Epilepsia, 16~223-227,1975.
Raven Press, New York
Anticonvulsant Level in Saliva, Serum, and Cerebrospinal Fluid A. S. Troupin and P. Friel Department of Neurological Surgery, University of Washington School of Medicine, Seattle, Washington 981 95 (Received September 14,1974) INTRODUCTION The value of determining serum concentration of anticonvulsants for therapeutic and research purposes is. well established (Buchthal and Svensmark, 1959;Kutt et al., 1968;Eadie et al., 1973). The rationale for measuring total anticonvulsants in serum is the premise that unbound drug in serum is the active agent, and bound drug a reserve that helps dampen oscillations due to administration, excretion, etc. (Keen, 1971). Determination of free anticonvulsants in serum is a cumbersome method, requiring dialysis and ultracentrifugation (Conard et al., 1971), and then determination of minute quantities of drug in tiny samples. Nonetheless, measurement of free anticonvulsants in serum is probably preferable since the level is more closely related to toxic, and presumably t o therapeutic, effects than is the total concentration (Booker and Darcey, 1973). Since CSF is a nearly protein-free ultrafiltrate of serum, the concentration in CSF would give the same information (Triedman et al., 1960; Lund et al., 1972). Spinal puncture is, however, usually not indicated. Most of thii work concerns diphenylhydantoin. A more readily available body fluid in which free diphenylhydantoin can be measured is saliva (Bochner et al., 1974). We report here determinations of drugs in simultaneously
obtained saliva, CSF, and serum: diphenylhydantoin (Dilantina, Parke Davis), mbamazepine (Tegretol@, Ciba-Geigy), phenobarbital, and primidone (Mysoline@,Ayerst). METHODS
The 8 adult patients, who were on anticonvulsant medication in several combinations, needed lumbar puncture, pneumoencephalography,or both. No patient had acute infectious disease, recent head trauma, or subarachnoid hemorrhage. Ten ml of CSF was withdrawn and several min later 10 ml of venous blood. Several minutes before or after lumbar puncture, 10 ml of saliva was collected, salivary flow being stimulated when the patients chewed a small block of paraffin (candle wax). Each specimen of saliva was centrifuged to separate mucous, cellular debris, and flecks of paraffii from the supernatant saliva. All determinations of anticonvulsant levels were performed by gas-liquid chromatography. Diphenylhydantoin, phenobarbital, and primidone were measured by our modification of the MacGee method-(Friel and Troupin, in press), and carbamazepine by the method of Green et al. (1973). Gas-liquid chromatography is a reliable method to determine small amounts of anticonvulsants in saliva and spinal fluid (Berlin et al., 1972;Bochner et al., 1974). To measure free anticonvulsants in serum, 1 ml of plasma was dialyzed to equilibrium (4hr) Key words: Anticonuulsanfs - CSF -Saliva - Unbound drug - diphenylhydantoin - (Bock, 1972) in a Plexiglas multicavity (Dilantina) - carbamazepine (Tegretola) equilibrium dialysis cell (Lab Apparatus Co., 223
A. S. TROWINAND P.FRIEL
224
Cleveland, Ohio) for 4 hr at 37OC in a reciprocating water bath. “Spectrapor” membrane tubing, with a 12,000- to 14,000-dalton molecular weight cutoff, was used. Free anticonvulsants were then determined by gas-liquid chromatography.
Primidone was determined in simultaneously obtained samples of saliva, CSF, and serum dialyzate in 3 patients (Table l), and in all the level was highest in saliva, with roughly similar levels in CSF and dialyzed serum. Total primidone levels were 9.5 to 15.0 pglml.
RESULTS
DISCUSSION
The percent of free anticonvulsant in each biological pool-dialyzed serum (unbound in serum), CSF, and salivais given in Table 1. The mean concentration of diphenylhydantoin was the same in saliva, CSF, and unbound in serum. In individual patients, too, levels in the three body fluids agreed well, sometimes to within 0.1 pg/ml, despite total levels from 6.5 to 45.5 pg/ml. The calculated agreement between CSF and dialyzate of serum was f 5.5%; between CSF and saliva, f 8.0%. The level of carbamazepine was the same in simultaneously drawn saliva, CSF, and protein free serum in 1 patient (Table 1). In other patients levels were measured in two body fluids rather than all three, and the results were very close. We consider the information on carbamazepine to suggest that it resembles diphenylhydantoin in that it occurs in the same concentration in saliva, CSF, and unbound in serum. The level of phenobarbital was the same in spinal fluid and unbound in serum, the calculated agreement being k 4%. Although the concentration in saliva was lower than in spinal fluid (Table l ) , the ratio of 1.6:l (SD 0.08) was fairly consistent in spinal fluid and saliva, but not sufficiently so to be of clinical value. Phenobarbital in saliva was less than the unbound drug in serum, and the ratio was not consistent. The level of total phenobarbital was 6.5 to 35.0 pg/ml.
Most of the diphenylhydantoin in serum is bound, with about 10% unbound or free (Triedman et al., 1960; Lunde et al., 1970; Lund et al., 1972; Eadie and Tyrer, 1973). Binding is temperature-dependent (Lunde et al., 1970), and 10% free diphenylhydantoin is obtained at 37OC, but the proportion of free diphenylhydantoin varies widely from one individual to another. The percent of free diphenylhydantoin is more closely related to clinical intoxication than the total level (Booker and Darcey, 1973). Bochner et aI. (1974) reported a close relation of free diphenylhydantoin in serum and of diphenylhydantoin in saliva, a finding we confirm in this study. The level of diphenylhydantoin in CSF, saliva, and unbound in serum is so close as t o make the level in saliva reliable for clinical use. The level of carbamazepine was also the same in all three body fluids in the 1patient in whom it was measured, and in other patients in whom it was measured in two rather than in three body fluids. About 50%of phenobarbital is bound (Eadie and Tyrer, 1973), the same proportion we found, and the level was the same in protein-free serum and in CSF in all our patients. There was less phenobarbital in saliva because phenobarbital is ionized at the pH of serum, and the ionized form does not readily diffuse across cell membranes to enter saliva (Maynert; 1972). Although the level of
TABLE 1. Percent o f total level o f anticonvulsant in dialyzed serum. CSF. and saliva Drugso
Diphenylhydantoin (6) Carbamazepine (1) Phenobarbital (8) Primidone (3)
Serum dialyzate10.0f 0.8 33 49.8 4.8 78.0 f 9.5
*
“No. of examinations in parentheses. is standard deviation of the mean.
*
CSF 9.9 k 1.7 33 48.1 k 4.3 69.3 5.5
*
Saliva 9.1 k 1.7 37 29.8 k 3.1 108 8.0
ANTICONWLSANTS IN SALIVA phenobarbital in saliva does not accurately reflect the concentration of free drug in serum and CSF, the level in saliva is two-thirds of free phenobarbital and might be useful as a rough guide on some occasions. The concentration of primidone in saliva was higher than in serum, and lowest in CSF, a finding for which we have no explanation. A level of prim"done in CSF of only two-thirds the level in serum is not in keeping with the findings of Gallagher and Baumel (1972).It is possible, in view of the inaccuracy in determining primidone by gas-liquid chromatography when there are other drugs in serum, that the levels were in fact not different from each other. It seems unlikely that the level of primidone in saliva will have any clinical value. Since the concentration of diphenylhydantoin, and presumably of carbamazepine, in saliva is a reliable measure of the free drug in spinal fluid and serum, determination of the level in saliva will .be a convenient tool to study intoxication (Booker and Darcey, 1973), paradoxical intoxication, and poor control of seizures in the face of supposedly adequate total levels. The method may make it easier to investigate episodes of acute intoxication that occur with illnesses, addition of other drugs, etc., since these episodes may be unrelated to change in total anticonvulsant level. Interaction of other drugs with diphenylhydantoin is due to alteration in protein binding by the other drug administered, whether it is an anticonvulsant or not (Hooper et al., 1973, 1974). Measurement of diphenylhydantoin in saliva should make it possible to monitor closely the level of diphenylhydantoin when new anticonvulsants are added.
225
accurately by gas-liquid chromatography, the technique is readily applicable for clinical and investigative purposes. The method will be especially helpful in management of patients poorly controlled or intoxicated despite total levels of drug in serum in the therapeutic and below the toxic range, since the level of free drug may deviate from mean values.
SUMMARY Levels of four anticonvulsant drugs were measured simultaneously in saliva, spinal fluid, and dialyzed serum, i.e., free drug in serum. The level of diphenylhydantoin and possibly of carbamazepine was the same in the three body fluids. The level of phenobarbital was the same in spinal fluid and dialyzed serum, but was lower in saliva. The level of primidone was different in each body fluid. The technique is simple (flow of saliva stimulated when the subject chews candle wax or Teflon) and will be useful to determine the level of free diphenylhydantoin and carbamazepine, which is more closely related to intoxication or drug failure than is the total level of drug.
RESUME
Le taux de quatre produits anticonvulsivants 6tait do& de facon simultan6e dans la d i v e , le LCR et le drum dialyJ (c'est ii dire que l'on avait le produit libre dans le s6rum). Le taux de diph6nylhydantoine et vraisemblablement de carbamaz6pine Btaient identiques dans ces 3 compartiments liquides. Le taux de ph6nobarbital h i t 6gal dans le LCR et le sQum dialyd, mais 6tait plus bas dans la salive. La quantit6 de primidone Qait diff6rente dam CONCLUSIONS chaque compartiment liquide consid6r6. La technique est simple: un flot de salive (obtenu The level of some anticonvulsants in human en faisant d c h e r de la cire de bougie ou de est u t i l i i pour d6terminer le taux de saliva, CSF, and unbound in serum was studied Teflon) diphenylhydantoine et de carbarnadpine libre, simultaneously. Saliva was stimulated when the qui est en relation plus 6troite avec l'intoxisubject chewed candle wax The three body cation ou lhefficacit6 thbapeutique que le fluids contained equal proportions of unbound taux total du produit. diphenylhydantoin, probably also of carba(C. A. Tassinari, Marseilles) mazepine. The level of phenobarbital was lower in saliva, higher and the same in CSF and serum. Primidone was not found in the same RESUMEN concentration in any fluid. Since saliva is easy Se han determinado 10s niveles simultaneos to collect, and the level can be measured de cuatro anticonvulsivantes en saliva, liquid0
A. S. TROUPIN AND P. FRIEL
226
cefalorraqurdeo y en suero dializado, es deck, droga libre en suero. Los niveles difenilhidantoina y posiblemente 10s de carbamazepina fueron idgnticos en 10s tres fluidos corporales. Los niveles de fenobarbital fueron iguales en el liquid0 cefalorraqurdeo y en el suero dializado, per0 m8s bajos en saliva. Los de primidona resultaron distintos en 10s tres fluidos. La tbnica es simple, consiguiendose la descarga de saliva mediante la masticacibn de Tefl6n o cera, y sersl satisfactoria para determinar el nivel de difenilhidantoina y carbamizepina libres, que representa un indice m8s representativo de intoxicacih o fracas0 terapefitico que el nivel total de la droga. (A. Portera Sanchez, Madrid)
ZUSAMMENFASSUNG Die Spiegel von 4 Antikonvulsiva wurden gleichzeitig im Speichel, in der Spinalfliissigkeit und im dialysierten Serum d. h. der freie Anteil des Medikaments im Serum bestimmt. Die Spiegel von Diphenylhydantoin und wahrscheinlich auch von Carbamazepin entsprachen sich in den 3 KSrperflksigkeiten. Der Spiegel des Phenobarbital in der Spinalfliissigkeit war der gleiche wie im ddysierten Serum; im Speichel war er jedoch niedriger. Primidone zeigte unterschiedliche Spiegel in jeder Fliissigkeit. Die Technik ist einfach. Der Speichelfluss wird stimuliert, wenn der Patient Wachs oder Teflon kaut. Es ist nutzlich, den Spiegel des freien Diphenylhydantoins und des Carbamazepin zu bestimmen, da er engere Beziehungen zur Intoxikation oder zum Versagen der Arzneimittelwirkung aufweist als die Gesamtkonzentrationen des Medikaments. (D. Scheffner, Heidelberg)
ACKNOWLEDGMENT
This study was supported by National Institutes of Health research contracts N01NS-0-2281and NS-04053. REFERENCES Berlin A, Agurell S, Borga 0, Lund L, and SjSqvist F. Micromethod for the determination of diphenylhydantoin in plasma and cerebrospinal fluid-A comparison between gas chromatographic and a spectrophotometric method. Scand J Clin Lab Invest 29: 218-287,1972. Bochner F, Hooper W, Sutherland JM, Eadie
MJ, and Tyrer JH. Diphenylhydantoin concentrations in saliva. Arch Neurol 31:57-59, 1974. Bock GW. Measurement of the levels of diphenylhydantoin and phenobarbital in patients with epilepsy. Master's Thesis, McGill University, Montreal, 1972. Booker HE and Darcey B. Serum concentrations of free diphenylhydantoin and their relationship to clinical intoxication. Epilepsia 14:177-184, 1973. Buchthal F and Svensmark 0. Aspects of the pharmacology of phenytoin (Dilantin) and phenobarbital relevant to their dosage in the treatment of epilepsy. Epilepsia 1 :373-384, 1959. Conard GJ, Haarik CO, and Finger KF. Binding of 5, 5-diphenylhydantoin and its major metabolite to human and rat plasma' proteins. J Pharm Sci 60:1642-1646, 1971. Eadie MJ and Tyrer JH. Plasma levels of anticonvulsants. Aust NZ J Med 3:290-303, 1973. Friel P and Troupin AS. Flash heater ethylation of some antiepileptic drugs. Clin Chem (in press). Gallagher BB and Baumel IP. Primidone: Absorption, distribution, and excretion. In: DM Woodbury, J K Penry, and Schmidt FtP (Eds), Antiepileptic Drugs. Raven Press, New York, 1972, pp 357-360. Green JR, Friel P, and Amick-Corkill JA. Methods of gas-liquid chromatographic determinations of carbamazepine, phenytoin, phenobarbitone, and primidone. Clinical applications of serum level determinations of sulthiame and phenytoin. In: JWA Meijer, H Meinardi, C Gardner-.Thorpe, and E van der Kleijn (Eds), Methods of Analysis of Anti-Epileptic Drugs. Excerpta Medica, Amsterdam, 1973, pp 176-189. Hooper WD, Bochner F, Eadie MJ, and Tyrer JH. Plasma protein binding of diphenylhydantoin: Effects of sex hormones, renal and hepatic disease. Clin Pharmacol Ther 15:276-282,1974. Hooper WD, Sutherland JM, Bochner F, Tyrer JH, and Eadie MJ. The effects of certain drugs on the plasma protein binding of phenytoin. Aust NZ JMed 3:377-381,1973. Keen P. Effect of binding to plasma proteins on t h e distribution, activity, and elimination of drugs. In: B Brodie and N Gillette (Eds), Handbook o f Experimpntal Pharmacology 28:Part 1,1971. Springer-Verlag,Berlin. Kutt H and McDowell F. Management of epilepsy with diphenylhydantoin sodium. JAMA 203:167-170,1968. Lund L, Berlin A, and Lunde PKM. Plasma protein binding of diphenylhydantoin in patients with epilepsy: Agreement between the unbound fraction in plasma and the concentration in the cerebrospinal fluid. Clin Pharmacol Ther 13:196 200,1972.
ANTICONVULSANTS IN SALIVA Lunde PKM, W e A, Yaffe SJ, Lund L, and Sjoqvist F. Plasma protein binding of diphenylhydantoin in man: Interaction with other drugs and the effect of temperature and plasma dilution. Clin Pharmacol Ther 11:846-855,1970. Maynert EW. Phenobarbital, mephobarbital, and metharbital: Absorption, distribution,
227
and excretion. In: DM Woodbury, JK Penry, and RP Schmidt (Eds), Antiepileptic Drugs. Raven Press, New York, 1972, pp 303-310. Triedman HM, Fishman RA, and Yahr MD. Determination of plasma and cerebrospinal fluid levels of dilantin in the human. Trans A m Neurol Assoc 85:166 170,1960.
Raven Press, New York
Anticonvulsant Level in Saliva, Serum, and Cerebrospinal Fluid A. S. Troupin and P. Friel Department of Neurological Surgery, University of Washington School of Medicine, Seattle, Washington 981 95 (Received September 14,1974) INTRODUCTION The value of determining serum concentration of anticonvulsants for therapeutic and research purposes is. well established (Buchthal and Svensmark, 1959;Kutt et al., 1968;Eadie et al., 1973). The rationale for measuring total anticonvulsants in serum is the premise that unbound drug in serum is the active agent, and bound drug a reserve that helps dampen oscillations due to administration, excretion, etc. (Keen, 1971). Determination of free anticonvulsants in serum is a cumbersome method, requiring dialysis and ultracentrifugation (Conard et al., 1971), and then determination of minute quantities of drug in tiny samples. Nonetheless, measurement of free anticonvulsants in serum is probably preferable since the level is more closely related to toxic, and presumably t o therapeutic, effects than is the total concentration (Booker and Darcey, 1973). Since CSF is a nearly protein-free ultrafiltrate of serum, the concentration in CSF would give the same information (Triedman et al., 1960; Lund et al., 1972). Spinal puncture is, however, usually not indicated. Most of thii work concerns diphenylhydantoin. A more readily available body fluid in which free diphenylhydantoin can be measured is saliva (Bochner et al., 1974). We report here determinations of drugs in simultaneously
obtained saliva, CSF, and serum: diphenylhydantoin (Dilantina, Parke Davis), mbamazepine (Tegretol@, Ciba-Geigy), phenobarbital, and primidone (Mysoline@,Ayerst). METHODS
The 8 adult patients, who were on anticonvulsant medication in several combinations, needed lumbar puncture, pneumoencephalography,or both. No patient had acute infectious disease, recent head trauma, or subarachnoid hemorrhage. Ten ml of CSF was withdrawn and several min later 10 ml of venous blood. Several minutes before or after lumbar puncture, 10 ml of saliva was collected, salivary flow being stimulated when the patients chewed a small block of paraffin (candle wax). Each specimen of saliva was centrifuged to separate mucous, cellular debris, and flecks of paraffii from the supernatant saliva. All determinations of anticonvulsant levels were performed by gas-liquid chromatography. Diphenylhydantoin, phenobarbital, and primidone were measured by our modification of the MacGee method-(Friel and Troupin, in press), and carbamazepine by the method of Green et al. (1973). Gas-liquid chromatography is a reliable method to determine small amounts of anticonvulsants in saliva and spinal fluid (Berlin et al., 1972;Bochner et al., 1974). To measure free anticonvulsants in serum, 1 ml of plasma was dialyzed to equilibrium (4hr) Key words: Anticonuulsanfs - CSF -Saliva - Unbound drug - diphenylhydantoin - (Bock, 1972) in a Plexiglas multicavity (Dilantina) - carbamazepine (Tegretola) equilibrium dialysis cell (Lab Apparatus Co., 223
A. S. TROWINAND P.FRIEL
224
Cleveland, Ohio) for 4 hr at 37OC in a reciprocating water bath. “Spectrapor” membrane tubing, with a 12,000- to 14,000-dalton molecular weight cutoff, was used. Free anticonvulsants were then determined by gas-liquid chromatography.
Primidone was determined in simultaneously obtained samples of saliva, CSF, and serum dialyzate in 3 patients (Table l), and in all the level was highest in saliva, with roughly similar levels in CSF and dialyzed serum. Total primidone levels were 9.5 to 15.0 pglml.
RESULTS
DISCUSSION
The percent of free anticonvulsant in each biological pool-dialyzed serum (unbound in serum), CSF, and salivais given in Table 1. The mean concentration of diphenylhydantoin was the same in saliva, CSF, and unbound in serum. In individual patients, too, levels in the three body fluids agreed well, sometimes to within 0.1 pg/ml, despite total levels from 6.5 to 45.5 pg/ml. The calculated agreement between CSF and dialyzate of serum was f 5.5%; between CSF and saliva, f 8.0%. The level of carbamazepine was the same in simultaneously drawn saliva, CSF, and protein free serum in 1 patient (Table 1). In other patients levels were measured in two body fluids rather than all three, and the results were very close. We consider the information on carbamazepine to suggest that it resembles diphenylhydantoin in that it occurs in the same concentration in saliva, CSF, and unbound in serum. The level of phenobarbital was the same in spinal fluid and unbound in serum, the calculated agreement being k 4%. Although the concentration in saliva was lower than in spinal fluid (Table l ) , the ratio of 1.6:l (SD 0.08) was fairly consistent in spinal fluid and saliva, but not sufficiently so to be of clinical value. Phenobarbital in saliva was less than the unbound drug in serum, and the ratio was not consistent. The level of total phenobarbital was 6.5 to 35.0 pg/ml.
Most of the diphenylhydantoin in serum is bound, with about 10% unbound or free (Triedman et al., 1960; Lunde et al., 1970; Lund et al., 1972; Eadie and Tyrer, 1973). Binding is temperature-dependent (Lunde et al., 1970), and 10% free diphenylhydantoin is obtained at 37OC, but the proportion of free diphenylhydantoin varies widely from one individual to another. The percent of free diphenylhydantoin is more closely related to clinical intoxication than the total level (Booker and Darcey, 1973). Bochner et aI. (1974) reported a close relation of free diphenylhydantoin in serum and of diphenylhydantoin in saliva, a finding we confirm in this study. The level of diphenylhydantoin in CSF, saliva, and unbound in serum is so close as t o make the level in saliva reliable for clinical use. The level of carbamazepine was also the same in all three body fluids in the 1patient in whom it was measured, and in other patients in whom it was measured in two rather than in three body fluids. About 50%of phenobarbital is bound (Eadie and Tyrer, 1973), the same proportion we found, and the level was the same in protein-free serum and in CSF in all our patients. There was less phenobarbital in saliva because phenobarbital is ionized at the pH of serum, and the ionized form does not readily diffuse across cell membranes to enter saliva (Maynert; 1972). Although the level of
TABLE 1. Percent o f total level o f anticonvulsant in dialyzed serum. CSF. and saliva Drugso
Diphenylhydantoin (6) Carbamazepine (1) Phenobarbital (8) Primidone (3)
Serum dialyzate10.0f 0.8 33 49.8 4.8 78.0 f 9.5
*
“No. of examinations in parentheses. is standard deviation of the mean.
*
CSF 9.9 k 1.7 33 48.1 k 4.3 69.3 5.5
*
Saliva 9.1 k 1.7 37 29.8 k 3.1 108 8.0
ANTICONWLSANTS IN SALIVA phenobarbital in saliva does not accurately reflect the concentration of free drug in serum and CSF, the level in saliva is two-thirds of free phenobarbital and might be useful as a rough guide on some occasions. The concentration of primidone in saliva was higher than in serum, and lowest in CSF, a finding for which we have no explanation. A level of prim"done in CSF of only two-thirds the level in serum is not in keeping with the findings of Gallagher and Baumel (1972).It is possible, in view of the inaccuracy in determining primidone by gas-liquid chromatography when there are other drugs in serum, that the levels were in fact not different from each other. It seems unlikely that the level of primidone in saliva will have any clinical value. Since the concentration of diphenylhydantoin, and presumably of carbamazepine, in saliva is a reliable measure of the free drug in spinal fluid and serum, determination of the level in saliva will .be a convenient tool to study intoxication (Booker and Darcey, 1973), paradoxical intoxication, and poor control of seizures in the face of supposedly adequate total levels. The method may make it easier to investigate episodes of acute intoxication that occur with illnesses, addition of other drugs, etc., since these episodes may be unrelated to change in total anticonvulsant level. Interaction of other drugs with diphenylhydantoin is due to alteration in protein binding by the other drug administered, whether it is an anticonvulsant or not (Hooper et al., 1973, 1974). Measurement of diphenylhydantoin in saliva should make it possible to monitor closely the level of diphenylhydantoin when new anticonvulsants are added.
225
accurately by gas-liquid chromatography, the technique is readily applicable for clinical and investigative purposes. The method will be especially helpful in management of patients poorly controlled or intoxicated despite total levels of drug in serum in the therapeutic and below the toxic range, since the level of free drug may deviate from mean values.
SUMMARY Levels of four anticonvulsant drugs were measured simultaneously in saliva, spinal fluid, and dialyzed serum, i.e., free drug in serum. The level of diphenylhydantoin and possibly of carbamazepine was the same in the three body fluids. The level of phenobarbital was the same in spinal fluid and dialyzed serum, but was lower in saliva. The level of primidone was different in each body fluid. The technique is simple (flow of saliva stimulated when the subject chews candle wax or Teflon) and will be useful to determine the level of free diphenylhydantoin and carbamazepine, which is more closely related to intoxication or drug failure than is the total level of drug.
RESUME
Le taux de quatre produits anticonvulsivants 6tait do& de facon simultan6e dans la d i v e , le LCR et le drum dialyJ (c'est ii dire que l'on avait le produit libre dans le s6rum). Le taux de diph6nylhydantoine et vraisemblablement de carbamaz6pine Btaient identiques dans ces 3 compartiments liquides. Le taux de ph6nobarbital h i t 6gal dans le LCR et le sQum dialyd, mais 6tait plus bas dans la salive. La quantit6 de primidone Qait diff6rente dam CONCLUSIONS chaque compartiment liquide consid6r6. La technique est simple: un flot de salive (obtenu The level of some anticonvulsants in human en faisant d c h e r de la cire de bougie ou de est u t i l i i pour d6terminer le taux de saliva, CSF, and unbound in serum was studied Teflon) diphenylhydantoine et de carbarnadpine libre, simultaneously. Saliva was stimulated when the qui est en relation plus 6troite avec l'intoxisubject chewed candle wax The three body cation ou lhefficacit6 thbapeutique que le fluids contained equal proportions of unbound taux total du produit. diphenylhydantoin, probably also of carba(C. A. Tassinari, Marseilles) mazepine. The level of phenobarbital was lower in saliva, higher and the same in CSF and serum. Primidone was not found in the same RESUMEN concentration in any fluid. Since saliva is easy Se han determinado 10s niveles simultaneos to collect, and the level can be measured de cuatro anticonvulsivantes en saliva, liquid0
A. S. TROUPIN AND P. FRIEL
226
cefalorraqurdeo y en suero dializado, es deck, droga libre en suero. Los niveles difenilhidantoina y posiblemente 10s de carbamazepina fueron idgnticos en 10s tres fluidos corporales. Los niveles de fenobarbital fueron iguales en el liquid0 cefalorraqurdeo y en el suero dializado, per0 m8s bajos en saliva. Los de primidona resultaron distintos en 10s tres fluidos. La tbnica es simple, consiguiendose la descarga de saliva mediante la masticacibn de Tefl6n o cera, y sersl satisfactoria para determinar el nivel de difenilhidantoina y carbamizepina libres, que representa un indice m8s representativo de intoxicacih o fracas0 terapefitico que el nivel total de la droga. (A. Portera Sanchez, Madrid)
ZUSAMMENFASSUNG Die Spiegel von 4 Antikonvulsiva wurden gleichzeitig im Speichel, in der Spinalfliissigkeit und im dialysierten Serum d. h. der freie Anteil des Medikaments im Serum bestimmt. Die Spiegel von Diphenylhydantoin und wahrscheinlich auch von Carbamazepin entsprachen sich in den 3 KSrperflksigkeiten. Der Spiegel des Phenobarbital in der Spinalfliissigkeit war der gleiche wie im ddysierten Serum; im Speichel war er jedoch niedriger. Primidone zeigte unterschiedliche Spiegel in jeder Fliissigkeit. Die Technik ist einfach. Der Speichelfluss wird stimuliert, wenn der Patient Wachs oder Teflon kaut. Es ist nutzlich, den Spiegel des freien Diphenylhydantoins und des Carbamazepin zu bestimmen, da er engere Beziehungen zur Intoxikation oder zum Versagen der Arzneimittelwirkung aufweist als die Gesamtkonzentrationen des Medikaments. (D. Scheffner, Heidelberg)
ACKNOWLEDGMENT
This study was supported by National Institutes of Health research contracts N01NS-0-2281and NS-04053. REFERENCES Berlin A, Agurell S, Borga 0, Lund L, and SjSqvist F. Micromethod for the determination of diphenylhydantoin in plasma and cerebrospinal fluid-A comparison between gas chromatographic and a spectrophotometric method. Scand J Clin Lab Invest 29: 218-287,1972. Bochner F, Hooper W, Sutherland JM, Eadie
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