelatin capsule formulation was 13% higher when administered with a meal (615 KCal; 14.5% fat, 9% protein, and 76% carbohydrate) relative to fasting.
MANAGEMENT: Ritonavir should be taken with meals to enhance gastrointestinal tolerability.
References (1)
- (2001) "Product Information. Norvir (ritonavir)." Abbott Pharmaceutical
lopinavir food
Applies to: emtricitabine / lopinavir / ritonavir / tenofovir disoproxil
ADJUST DOSING INTERVAL: Food significantly increases the bioavailability of lopinavir from the oral solution formulation of lopinavir-ritonavir. Relative to fasting, administration of lopinavir-ritonavir oral solution with a moderate-fat meal (500 to 682 Kcal; 23% to 25% calories from fat) increased lopinavir peak plasma concentration (Cmax) and systemic exposure (AUC) by 54% and 80%, respectively, whereas administration with a high-fat meal (872 Kcal; 56% from fat) increased lopinavir Cmax and AUC by 56% and 130%, respectively. No clinically significant changes in Cmax and AUC were observed following administration of lopinavir-ritonavir tablets under fed conditions versus fasted conditions. Relative to fasting, administration of a single 400 mg-100 mg dose (two 200 mg-50 mg tablets) with a moderate-fat meal (558 Kcal; 24.1% calories from fat) increased lopinavir Cmax and AUC by 17.6% and 26.9%, respectively, while administration with a high-fat meal (998 Kcal; 51.3% from fat) increased lopinavir AUC by 18.9% but not Cmax. Relative to fasting, ritonavir Cmax and AUC also increased by 4.9% and 14.9%, respectively, with the moderate-fat meal and 10.3% and 23.9%, respectively, with the high-fat meal.
MANAGEMENT: Lopinavir-ritonavir oral solution should be taken with meals to enhance bioavailability and minimize pharmacokinetic variability. Lopinavir-ritonavir tablets may be taken without regard to meals.
References (1)
- (2001) "Product Information. Kaletra (lopinavir-ritonavir)." Abbott Pharmaceutical
lidocaine food
Applies to: betamethasone / iodixanol / lidocaine
MONITOR: Smoking cessation may lead to elevated plasma concentrations and enhanced pharmacologic effects of drugs that are substrates of CYP450 1A2 (and possibly CYP450 1A1) and/or certain drugs with a narrow therapeutic index (e.g., flecainide, pentazocine). One proposed mechanism is related to the loss of CYP450 1A2 and 1A1 induction by polycyclic aromatic hydrocarbons in tobacco smoke; when smoking cessation agents are initiated and smoking stops, the metabolism of certain drugs may decrease leading to increased plasma concentrations. The mechanism by which smoking cessation affects narrow therapeutic index drugs that are not known substrates of CYP450 1A2 or 1A1 is unknown. The clinical significance of this interaction is unknown as clinical data are lacking.
MANAGEMENT: Until more information is available, caution is advisable if smoking cessation agents are used concomitantly with drugs that are substrates of CYP450 1A2 or 1A1 and/or those with a narrow therapeutic range. Patients receiving smoking cessation agents may require periodic dose adjustments and closer clinical and laboratory monitoring of medications that are substrates of CYP450 1A2 or 1A1.
References (4)
- (2024) "Product Information. Cytisine (cytisinicline)." Consilient Health Ltd
- jeong sh, Newcombe D, sheridan j, Tingle M (2015) "Pharmacokinetics of cytisine, an a4 b2 nicotinic receptor partial agonist, in healthy smokers following a single dose." Drug Test Anal, 7, p. 475-82
- Vaughan DP, Beckett AH, Robbie DS (1976) "The influence of smoking on the intersubject variation in pentazocine elimination." Br J Clin Pharmacol, 3, p. 279-83
- Zevin S, Benowitz NL (1999) "Drug interactions with tobacco smoking: an update" Clin Pharmacokinet, 36, p. 425-38
tenofovir food
Applies to: emtricitabine / lopinavir / ritonavir / tenofovir disoproxil
Food enhances the oral absorption and bioavailability of tenofovir, the active entity of tenofovir disoproxil fumarate. According to the product labeling, administration of the drug following a high-fat meal increased the mean peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) of tenofovir by approximately 14% and 40%, respectively, compared to administration in the fasting state. However, administration with a light meal did not significantly affect the pharmacokinetics of tenofovir compared to administration in the fasting state. Food delays the time to reach tenofovir Cmax by approximately 1 hour. Tenofovir disoproxil fumarate may be administered without regard to meals.
References (1)
- (2001) "Product Information. Viread (tenofovir)." Gilead Sciences
Therapeutic duplication warnings
No duplication warnings were found for your selected drugs.
Therapeutic duplication warnings are only returned when drugs within the same group exceed the recommended therapeutic duplication maximum.
Drug Interaction Classification
| Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit. | |
| Moderately clinically significant. Usually avoid combinations; use it only under special circumstances. | |
| 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. | |
| No interaction information available. |
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