Drug Interactions between levodopa and Respa C&C
This report displays the potential drug interactions for the following 2 drugs:
- levodopa
- Respa C&C (acetaminophen/dextromethorphan/diphenhydramine/phenylephrine)
Interactions between your drugs
dextromethorphan diphenhydrAMINE
Applies to: Respa C&C (acetaminophen / dextromethorphan / diphenhydramine / phenylephrine) and Respa C&C (acetaminophen / dextromethorphan / diphenhydramine / phenylephrine)
MONITOR: Central nervous system- and/or respiratory-depressant effects may be additively or synergistically increased in patients taking multiple drugs that cause these effects, especially in elderly or debilitated patients. Sedation and impairment of attention, judgment, thinking, and psychomotor skills may increase.
MANAGEMENT: During concomitant use of these drugs, patients should be monitored for potentially excessive or prolonged CNS and respiratory depression. Cautious dosage titration may be required, particularly at treatment initiation. Ambulatory patients should be counseled to avoid hazardous activities requiring mental alertness and motor coordination until they know how these agents affect them, and to notify their physician if they experience excessive or prolonged CNS effects that interfere with their normal activities.
References
- Hamilton MJ, Bush M, Smith P, Peck AW (1982) "The effects of bupropion, a new antidepressant drug, and diazepam, and their interaction in man." Br J Clin Pharmacol, 14, p. 791-7
- Stambaugh JE, Lane C (1983) "Analgesic efficacy and pharmacokinetic evaluation of meperidine and hydroxyzine, alone and in combination." Cancer Invest, 1, p. 111-7
- Sotaniemi EA, Anttila M, Rautio A, et al. (1981) "Propranolol and sotalol metabolism after a drinking party." Clin Pharmacol Ther, 29, p. 705-10
- Grabowski BS, Cady WJ, Young WW, Emery JF (1980) "Effects of acute alcohol administration on propranolol absorption." Int J Clin Pharmacol Ther Toxicol, 18, p. 317-9
- Lemberger L, Rowe H, Bosomworth JC, Tenbarge JB, Bergstrom RF (1988) "The effect of fluoxetine on the pharmacokinetics and psychomotor responses of diazepam." Clin Pharmacol Ther, 43, p. 412-9
- MacLeod SM, Giles HG, Patzalek G, Thiessen JJ, Sellers EM (1977) "Diazepam actions and plasma concentrations following ethanol ingestion." Eur J Clin Pharmacol, 11, p. 345-9
- Divoll M, Greenblatt DJ, Lacasse Y, Shader RI (1981) "Benzodiazepine overdosage: plasma concentrations and clinical outcome." Psychopharmacology (Berl), 73, p. 381-3
- Naylor GJ, McHarg A (1977) "Profound hypothermia on combined lithium carbonate and diazepam treatment." Br Med J, 2, p. 22
- Stovner J, Endresen R (1965) "Intravenous anaesthesia with diazepam." Acta Anaesthesiol Scand, 24, p. 223-7
- Driessen JJ, Vree TB, Booij LH, van der Pol FM, Crul JF (1984) "Effect of some benzodiazepines on peripheral neuromuscular function in the rat in-vitro hemidiaphragm preparation." J Pharm Pharmacol, 36, p. 244-7
- Feldman SA, Crawley BE (1970) "Interaction of diazepam with the muscle-relaxant drugs." Br Med J, 1, p. 336-8
- Ochs HR, Greenblatt DJ, Verburg-Ochs B (1984) "Propranolol interactions with diazepam, lorazepam and alprazolam." Clin Pharmacol Ther, 36, p. 451-5
- Desager JP, Hulhoven R, Harvengt C, Hermann P, Guillet P, Thiercelin JF (1988) "Possible interactions between zolpidem, a new sleep inducer and chlorpromazine, a phenothiazine neuroleptic." Psychopharmacology (Berl), 96, p. 63-6
- Tverskoy M, Fleyshman G, Ezry J, Bradley EL, Jr Kissin I (1989) "Midazolam-morphine sedative interaction in patients." Anesth Analg, 68, p. 282-5
- "Product Information. Iopidine (apraclonidine ophthalmic)." Alcon Laboratories Inc
- Greiff JMC, Rowbotham D (1994) "Pharmacokinetic drug interactions with gastrointestinal motility modifying agents." Clin Pharmacokinet, 27, p. 447-61
- Greb WH, Buscher G, Dierdorf HD, Koster FE, Wolf D, Mellows G (1989) "The effect of liver enzyme inhibition by cimetidine and enzyme induction by phenobarbitone on the pharmacokinetics of paroxetine." Acta Psychiatr Scand, 80 Suppl, p. 95-8
- Markowitz JS, Wells BG, Carson WH (1995) "Interactions between antipsychotic and antihypertensive drugs." Ann Pharmacother, 29, p. 603-9
- (2001) "Product Information. Ultram (tramadol)." McNeil Pharmaceutical
- (2001) "Product Information. Artane (trihexyphenidyl)." Lederle Laboratories
- (2001) "Product Information. Ultiva (remifentanil)." Mylan Institutional (formally Bioniche Pharma USA Inc)
- (2001) "Product Information. Seroquel (quetiapine)." Astra-Zeneca Pharmaceuticals
- (2001) "Product Information. Meridia (sibutramine)." Knoll Pharmaceutical Company
- (2001) "Product Information. Tasmar (tolcapone)." Valeant Pharmaceuticals
- Miller LG (1998) "Herbal medicinals: selected clinical considerations focusing on known or potential drug-herb interactions." Arch Intern Med, 158, p. 2200-11
- (2001) "Product Information. Precedex (dexmedetomidine)." Abbott Pharmaceutical
- (2001) "Product Information. Trileptal (oxcarbazepine)." Novartis Pharmaceuticals
- Ferslew KE, Hagardorn AN, McCormick WF (1990) "A fatal interaction of methocarbamol and ethanol in an accidental poisoning." J Forensic Sci, 35, p. 477-82
- Plushner SL (2000) "Valerian: valeriana officinalis." Am J Health Syst Pharm, 57, p. 328-35
- (2002) "Product Information. Xatral (alfuzosin)." Sanofi-Synthelabo Canada Inc
- (2002) "Product Information. Lexapro (escitalopram)." Forest Pharmaceuticals
- Cerner Multum, Inc. "UK Summary of Product Characteristics."
- Cerner Multum, Inc. "Australian Product Information."
- (2012) "Product Information. Fycompa (perampanel)." Eisai Inc
- (2014) "Product Information. Belsomra (suvorexant)." Merck & Co., Inc
- (2015) "Product Information. Rexulti (brexpiprazole)." Otsuka American Pharmaceuticals Inc
dextromethorphan levodopa
Applies to: Respa C&C (acetaminophen / dextromethorphan / diphenhydramine / phenylephrine) and levodopa
MONITOR: Central nervous system- and/or respiratory-depressant effects may be additively or synergistically increased in patients taking multiple drugs that cause these effects, especially in elderly or debilitated patients. Sedation and impairment of attention, judgment, thinking, and psychomotor skills may increase.
MANAGEMENT: During concomitant use of these drugs, patients should be monitored for potentially excessive or prolonged CNS and respiratory depression. Cautious dosage titration may be required, particularly at treatment initiation. Ambulatory patients should be counseled to avoid hazardous activities requiring mental alertness and motor coordination until they know how these agents affect them, and to notify their physician if they experience excessive or prolonged CNS effects that interfere with their normal activities.
References
- Hamilton MJ, Bush M, Smith P, Peck AW (1982) "The effects of bupropion, a new antidepressant drug, and diazepam, and their interaction in man." Br J Clin Pharmacol, 14, p. 791-7
- Stambaugh JE, Lane C (1983) "Analgesic efficacy and pharmacokinetic evaluation of meperidine and hydroxyzine, alone and in combination." Cancer Invest, 1, p. 111-7
- Sotaniemi EA, Anttila M, Rautio A, et al. (1981) "Propranolol and sotalol metabolism after a drinking party." Clin Pharmacol Ther, 29, p. 705-10
- Grabowski BS, Cady WJ, Young WW, Emery JF (1980) "Effects of acute alcohol administration on propranolol absorption." Int J Clin Pharmacol Ther Toxicol, 18, p. 317-9
- Lemberger L, Rowe H, Bosomworth JC, Tenbarge JB, Bergstrom RF (1988) "The effect of fluoxetine on the pharmacokinetics and psychomotor responses of diazepam." Clin Pharmacol Ther, 43, p. 412-9
- MacLeod SM, Giles HG, Patzalek G, Thiessen JJ, Sellers EM (1977) "Diazepam actions and plasma concentrations following ethanol ingestion." Eur J Clin Pharmacol, 11, p. 345-9
- Divoll M, Greenblatt DJ, Lacasse Y, Shader RI (1981) "Benzodiazepine overdosage: plasma concentrations and clinical outcome." Psychopharmacology (Berl), 73, p. 381-3
- Naylor GJ, McHarg A (1977) "Profound hypothermia on combined lithium carbonate and diazepam treatment." Br Med J, 2, p. 22
- Stovner J, Endresen R (1965) "Intravenous anaesthesia with diazepam." Acta Anaesthesiol Scand, 24, p. 223-7
- Driessen JJ, Vree TB, Booij LH, van der Pol FM, Crul JF (1984) "Effect of some benzodiazepines on peripheral neuromuscular function in the rat in-vitro hemidiaphragm preparation." J Pharm Pharmacol, 36, p. 244-7
- Feldman SA, Crawley BE (1970) "Interaction of diazepam with the muscle-relaxant drugs." Br Med J, 1, p. 336-8
- Ochs HR, Greenblatt DJ, Verburg-Ochs B (1984) "Propranolol interactions with diazepam, lorazepam and alprazolam." Clin Pharmacol Ther, 36, p. 451-5
- Desager JP, Hulhoven R, Harvengt C, Hermann P, Guillet P, Thiercelin JF (1988) "Possible interactions between zolpidem, a new sleep inducer and chlorpromazine, a phenothiazine neuroleptic." Psychopharmacology (Berl), 96, p. 63-6
- Tverskoy M, Fleyshman G, Ezry J, Bradley EL, Jr Kissin I (1989) "Midazolam-morphine sedative interaction in patients." Anesth Analg, 68, p. 282-5
- "Product Information. Iopidine (apraclonidine ophthalmic)." Alcon Laboratories Inc
- Greiff JMC, Rowbotham D (1994) "Pharmacokinetic drug interactions with gastrointestinal motility modifying agents." Clin Pharmacokinet, 27, p. 447-61
- Greb WH, Buscher G, Dierdorf HD, Koster FE, Wolf D, Mellows G (1989) "The effect of liver enzyme inhibition by cimetidine and enzyme induction by phenobarbitone on the pharmacokinetics of paroxetine." Acta Psychiatr Scand, 80 Suppl, p. 95-8
- Markowitz JS, Wells BG, Carson WH (1995) "Interactions between antipsychotic and antihypertensive drugs." Ann Pharmacother, 29, p. 603-9
- (2001) "Product Information. Ultram (tramadol)." McNeil Pharmaceutical
- (2001) "Product Information. Artane (trihexyphenidyl)." Lederle Laboratories
- (2001) "Product Information. Ultiva (remifentanil)." Mylan Institutional (formally Bioniche Pharma USA Inc)
- (2001) "Product Information. Seroquel (quetiapine)." Astra-Zeneca Pharmaceuticals
- (2001) "Product Information. Meridia (sibutramine)." Knoll Pharmaceutical Company
- (2001) "Product Information. Tasmar (tolcapone)." Valeant Pharmaceuticals
- Miller LG (1998) "Herbal medicinals: selected clinical considerations focusing on known or potential drug-herb interactions." Arch Intern Med, 158, p. 2200-11
- (2001) "Product Information. Precedex (dexmedetomidine)." Abbott Pharmaceutical
- (2001) "Product Information. Trileptal (oxcarbazepine)." Novartis Pharmaceuticals
- Ferslew KE, Hagardorn AN, McCormick WF (1990) "A fatal interaction of methocarbamol and ethanol in an accidental poisoning." J Forensic Sci, 35, p. 477-82
- Plushner SL (2000) "Valerian: valeriana officinalis." Am J Health Syst Pharm, 57, p. 328-35
- (2002) "Product Information. Xatral (alfuzosin)." Sanofi-Synthelabo Canada Inc
- (2002) "Product Information. Lexapro (escitalopram)." Forest Pharmaceuticals
- Cerner Multum, Inc. "UK Summary of Product Characteristics."
- Cerner Multum, Inc. "Australian Product Information."
- (2012) "Product Information. Fycompa (perampanel)." Eisai Inc
- (2014) "Product Information. Belsomra (suvorexant)." Merck & Co., Inc
- (2015) "Product Information. Rexulti (brexpiprazole)." Otsuka American Pharmaceuticals Inc
diphenhydrAMINE levodopa
Applies to: Respa C&C (acetaminophen / dextromethorphan / diphenhydramine / phenylephrine) and levodopa
MONITOR: Anticholinergic agents may decrease the absorption and oral bioavailability of levodopa. The proposed mechanism involves increased gastrointestinal transit time due to reduction of stomach and intestinal motility by anticholinergic agents, thereby increasing the gastric degradation of levodopa and reducing the amount available for absorption in the small intestine. In one study, pretreatment with trihexyphenidyl decreased the peak plasma concentration (Cmax) and delayed the time to peak concentration (Tmax) of levodopa in 3 of 6 healthy volunteers and 4 of 6 Parkinson patients. In another study, 42% of patients receiving levodopa with anticholinergic therapy developed abnormal involuntary movements compared to 19% of those treated with levodopa alone. Discontinuation or dosage reduction of anticholinergic therapy resulted in disappearance or amelioration of the symptoms in 9 of 10 cases, although subsequent aggravation of Parkinsonism necessitated resumption of anticholinergic therapy in 5 cases. There is also a case report describing a patient who required large doses of levodopa during concomitant therapy with homatropine. Following discontinuation of homatropine, the patient exhibited symptoms of levodopa toxicity and required a significant decrease in the levodopa dosage. Other studies have reported no effect of anticholinergic agents on levodopa blood levels or pharmacologic effects.
MANAGEMENT: Although certain anticholinergic agents may be used as adjunctive therapy in Parkinson's disease, clinicians should recognize their potential to reduce the oral bioavailability of levodopa in some patients. Pharmacologic response to levodopa should be monitored more closely whenever anticholinergic agents are added to or withdrawn from therapy, and the dosages of the drugs adjusted as necessary.
References
- Bergmann S, Curzon G, Friedel J, et al. (1974) "The absorption and metabolism of a standard oral dose of levodopa in patients with parkinsonism." Br J Clin Pharmacol, 1, p. 417-24
- Birket-Smith E (1974) "Abnormal involuntary movements induced by anticholinergic therapy." Acta Neurol Scand, 50, p. 801-11
- Rivera-Calimlim L, Dujovne CA, Morgan JP, Lasagna L, Bianchine JR (1971) "Absorption and metabolism of L-dopa by the human stomach." Eur J Clin Invest, 1, p. 313-20
- Algeri S, Cerletti C, Curcio M, et al. (1976) "Effect of anticholinergic drugs on gastro-intestinal absorption of L-dopa in rats and man." Eur J Pharmacol, 35, p. 293-9
- Fermaglich J, O'Dougherty DS (1972) "Effect of gastric motility on levodopa." Dis Nerv Syst, 33, p. 624-5
- Hughes R, Polgar JG, Weightman D, Walton JN (1971) "Levodopa in Parkinsonism: the effects of withdrawal of anticholinergic drugs." Br Med J, 2, p. 487-91
levodopa phenylephrine
Applies to: levodopa and Respa C&C (acetaminophen / dextromethorphan / diphenhydramine / phenylephrine)
GENERALLY AVOID: Coadministration with levodopa may potentiate the cardiovascular effects of sympathomimetic agents (e.g., epinephrine, norepinephrine, isoproterenol, amphetamine). Additive increases in blood pressure and heart rate may occur due to enhanced sympathetic activity. However, data evaluating the interaction are not available.
MANAGEMENT: The use of levodopa with sympathomimetic agents should generally be avoided. If concomitant use is required, close monitoring of the cardiovascular system is recommended and the dose of the sympathomimetic agent may need to be reduced.
References
- Cerner Multum, Inc. "UK Summary of Product Characteristics."
- Cerner Multum, Inc. "Australian Product Information."
Drug and food interactions
acetaminophen food
Applies to: Respa C&C (acetaminophen / dextromethorphan / diphenhydramine / phenylephrine)
GENERALLY AVOID: Chronic, excessive consumption of alcohol may increase the risk of acetaminophen-induced hepatotoxicity, which has included rare cases of fatal hepatitis and frank hepatic failure requiring liver transplantation. The proposed mechanism is induction of hepatic microsomal enzymes during chronic alcohol use, which may result in accelerated metabolism of acetaminophen and increased production of potentially hepatotoxic metabolites.
MANAGEMENT: In general, chronic alcoholics should avoid regular or excessive use of acetaminophen. Alternative analgesic/antipyretic therapy may be appropriate in patients who consume three or more alcoholic drinks per day. However, if acetaminophen is used, these patients should be cautioned not to exceed the recommended dosage (maximum 4 g/day in adults and children 12 years of age or older).
References
- Kaysen GA, Pond SM, Roper MH, Menke DJ, Marrama MA (1985) "Combined hepatic and renal injury in alcoholics during therapeutic use of acetaminophen." Arch Intern Med, 145, p. 2019-23
- O'Dell JR, Zetterman RK, Burnett DA (1986) "Centrilobular hepatic fibrosis following acetaminophen-induced hepatic necrosis in an alcoholic." JAMA, 255, p. 2636-7
- Seeff LB, Cuccherini BA, Zimmerman HJ, Adler E, Benjamin SB (1986) "Acetaminophen hepatotoxicity in alcoholics." Ann Intern Med, 104, p. 399-404
- Thummel KE, Slattery JT, Nelson SD (1988) "Mechanism by which ethanol diminishes the hepatotoxicity of acetaminophen." J Pharmacol Exp Ther, 245, p. 129-36
- McClain CJ, Kromhout JP, Peterson FJ, Holtzman JL (1980) "Potentiation of acetaminophen hepatotoxicity by alcohol." JAMA, 244, p. 251-3
- Kartsonis A, Reddy KR, Schiff ER (1986) "Alcohol, acetaminophen, and hepatic necrosis." Ann Intern Med, 105, p. 138-9
- Prescott LF, Critchley JA (1983) "Drug interactions affecting analgesic toxicity." Am J Med, 75, p. 113-6
- (2002) "Product Information. Tylenol (acetaminophen)." McNeil Pharmaceutical
- Whitcomb DC, Block GD (1994) "Association of acetaminopphen hepatotoxicity with fasting and ethanol use." JAMA, 272, p. 1845-50
- Bonkovsky HL (1995) "Acetaminophen hepatotoxicity, fasting, and ethanol." JAMA, 274, p. 301
- Nelson EB, Temple AR (1995) "Acetaminophen hepatotoxicity, fasting, and ethanol." JAMA, 274, p. 301
- Zimmerman HJ, Maddrey WC (1995) "Acetaminophen (paracetamol) hepatotoxicity with regular intake of alcohol: analysis of instances of therapeutic misadventure." Hepatology, 22, p. 767-73
dextromethorphan food
Applies to: Respa C&C (acetaminophen / dextromethorphan / diphenhydramine / phenylephrine)
GENERALLY AVOID: Alcohol may potentiate some of the pharmacologic effects of CNS-active agents. Use in combination may result in additive central nervous system depression and/or impairment of judgment, thinking, and psychomotor skills.
MANAGEMENT: Patients receiving CNS-active agents should be warned of this interaction and advised to avoid or limit consumption of alcohol. Ambulatory patients should be counseled to avoid hazardous activities requiring complete mental alertness and motor coordination until they know how these agents affect them, and to notify their physician if they experience excessive or prolonged CNS effects that interfere with their normal activities.
References
- Warrington SJ, Ankier SI, Turner P (1986) "Evaluation of possible interactions between ethanol and trazodone or amitriptyline." Neuropsychobiology, 15, p. 31-7
- Gilman AG, eds., Nies AS, Rall TW, Taylor P (1990) "Goodman and Gilman's the Pharmacological Basis of Therapeutics." New York, NY: Pergamon Press Inc.
- (2012) "Product Information. Fycompa (perampanel)." Eisai Inc
- (2015) "Product Information. Rexulti (brexpiprazole)." Otsuka American Pharmaceuticals Inc
levodopa food
Applies to: levodopa
GENERALLY AVOID: Alcohol may potentiate some of the pharmacologic effects of levodopa. Use in combination may result in additive central nervous system depression and/or impairment of judgment, thinking, and psychomotor skills.
MONITOR: Limited clinical data suggest that high protein content in the diet may reduce or cause fluctuations in the clinical response to oral and enteral formulations of levodopa in patients with Parkinson's disease. Proposed mechanisms include delayed gastric emptying, decreased levodopa absorption when taken with a protein rich diet, and competition with certain amino acids for transport across the gut wall and/or the blood brain barrier. Data have been conflicting. Clinical studies have variously reported no effect, reduced levodopa absorption with low-protein meals, reduced effects of oral and enteral formulations of levodopa with high daily protein intake, and no differences compared to fasting with high-protein meals. Neuroleptic malignant-like symptoms were reported in a patient with Parkinson's disease who was receiving pramipexole, entacapone, and immediate-release levodopa/carbidopa, after the protein content of his enteral feedings via nasogastric tube was increased from 0.88 g/kg/day to 1.8 g/kg/day; symptoms improved after the protein was reduced to 1 g/kg/day and bromocriptine was administered. Another patient receiving immediate-release carbidopa/levodopa, pramipexole, and entacapone experienced severe rigidity after initiation of continuous enteral nutrition via oral gastric tube containing 1.4 g/kg/day of protein; his Parkinsonian symptoms improved after the protein content was reduced to 0.9 g/kg/day, the feeding was changed to bolus feedings, and the levodopa was administered between boluses.
MANAGEMENT: In general, alcohol consumption should be avoided or limited during treatment with CNS-depressant agents. Until more data are available, it is advisable to avoid large fluctuations in daily protein intake and to monitor patients for altered effects of oral and enteral levodopa formulations if the protein content of the diet is increased.
References
- Cerner Multum, Inc. "UK Summary of Product Characteristics."
- Wohlt PD, Zheng L, Gunderson S, Balzar SA, Johnson BD, Fish JT (2009) "Recommendations for the use of medications with continuous enteral nutrition." Am J Health Syst Pharm, 66, p. 1438-67
- (2022) "Product Information. Duopa (carbidopa-levodopa)." AbbVie US LLC
- (2021) "Product Information. Duodopa (carbidopa-levodopa)." AbbVie Pty Ltd, 18
- (2023) "Product Information. Vyalev (foscarbidopa-foslevodopa)." AbbVie Corporation
- (2022) "Product Information. Dhivy (carbidopa-levodopa)." Avion Pharmaceuticals
diphenhydrAMINE food
Applies to: Respa C&C (acetaminophen / dextromethorphan / diphenhydramine / phenylephrine)
GENERALLY AVOID: Use of anticholinergic agents with alcohol may result in sufficient impairment of attention so as to render driving and operating machinery more hazardous. In addition, the potential for abuse may be increased with the combination. The mechanism of interaction is not established but may involve additive depressant effects on the central nervous system. No effect of oral propantheline or atropine on blood alcohol levels was observed in healthy volunteers when administered before ingestion of a standard ethanol load. However, one study found impairment of attention in subjects given atropine 0.5 mg or glycopyrrolate 1 mg in combination with alcohol.
MANAGEMENT: Alcohol should generally be avoided during therapy with anticholinergic agents. Patients should be counseled to avoid activities requiring mental alertness until they know how these agents affect them.
References
- Linnoila M (1973) "Drug effects on psychomotor skills related to driving: interaction of atropine, glycopyrrhonium and alcohol." Eur J Clin Pharmacol, 6, p. 107-12
levodopa food
Applies to: levodopa
ADJUST DOSING INTERVAL: The oral bioavailability and pharmacologic effects of levodopa and carbidopa may be decreased during concurrent administration with iron-containing products. The proposed mechanism is chelation of levodopa and carbidopa by the iron cation, forming an insoluble complex that is poorly absorbed from the gastrointestinal tract. In nine patients with Parkinson's disease, administration of levodopa-carbidopa 100 mg-25 mg with ferrous sulfate 325 mg decreased levodopa peak plasma concentration (Cmax) and systemic exposure (AUC) by 47% and 30%, respectively, and carbidopa Cmax and AUC by 77% and 82%, respectively, compared to administration with placebo. There was also evidence of reduced efficacy of levodopa in some patients. In another study consisting of eight healthy subjects, coadministration of levodopa 250 mg with ferrous sulfate 325 mg resulted in greater than 50% reductions in the Cmax and AUC of levodopa compared to administration of levodopa alone. The magnitude of the interaction was the greatest in patients whose plasma levels of levodopa were the highest following administration of levodopa alone.
MANAGEMENT: Until more information is available, patients receiving levodopa and/or carbidopa in combination with iron-containing products should be advised to separate the times of administration by as much as possible. Patients should be monitored for reduced efficacy of levodopa, and the dosage adjusted as necessary.
References
- Campbell NR, Hasinoff B (1989) "Ferrous sulfate reduces levodopa bioavailability: chelation as a possible mechanism." Clin Pharmacol Ther, 45, p. 220-5
- Campbell NR, Hasinoff BB (1991) "Iron supplements: a common cause of drug interactions." Br J Clin Pharmacol, 31, p. 251-5
- Campbell NR, Rankine D, Goodridge AE, Hasinoff BB, Kara M (1990) "Sinemet-ferrous sulphate interaction in patients with Parkinson's disease." Br J Clin Pharmacol, 30, p. 599-605
- Greene RJ, Hall AD, Hider RC (1990) "The interaction of orally administered iron with levodopa and methyldopa therapy." J Pharm Pharmacol, 42, p. 502-4
phenylephrine food
Applies to: Respa C&C (acetaminophen / dextromethorphan / diphenhydramine / phenylephrine)
MONITOR: Coadministration of two or more sympathomimetic agents may increase the risk of adverse effects such as nervousness, irritability, and increased heart rate. Central nervous system (CNS) stimulants, particularly amphetamines, can potentiate the adrenergic response to vasopressors and other sympathomimetic agents. Additive increases in blood pressure and heart rate may occur due to enhanced peripheral sympathetic activity.
MANAGEMENT: Caution is advised if two or more sympathomimetic agents are coadministered. Pulse and blood pressure should be closely monitored.
References
- Rosenblatt JE, Lake CR, van Kammen DP, Ziegler MG, Bunney WE Jr (1979) "Interactions of amphetamine, pimozide, and lithium on plasma norepineophrine and dopamine-beta-hydroxylase in schizophrenic patients." Psychiatry Res, 1, p. 45-52
- Cavanaugh JH, Griffith JD, Oates JA (1970) "Effect of amphetamine on the pressor response to tyramine: formation of p-hydroxynorephedrine from amphetamine in man." Clin Pharmacol Ther, 11, p. 656
- (2001) "Product Information. Adderall (amphetamine-dextroamphetamine)." Shire Richwood Pharmaceutical Company Inc
- (2001) "Product Information. Tenuate (diethylpropion)." Aventis Pharmaceuticals
- (2001) "Product Information. Sanorex (mazindol)." Novartis Pharmaceuticals
- (2001) "Product Information. Focalin (dexmethylphenidate)." Mikart Inc
- (2002) "Product Information. Strattera (atomoxetine)." Lilly, Eli and Company
Therapeutic duplication warnings
No 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.
See also
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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