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Research Article| Volume 14, ISSUE 4, P473-481, July 1996

Antiepileptic drug therapy: Clinical laboratory significance

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      Abstract

      When evaluating a patient who is taking an antiepileptic medication, it is important for the emergency physician to correlate the clinical presentation with the antiepileptic drug level. Therapeutic ranges have been suggested for most antiepileptic medications, but these must be interpreted in light of clinical efficacy and patient tolerance. When considering the efficacy of antiepileptic medications, it is necessary to consider the patient's unique metabolism, side-effect tolerance, and overall response to therapy. Suggested therapeutic ranges should be the first reference for the emergency physician. The purpose of this report is to discuss the laboratory values of commonly prescribed antiepileptic medications. Therapeutic ranges, side-effects, and common medication interactions are discussed concerning phenytoin, phenobarbital, carbamezapine, and valproic acid.

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      References

        • Kutt H
        • Penry JK
        Usefulness of blood levels of antiepileptic drugs.
        Arch Neurol. 1974; 31: 283-288
        • Kutt H.
        Therapeutic monitoring of antiepileptic drugs.
        in: Pedley TA Meldum BS Recent advances in epilepsy. Churchill-Livinston, New York1985: 183-205
        • French J
        The long term management of epilepsy.
        Ann Int Med. 1994; 120: 411-422
        • Livingstone S
        • Merman W
        • Pauli L
        Anticonvulsant drag blood levels, practical applications based on 12 years experience.
        JAMA. 1975; 232: 60-62
        • Theodore WH
        • Narang PK
        • Holmes MD
        • Reeves P
        • Nice FJ
        Carbamazepine and its epoxide: relation of plasma levels to toxicity and seizure control.
        Ann Neurol. 1989; 25: 194-196
        • Barre J
        • Didly F
        • Delion F
        • Tillement JP
        Problems in therapeutic drug monitoring: free drug level monitoring.
        Ther Drug Monit. 1988; 10: 133-143
        • Tozer TW
        Concepts basic to pharmacokinetics.
        Pharmacol Ther. 1981; 12: 109-131
        • Wilkinson GR
        • Shand DG
        A physiological approach to hepatic drug clearance.
        Clin Pharm Ther. 1975; 18 (89): 377
        • Chadwick D
        • Vydelingum C
        • Galbraith A
        • Reynolds EH
        The value of serum phenytoin levels in new referrals with epilepsy. One drug in the treatment of epilepsy.
        in: Gardner-Thorp C Janz D Munarri H Antiepileptic drug monitoring. Tunbridge Wells. Kent Pitman Medical, UK1977: 187-196
        • Dupuis RE
        • Mirando-Massari J
        Anticonvulsant: pharmacotherapeutic issues in the critically ill patients.
        AACN Clin Crit Care Nurs. 1991; 2: 639-656
        • Smith DB
        Antiepileptic drug selection in adults.
        in: Smith DB Epilepsy: current approaches to diagnosis and treatment. Raven Press, New York1990: 111-140
        • Gugler R
        • Manion CV
        • Azarnoff DL
        Phenytoin: pharmacokinetics and bioavailability.
        Clin Pharmacol Ther. 1976; 19: 135-142
        • Paxton JW
        • Rowell FJ
        • Ratcliff JG
        • et al.
        Salivary phenytoin radioimmunoassay. A simple method for assessment of protein bound drug concentrations.
        Eur J Clin Pharmacol. 1977; 11: 72-74
        • Penry J
        • Newmark M
        The use of antiepileptic drugs.
        Ann Int Med. 1979; 90: 207-218
        • Darcey BA
        • Solow EB
        • Pippenger CE
        Pippenger CE Penry JK Kutt H Gas liquid chromatographic quantitation of phenytoin, phenobarbital, primidone, and carbamazepine. Raven Press, New York1978: 67-74
        • Turnbull DM
        • Rawling MD
        • Weightmann D
        • Chadwick DW
        Therapeutic serum concentration of phenytoin: influence of sei zure type.
        J Neurol Neurosurg Psychiatry. 1984; 47: 231-234
        • Wallace SJ
        Anti-epileptic drug monitoring: an overview.
        Dev Med Child Neurol. 1990; 32: 923-926
        • Peterson GM
        • Khoo BHC
        • von Witt RJ
        Clinical response in epilepsy in relation to total and free serum levels of phenytoin.
        Therap Drug Monit. 1991; 13: 415-419
        • De Monaco JH
        • Lawless LM
        Variability of phenytoin protein binding in epileptic patients.
        Arch Neurol. 1983; 40: 481-483
        • Booker HE
        • Darcey B
        Serum concentration of free diphenylhydantoin and their relationship to clinical intoxication.
        Epilepsia. 1973; 14: 177-179
        • Baird-Lambert J
        • Manglick MP
        • Wale M
        • Buchanan N
        Identifying patients who might benefit from free-phenytoin monitoring.
        Ther Drug Monit. 1987; 9: 134-138
        • Kilpatrick LJ
        • Wanwimolruk S
        • Wing LMH
        Plasma concentrations of unbound phenytoin in the management of epilepsy.
        Br J Clin Pharmacol. 1984; 17: 539-546
        • Hooper WD
        • Bochner F
        • Eadie MJ
        • et al.
        Plasma protein binding of diphenylhydantoin effects of sex hormones, renal disease and hepatic disease.
        Clin Pharmacol Ther. 1974; 15: 276-282
        • Perucca E
        • Richens A
        • Ruprah M
        Serum protein binding of phenytoin in pregnant women.
        Br J Clin Pharm. 1981; 11: 409-410
        • Leonard RF
        • Knott PJ
        • Rankin GO
        • et al.
        Phenytoin-salicylate interaction.
        Clin Pharm Ther. 1981; 29: 56-60
        • Skovsted L
        • Kristensen M
        • Hansen JM
        • et al.
        The effect of different oral anticoagulants on diphenylhydantoin (DPH) and tolbutamide metabolism.
        Acta Med Scan. 1976; 199: 513-515
        • Miller RR
        • Porter J
        • Greenbelt DJ
        Clinical importance of the interaction of phenytoin and isoniazid.
        Chest. 1979; 75: 356-358
        • Sandor P
        • Sellars EM
        • Drumbnell M
        • Khouw V
        Effects of short and long term alcohol use on phenytoin kinetics in chronic alcoholics.
        Clin Pharmacother. 1981; 30: 390-397
        • Monks A
        • Boobis S
        • Wadsworth J
        • Richens A
        Plasma protein binding interactions between phenytoin and valproic acid in vitro.
        Br J Clin Pharmacol. 1978; 6: 487-492
        • Svendsen TL
        • Kristensen M
        • Hanse JM
        • Skovsted L
        The influence of disulfiram on the half-life and metabolic clearance rate of diphenylhydantoin and tolbutamide in man.
        Eur J Clin Pharmacol. 1976; 9: 439-441
        • Kay L
        • Kampmann JP
        • Svendsen TL
        • et al.
        Influence of rifampin and isoniazid on the kinetics of phenytoin metabolism.
        Br J Clin Pharmacol. 1985; 20: 323-326
        • Fraser DG
        • Ludden TM
        • Evens RP
        • Sutherland EW
        Displacement of phenytoin from plasma binding sites by salicylate.
        Clin Pharmacol Ther. 1980; 27: 165-169
        • Kutt H
        • Kutt HE
        Phenobarbital. Interactions with other drugs.
        in: Woodbury DM Penry JK Pippenger CE Antiepileptic drugs. 2nd edn. Raven Press, New York1982: 329-340
        • Kutt H
        Phenytoin. Interactions with other drugs.
        in: Levy RH Dreifuss FE Mattson RH Meldrum BS Penry J Antiepileptic drugs. 3rd edn. Raven Press, New York1989: 533-554
        • Perucca E
        • Hebdige S
        • Frigo GM
        • et al.
        Interaction between phenytoin and valproic acid: plasma protein binding and metabolic effects.
        Clin Pharmacol Ther. 1980; 28: 779-789
        • Koup JR
        Interaction of chloramphenicol with phenytoin and phenobarbital. A case report.
        Clin Pharmacol Ther. 1978; 24: 571-575
        • Algozzine GJ
        • Stewart RB
        • Springer PK
        Decreased clearance of phenytoin with cimetidine.
        Ann Int Med. 1981; 95: 244-245
        • Mellick LB
        • Morgan JA
        • Mellick GA
        Presentation of acute phenytoin overdose.
        Am J Emerg Med. 1989; 7: 61-67
        • Kutt H
        • Winters W
        • Kokenge R
        • McDowell R
        Dyskinesia induced by neuroleptics.
        J Neurol Neurosurg Psychiatry. 1976; 39: 1212-1218
        • Pugh CB
        • Garnett WR
        Current issues in the treatment of epilepsy.
        Clin Pharm. 1991; 10: 335-358
        • Leppik IE
        Phenytoin.
        in: Kutt H Resor Jr, SR Medical treatment of epilepsy. Marcell-Dekker, New York1992: 279-292
        • Trimble MR
        • Corbett JA
        Some somatic consequences of antiepileptic drugs.
        in: Oxley J Janz D Meinardi H Chronic toxicity of anti-epileptic drugs. Raven Press, New York1983: 201-204
        • Osorio I
        • Burnstine TH
        • Remler B
        • Manon-Espaillat R
        • Reed RC
        Phenytoin-induced seizures: a paradoxical effect at toxic concentrations in epileptic patients.
        Epilepsia. 1989; 30: 230-234
        • Levy LL
        • Fenichel GM
        Diphenylhydantoin activated seizures.
        Neurology (Minneap). 1965; 15: 716-722
        • Patel H
        • Crichton JV
        The neurologic hazards of diphenylhydantoin in childhood.
        J Pediatr. 1968; 73: 676-684
        • Troupin AS
        • Ojemann LM
        Paradoxical intoxication: a complication of anticonvulsant administration.
        Epilepsia. 1975; 16: 753-758
        • Stilman N
        • Masdeu JC
        Incidence of seizures with phenytoin toxicity.
        Neurology. 1985; 35: 1769-1772
        • Prince DA
        • Connors BW
        Mechanisms of interictal epileptogenesis.
        in: Delgado-Escueta AV Ward Jr, AA Basic mechanisms of the epilepsies: molecular and cellular approaches. Raven Press, New York1986: 275-299
        • Uthman B
        • Wilder B
        Emergency management of seizures: an overview.
        Epilepsia. 1989; 30: S33-S37
        • Earnest MP
        • Marx JA
        • Drury LR
        Complications of intravenous phenytoin for acute treatment of seizures: recommendations for usage.
        JAMA. 1983; 249: 762-765
        • Wilder BJ
        • Ramsay RE
        • Willmore JL
        • et al.
        Efficacy of intravenous phenytoin in the treatment of status epilepticus; kinetics of central nervous system penetrations.
        Ann Neurol. 1977; 1: 511-518
        • Rall TW
        • Schleifer LS
        Drugs effective in the therapy of the epilepsies.
        in: Gilman AG Rall TW Niew AS Goodman and Gilman's The pharmacological basis of therapeutics. 8th edn. McGraw Hill, New York1990: 436-462
        • Rambeck B
        • Boenigk HE
        • Dunlop A
        • et al.
        Predicting phenytoin dose—a revised nomogram.
        Ther Drug Monit. 1979; : 1325-1333
        • Painter MJ
        Phenobarbital: clinical use.
        in: Levy RH Dreifuss FE Mattson RH Antiepileptic drugs. 3rd edn. Raven Press, New York1989: 329-340
        • Gallagher BB
        Phenobarbital.
        in: Resor SR Kutt H The medical management of epilepsy. Marcell-Dekker, New York1992: 357-362
        • Greenberg MS
        revised edition. Handbook of neurosurgery. Greenberg Graphics, New York1990: 369-374
        • Ramsey RE
        • Hammond EF
        • Percalski RJ
        • et al.
        Brain uptake of phenytoin, phenobarbital and diazepam.
        Arch Neurol. 1979; 36: 535-539
        • Kutt H
        Interactions between anticonvulsants and other commonly prescribed drugs.
        Epilepsia. 1984; 25: S118-S131
        • Morselli PL
        • Rizzo M
        • Garattion S
        Interaction between phenobarbital and diphenylhydantoin in animals and epileptic patients.
        in: revised edition. Proc NY Acad Sci. 179. 1971: 88-107
        • Meindardi H
        Other antiepileptic drugs. Carbamazepine.
        in: Woodbury DM Penry JK Schmidt RP Antiepileptic drugs. Raven Press, New York1972: 487-496
        • Fisher RS
        • Cysk B
        Fatal overdose of carbamazepine: a case report and review of the literature.
        Clin Tox. 1988; 26: 477-481
        • Brodie MJ
        • MacPhee GJ
        Carbamazepine neurotoxicity precipitated by diltiazem.
        Br J Med. 1986; 292: 1170-1171
        • Dalton MJ
        • Powell JR
        • Messenheimer Jr, JA
        • Clark J
        Cimetidine and carbamazepine: a complex drug interaction.
        Epilepsia. 1986; 27: 553-558
        • MacPhee GJ
        • McInness GT
        • Thompson GGT
        • Brodie MJ
        Verapamil potentiates carbamazepine neurotoxicity: a clinically important inhibitory interaction.
        Lancet. 1986; 1: 700-703
        • Valsalan VL
        • Cooper GL
        Carbamazepine intoxication caused by interaction with isoniazid.
        Br Med J. 1982; 285: 261-262
        • Yu YL
        • Huang CJ
        • Chin D
        • Woo E
        • Chag CM
        Interaction between carbamazepine and dextropropoxyphene.
        Post Grad Med J. 1986; 62: 231-233
        • Zitelli BJ
        • Howrie DL
        • Altman H
        • Macoon TJ
        Erythromycin induced drug interactions: an illustrative case and review of the literature.
        Clin Pediatr. 1987; 26: 117-119
        • Browne TR
        Drug Therapy: Valproic acid.
        N Engl J Med. 1980; 302: 661-666
        • Covanis A
        • Gupta AK
        • Jeavons PM
        Sodium valproate: monotherapy and polytherapy.
        Epilepsia. 1982; 23: 693-720
        • Pinder RM
        • Brogden RN
        • Speight TM
        • Avery GS
        Sodium valproate: a review of its pharmacological properties and therapeutic efficacy in epilepsy.
        Drugs. 1977; 13: 81-123
        • Mattson R
        Valproic acid and management of seizures.
        in: revised edition. Current neurology. vol. 2. Houghton Mifflin, Boston1979: 229-248
        • Mattson R
        • Cramer JA
        • Williamson PD
        • Novelly RA
        Valproic acid in epilepsy: clinical and pharmacological effects.
        Ann Neurol. 1978; 3: 20-25
        • Brum J
        • Wilder BJ
        • Bauman AW
        • Willmore LJ
        Clinical efficacy and long term effects of valproic acid therapy on spike-and-wave discharges.
        Neurology (Minneap). 1980; 30: 42-46
        • Rowan AJ
        • Binnie CD
        • de Beer-Pawlikowski NK
        • Goedhoft DM
        • Gutter T
        • Vander Geest P
        Sodium valproate: serial monitoring of EEG and serum levels.
        Neurology. 1979; 29: 1450-1459
        • Schmidt D
        Adverse effects of valproate.
        Epilepsia. 1984; 25 (Suppl): S44-S49
        • Chadwick DW
        • Cumming WJK
        • Livingstone I
        • Cartlidge NEF
        Acute intoxication with sodium valproate.
        Ann Neurol. 1979; 6: 552-553
        • Keyser A
        • Hekster YA
        • Termond E
        • Theeuwes A
        • Schaap M
        • Rwiza HT
        Side effects of drugs in epileptic patients.
        Pharm Weekbl Sci. 1990; 12: 145-150
        • Murphy MJ
        • Lynon IW
        • Taylor JW
        • Mitts G
        Valproic acid induced pancreatitis in an adult (letter).
        Lancet. 1981; 1: 41-42