Carbamazepine-valnoctamide interaction in epileptic patients: in vitro/in vivo correlation

Six patients stabilized with carbamazepine (CBZ) therapy received an 8-day "add-on" supplement of valnoctamide (VCD), a tranquilizer available over the counter (OTC) in several European countries that exhibits promising anticonvulsant activity in animal models. During VCD intake, serum levels of the active CBZ metabolite, carbamazepine-10,11-epoxide (CBZ-E), increased fivefold from 1.5 +/- 0.7 micrograms/ml at baseline to 7.4 +/- 4.4 micrograms/ml after 4 days of VCD therapy and 7.7 +/- 3.1 micrograms/ml after 7 days of VCD therapy (means +/- SD, p < 0.01). In 4 patients, the increase in serum CBZ-E levels was associated with clinical signs of CBZ intoxication. CBZ-E levels returned to baseline after VCD therapy was discontinued. Serum CBZ levels remained stable throughout the study. The interaction observed in this study is similar to that described in patients treated with CBZ and valpromide (VPD, an isomer of VCD). In a mechanistic study, therapeutic concentrations of VCD inhibited hydrolysis of styrene oxide in human liver microsome preparations. Thus, VCD is a potent inhibitor of microsomal epoxide hydrolase (IC50 15 microM). There was a striking similarity between in vitro and in vivo inhibition potencies. In this study, VCD clearance was higher in epileptic patients (treated with CBZ) than in healthy subjects.

Carbamazepine coadministration with fluoxetine or fluvoxamine

To study the potential interaction between carbamazepine (CBZ) and selective serotonin reuptake inhibitors, fluoxetine (20 mg/day) and fluvoxamine (100 mg/day) were administered for 3 weeks to eight and seven epileptic patients, respectively, on chronic CBZ treatment. No significant changes in steady-state plasma concentrations of CBZ and its active metabolite, carbamazepine-10,11-epoxide (CBZ-E) occurred, suggesting that CBZ metabolism is probably not affected by fluoxetine or fluvoxamine administration.

A liquid chromatographic assay using a high-speed column for the determination of lamotrigine, a new antiepileptic drug, in human plasma

A sensitive, specific and rapid liquid-chromatographic method for the determination of the new antiepileptic drug lamotrigine (LTG) in human plasma is described. The method involves the use of a commercially available 3-microns particle size normal-phase column and a microflow-cell-equipped ultraviolet detector. Extraction is carried out with ethyl acetate after alkalinization on a 100-microliters plasma sample containing LTG and 3,5-diamino-6-(2-methoxyphenyl)-1,2,4-triazine as internal standard. The residue is reconstituted with 50 microliters of ethanol, and 5 microliters of the final solution is injected into the column. Elution is carried out at 35 degrees C using n-hexane/absolute ethanol/35% ammonia (80/20/0.25 by volume) as mobile phase at a flow rate of 2.0 ml/min. Detection is at 313 nm. The chromatographic separation requires < 3 min and the sensitivity limit is < 0.1 mg/L. Recovery is 88-96.2%, whereas within-day and day-to-day coefficients of variation are between 4.1 and 7.7%.

Possible severe thrombocytopenia associated with a single dose of plicamycin

OBJECTIVE

To report a case of possible severe thrombocytopenia associated with administration of a single dose of plicamycin.

CASE SUMMARY

A 73-year-old man with prostate cancer was admitted to the hospital with hypercalcemia (total serum calcium concentration 4.02 mmol/L) and a low baseline platelet count (152 x 10(9)/L). Because of his symptomatic hypercalcemia, he was treated with NaCl 0.9%, furosemide, oral inorganic phosphate, and a single dose of plicamycin (15 micrograms/kg). Five days after plicamycin administration his platelet count decreased to 52 x 10(9)/L, and continued to decrease further even after the transfusion of four units of platelets to a nadir of 7 x 10(9)/L (hospital day 20). A second transfusion produced a small increase in his platelet count. The patient's clinical status continued to deteriorate, however, and he subsequently died.

DISCUSSION

Plicamycin and other drugs that may induce thrombocytopenia are reviewed. The time course between plicamycin administration and the development of thrombocytopenia in our patient is assessed. Other contributing factors such as a low baseline platelet count and advanced age are also addressed.

CONCLUSIONS

It is likely that the severe thrombocytopenia experienced by our patient was caused by a single dose of plicamycin. Adjusting the dosage for a patient's renal function as well as close monitoring of the platelet count are necessary when administering this drug. We report this case to remind clinicians of the potential for the development of severe thrombocytopenia following administration of a single dose of plicamycin.

Impairment of carbamazepine-10, 11-epoxide elimination by valnoctamide, a valpromide isomer, in healthy subjects

The effect of the valpromide isomer valnoctamide (VCD, 200 mg three times daily for 8 days), an over-the-counter tranquillizer, on the elimination kinetics of a single oral dose of carbamazepine-10, 11-epoxide (CBZ-E, 100 mg) was investigated in healthy subjects. During VCD treatment, the half-life of CBZ-E was prolonged significantly compared with control (19.7 +/- 6.7 h vs 6.9 +/- 2.0 h, means +/- s.d., P less than 0.01), and its oral clearance decreased four-fold (from 109.6 +/- 30.7 to 28.8 +/- 11.1 ml h-1 kg-1, P less than 0.01). These findings indicate that VCM, like valpromide, strongly inhibits epoxide hydrolase in vivo.

Elevation of plasma phenytoin by viloxazine in epileptic patients: a clinically significant drug interaction

The effect of viloxazine (150-300 mg daily for 21 days) on plasma phenytoin levels at steady state was examined in 10 epileptic patients stabilised on a fixed phenytoin dosage. After starting viloxazine treatment, plasma phenytoin concentrations increased by 37% on average (range 7-94%) from a mean value of 18.8 micrograms/ml at baseline to a mean value of 25.7 micrograms/ml during the last week of combined therapy. In four patients the rise in plasma phenytoin was associated with the development of signs of phenytoin toxicity. Discontinuation of viloxazine resulted in return of plasma phenytoin towards baseline values and disappearance of the clinical symptoms. The mechanism of interaction probably involves inhibition of phenytoin metabolism by viloxazine. Careful monitoring of plasma phenytoin levels is recommended in patients treated with phenytoin who need to be started on viloxazine therapy.

Oral contraceptive drug interactions: important considerations

Interactions with oral contraceptives (OCs) occur with drugs commonly used to treat epilepsy, tuberculosis, and depression. Most women are more likely to use antibiotics, analgesics, and antihistamines, which have also been shown to interact with OCs. The mechanisms behind these interactions may be hepatic microsomal enzyme induction or inhibition, interference with the enterohepatic circulation of steroid metabolites, interference with absorption, competition between two drugs for the same metabolizing enzyme, or induction of an opposite physiologic effect. Rifampin was the first drug reported to interfere with the efficacy of OCs. The anticonvulsants and certain antibiotics, namely ampicillin and tetracycline, also decrease the efficacy of OCs. Oral contraceptives also interfere with the metabolism of other drugs. Plasma concentrations of theophylline, diazepam, and certain other benzodiazepines are increased by OC steroids. Because OCs interact with a wide variety of prescription and over-the-counter medications, a thorough drug history should be taken in all patients taking OCs.

Effect of phenobarbital on the pharmacokinetics of carbamazepine-10,11-epoxide, an active metabolite of carbamazepine

The single oral dose kinetics of carbamazepine-10,11-epoxide (CBZ-E), the active metabolite of carbamazepine, were studied in six epileptic patients, stabilized on phenobarbital (PB) monotherapy, and in six drug-free health volunteers. The epoxide metabolite was administered as an enteric-coated tablet at the dose of 200 mg to the patients and at the dose of 100 mg to the volunteers. Patients had a significantly higher plasma clearance of CBZ-E than the control group (mean values +/- SD = 220.2 +/- 63.5 versus 112.5 +/- 46.0 ml/h/kg, p less than 0.007) and a significantly shorter plasma half-life (mean values +/- SD = 4.3 +/- 1.0 versus 6.7 +/- 0.8 h, p less than 0.0015). These results suggest that PB induces CBZ-E metabolism.

Successful treatment of neonatal Citrobacter freundii meningitis with ceftriaxone

Citrobacter meningitis is an uncommon enteric gram-negative infection that afflicts neonates and young children. Approximately 30 percent of children treated or untreated die from the infection. We report a case of C. freundii meningitis that was resistant to ampicillin and was successfully treated with ceftriaxone, a third-generation cephalosporin. A 13-day-old, full-term baby was admitted to the hospital with a one-day history of fever up to 38.8 degrees C. On admission the infant had a temperature of 39.2 degrees C, pulse of 140 beats/min, and a respiratory rate of 32 breaths/min. Except for a slightly bulging fontanelle, the rest of the physical examination was within normal limits. Complete blood count revealed a white blood cell (WBC) count of 12.5 x 10(9)/L, with 0.66 polymorphonuclear cells, 0.10 bands, 0.18 lymphocytes, and 0.06 monocytes. A stat lumbar puncture showed 10 WBCs per high-power field with gram-negative rods. Empiric therapy with ampicillin 225 mg q12h and gentamicin 11 mg q8h was started. Both antibiotics were discontinued after culture and sensitivity results were positive for C. freundii in the blood and spinal fluid. The patient was successfully treated with nine days of ceftriaxone 250 mg q12h.

No effect of thioridazine on plasma concentrations of carbamazepine and its active metabolite carbamazepine-10,11-epoxide

The effect of an oral treatment with thioridazine (100 or 200 mg daily) on plasma concentrations of carbamazepine (CBZ) and its active metabolite carbamazepine-10,11-epoxide (CBZ-E) was studied in eight epileptic patients stabilized on CBZ therapy. No significant changes in steady-state plasma levels of CBZ and CBZ-E occurred, suggesting that CBZ metabolism is not apparently affected by thioridazine.

Interaction of carbamazepine-10,11-epoxide, an active metabolite of carbamazepine, with valproate: a pharmacokinetic study

The mechanism responsible for the valproate (VPA)-induced elevation of serum carbamazepine-10,11-epoxide (CBZ-E) levels was investigated in 6 normal subjects who received single oral doses of CBZ-E (100 mg) in a control session and during concurrent treatment with sodium VPA [500 mg twice daily (b.i.d.)]. VPA caused a significant prolongation of CBZ-E terminal half-life (t1/2 from 6.3 +/- 1.2 to 9.0 +/- 2.0 h, mean values +/- SD) and decreased CBZ-E clearance (from 90.6 +/- 18.8 to 63.2 +/- 16.1 ml h-1 kg-1, mean values +/- SD) without affecting CBZ-E apparent volume of distribution (from 0.82 +/- 0.19 to 0.81 +/- 0.24 l kg-1, mean values +/- SD). These findings indicate that VPA impairs the elimination of CBZ-E, presumably by inhibiting its metabolism.

Pilonidal sinus with an anal canal fistula. Report of a case

A rare case of a pilonidal cyst with the fistulous tract situated inside the anal canal is described. This is the sixth such case in the medical literature.

Evaluation of tricyclic antidepressant plasma levels by an automated enzyme immunoassay (EMIT) in comparison to a high-performance liquid chromatographic method

A new homogeneous enzyme immunoassay technique (EMIT) for the measurement of plasma levels of amitriptyline, nortriptyline, imipramine, and desipramine was used with an automated procedure and the results were compared to those of a high-performance liquid chromatographic (HPLC) method. Precision of the EMIT test was similar to that of the HPLC method with within-day coefficients of variation in the range of 3.9-10.9% (EMIT) and 3.9-9.6% (HPLC). The day-to-day coefficients of variation ranged from 4.4 to 11.7% for EMIT and from 6.1 to 8.4% for HPLC. Samples from 124 patients were analyzed by both methods and a good correlation was observed for all the four drugs. A paired t test indicated no significant difference for the EMIT and HPLC values. No significant interferences were observed between the tricyclics tested and other commonly associated drugs, such as benzodiazepines and neuroleptics. The new EMIT assay proved to be rapid and easy to perform and showed sufficient reliability and reproducibility to be used for either emergency or routine analysis.

Effect of valpromide on the pharmacokinetics of carbamazepine-10, 11-epoxide

The single oral dose pharmacokinetics of carbamazepine-10, 11-epoxide (CBZ-E) were investigated in six normal volunteers during a control session and during concurrent treatment with valpromide (VPM) (300 mg twice daily for 8 days). VPM caused a prolongation of the CBZ-E half-life from 6.4 +/- 1.4 to 20.5 +/- 6.3 h and decreased CBZ-E clearance from 73.5 +/- 20.0 to 23.5 +/- 4.0 ml h-1 kg-1 (P less than 0.01). These results suggest that the elevation of plasma CBZ-E levels in patients receiving carbamazepine and VPM in combination is due to inhibition of epoxide hydrolase in the liver.

Large-bowel transit in paraplegic patients

Severe constipation often follows spinal cord injury. The aim of this study was to evaluate transit of contents through the large bowel in patients with paraplegia after a complete transverse lesion of the spinal cord. Transit through the right colon, left colon, and rectum was evaluated in 11 patients (eight males, 3 females; 17 to 63 years old) and data were compared with that of 37 healthy control subjects. In all patients there was either no, or abnormally low, transit at the level of the left colon and rectum. A minor degree of transit delay at the level of the right colon was also present in eight patients. These data indicate that constipation in patients with paraplegia is due to abnormal transit, mainly at the level of the left colon and rectum, and transection of the spine between the C-4 and T-12 vertebral levels causes alteration of large-bowel motor activity mainly at the level of the segments innervated by the parasympathetic fibers of the sacral outflow.

Fab fragments in the treatment of digoxin overdose: pediatric considerations

Serious digoxin toxicity due to accidental or deliberate overdose is uncommon, but more than half of the cases reported in 1985 involved children. Toxicity can occur acutely, as with accidental overdose, or with long-term maintenance dosing. In children it is almost always acute. Conventional treatment includes gastric lavage or ipecac-induced emesis, and activated charcoal or nonabsorbable resins and cathartics to reduce absorption. Although children appear to tolerate massive ingestions without specific therapy, serum digoxin levels must be reduced quickly and safely when conventional measures have failed. Fab fragments of digoxin-specific antibodies have been successfully used to treat refractory digoxin toxicity. Indications for use should be limited to life-threatening digoxin toxicity when conventional therapy has failed.

An epidemiological study of the clinical impact of pharmacokinetic anticonvulsant drug interactions based on serum drug level analysis

The impact of pharmacokinetic anticonvulsant drug interactions on prescribing patterns and serum drug level distribution in a routine clinical setting was evaluated in a population of 848 patients chronically treated with phenytoin, phenobarbital, carbamazepine and valproic acid (either alone or as two-drug combinations) and referred for therapeutic drug monitoring for the first time. While dosages of each drug did not differ significantly between monotherapy and polytherapy patients, significant differences in serum level distribution were found. The proportion of patients with suboptimal serum carbamazepine and valproic acid levels (less than 4 and less than 50 micrograms/ml, respectively) was much greater in the polytherapy than in the monotherapy groups, probably as a consequence of induction of carbamazepine and valproic acid metabolism by combined anticonvulsants. Conversely, the proportion of phenobarbital levels above the upper limit of the optimal range (40 micrograms/ml) was greater among patients receiving phenytoin in combination than among patients taking phenobarbital alone, presumably as a result of phenytoin-induced inhibition of barbiturate metabolism. The therapeutic implications of these findings are discussed.

Carbamazepine-viloxazine interaction in patients with epilepsy

In six depressed epileptic patients stabilised on carbamazepine therapy, addition of the antidepressant agent viloxazine (300 mg/day for three weeks) induced a marked (average 55%) increase in steady-state plasma carbamazepine concentration. The concentration of the active metabolite carbamazepine-10,11-epoxide also increased during viloxazine therapy, but to a lesser extent (16%). In three patients, these effects were associated with symptoms of carbamazepine intoxication, which regressed rapidly when plasma carbamazepine and carbamazepine-10,11-epoxide levels returned to baseline values after discontinuation of viloxazine. In a seventh patient, viloxazine had to be discontinued after only two weeks because of severe side effects associated with a striking elevation of carbamazepine and carbamazepine 10,11-epoxide levels (by 197% and 137% respectively). Although viloxazine appears to be one of the few antidepressants which can be used safely in patients with epilepsy these results indicate that the drug should be prescribed with great caution in subjects treated with carbamazepine. The mechanism of the interaction probably involves inhibition of the metabolism of both carbamazepine and its active epoxide metabolite.

Sodium valproate and valpromide: differential interactions with carbamazepine in epileptic patients

To evaluate the comparative effects of valproic acid (VPA) and valpromide (VPM) on plasma levels and protein binding of carbamazepine (CBZ) and CBZ-10,11-epoxide (CBZ-E), 12 adult epileptic patients stabilized on CBZ monotherapy were divided into two groups. One group (n = 6) received sodium valproate (1,100 mg/day) for 2 weeks, while the other group (n = 6) was given, for the same period, a dosage of VPM (1,200 mg/day) expected to produce VPA levels equivalent to those achieved with valproate. Plasma CBZ levels were not affected by either treatment. In the valproate-treated group, plasma CBZ-E levels increased by 101% (range, 29-238%) within 1 week of combined therapy (p less than 0.02) and returned to baseline values after VPA treatment was stopped. In the VPM-treated patients, the elevation of plasma CBZ-E levels was much greater. In this group, plasma CBZ-E increased by 330% (range, 110-864%), and this was associated in two patients with the appearance of adverse effects which subsided after reducing the VPM dosage. The plasma protein binding of CBZ and CBZ-E was not affected significantly by VPM or valproate therapy. Plasma VPA levels were similar in the two groups. It is concluded that VPM is not simply a prodrug of VPA. Although both VPA and VPM increase CBZ-E levels--probably by inhibiting the enzyme epoxide hydrolase--the interaction caused by VPM is of much greater magnitude and potential clinical significance.

Pharmacokinetics of the antidepressant drug viloxazine in normal subjects and in epileptic patients receiving chronic anticonvulsant treatment

In order to evaluate the influence of chronic antiepileptic drug treatment on the kinetics of the antidepressant viloxazine (VLX), six drug-free control subjects and six epileptic patients treated with one or two anticonvulsants (phenobarbital, carbamazepine or phenytoin) were given a single oral dose of VLX (200 mg). On a separate occasion, the patients were also given 200 mg VLX by IV infusion. Plasma VLX levels were determined by GLC. Following oral dosing, VLX was rapidly absorbed from the gastrointestinal tract (peak levels at 0.5-4 h); plasma level profiles showed a considerable interindividual variability but did not differ significantly between patients and controls. Terminal half-lives were 4.3 +/- 1.5 h in the patients and 4.3 +/- 1.8 h in the controls. Clearance and volume of distribution calculated after IV dosing in the patients were 124 +/- 11 ml h-1 kg-1 and 0.73 +/- 0.28 l/kg, respectively. The absolute oral availability was 85 +/- 14%. At variance with findings reported for other antidepressants, VLX kinetics do not appear to be significantly altered by concurrent treatment with enzyme-inducing antiepileptic drugs.

A sensitive gas chromatographic assay for the determination of serum viloxazine concentration using a nitrogen-phosphorus-selective detector

A gas-liquid chromatographic procedure for measuring the serum levels of the antidepressant viloxazine is described. The drug and the internal standard [imipramine (IMI)] are extracted from 1 ml serum. The method involves a three-step extraction, derivatization of viloxazine with acetic anhydride, and injection into a gas chromatograph equipped with a nitrogen-phosphorus-selective detector. The retention times for IMI and viloxazine were 4.7 and 6.1 min, respectively. The standard curves were linear over the 100- to 2,000-ng/ml range. The recovery averaged 64.5% and the lowest detection limit was 80 ng/ml. The within-run and day-to-day coefficients of variations were 11.9 and 12.5%, respectively, at 250 ng/ml, and 8.9 and 9.2%, respectively, at 1,500 ng/ml. The method is adequate both for single-dose pharmacokinetic studies and for monitoring serum viloxazine levels in chronically treated patients.

Effect of viloxazine on serum carbamazepine levels in epileptic patients

The present study describes the interaction between carbamazepine (CBZ) and viloxazine, a recently synthesized antidepressant agent. Seven epileptic patients on chronic anticonvulsant therapy showed a significant (p less than 0.005) increase in steady-state serum CBZ levels (from 8.1 +/- 2.5 SD to 12.1 +/- 2.5 SD micrograms/ml) when viloxazine (300 mg/day) was added to the therapy. The effect was associated with the appearance of mild CBZ intoxication. The symptoms of this intoxication (i.e., dizziness, ataxia, fatigue, drowsiness) disappeared rapidly, and serum CBZ levels decreased to the basal values, when viloxazine administration was stopped.

Single-dose kinetics of primidone in acute viral hepatitis

The pharmacokinetics of primidone (PRM) after oral administration of a single 500 mg dose was studied in 7 patients with acute viral hepatitis and 7 healthy control subjects. The elimination half-life and the apparent clearance of unchanged PRM in the patients were 18.0 +/- 3.1 h and 42 +/- 14 ml X h-1 X kg-1, respectively (mean +/- SD) and did not differ significantly from the values in the controls (half-life 17.0 +/- 2.4 h; clearance 35 +/- 8 ml X h-1 X kg-1). The metabolite phenylethylmalonamide (PEMA) was detected in the serum of all normal subjects within 2-24 h. By contrast, serum levels of this metabolite were undetectable (less than 2 mumol/1) in all but one of the patients. Serum levels of phenobarbital (PB) remained below the limit of detection (less than 2 mumol/1) in all subjects. The findings indicate that accumulation of PRM with its attendant toxicity is unlikely to occur in epileptic patients who develop acute viral hepatitis, despite evidence that the metabolism of the drug is affected by this condition. The possibility of impaired conversion to PB and its implications are discussed.

Valproic acid-ethosuximide interaction: a pharmacokinetic study

The present pharmacokinetic study was designed to investigate the possible interaction between valproic acid (VPA) and ethosuximide (ESM) in humans. Six drug-free healthy volunteers, four men and two women, 18-42 years of age, received a single oral dose of 500 mg ESM before and during a treatment with VPA at 800- to 1,600-mg daily doses. The second ESM dose was given 9 days after VPA administration was started. In this latter condition, a significant (p less than 0.05) increase in ESM serum half-life, from 44 to 54 h on average, and a significant (p less than 0.05) decrease in total body clearance, from 11.2 to 9.5 ml/min on average, were observed. Other pharmacokinetic parameters were unchanged and showed values similar to those reported in the literature. Serum VPA levels ranged between 66.8 and 95 micrograms/ml. Two subjects showed no evidence of interaction. Although a great interindividual variability in the occurrence of VPA-ESM interaction can be observed, the present study indicates that VPA is able to inhibit the metabolism of ESM. Possible factors affecting this interaction are hypothesized and discussed.

Intra-daily oscillations in dipropylacetic acid plasma levels with two or three daily doses of dipropylacetamide in epileptic patients

The diurnal fluctuations in dipropylacetic acid (DPA) plasma levels were examined in ten epileptic patients following a chronic treatment with 3 or 2 daily doses of dipropylacetamide (DPM). The highest/lowest DPA levels ratios observed throughout 24 hrs were 1.18 and 1.36, respectively, but the difference in the data was not statistically significant (p greater than 0.05). The present results indicate that a reduction of the frequency of the daily administrations of the drug can be made with consequent possible improvement in the patient's compliance. The clinical value of the oscillations in DPA serum levels is also revised in the light of the data reported in the literature.

Increased dipropylacetic acid bioavailability from dipropylacetamide by food

The present study was designed to investigate the influence of food on dipropylacetic acid (DPA) absorption from dipropylacetamide (DPM). Six healthy male volunteers received at weekly intervals, in a crossover randomized fashion, a single oral dose of 60 mg DPM, as 2 X 300-mg capsules, in a fasting state and after a standard meal. In the latter state, the lag time of DPA appearance in the serum increased significantly (p less than 0.02) from 0.6 +/- 0.2 to 2.3 +/- 1.2 h (mean values +/- SD). Maximal DPA serum levels and bioavailability increased significantly (p less than 0.05), with mean values of 27.7 +/- 19.8 and 19.0 +/- 14.7%, respectively, following food. The slower gastric emptying with a consequent improved DPM exposure to metabolizing enzymes and changes in gastric pH probably accounted for these findings. These results suggest that it is more advantageous to take DPM after meals. This helps to reduce gastrointestinal disturbances and to promote DPA absorption.

Dipropylacetic acid plasma levels; diurnal fluctuations during chronic treatment with dipropylacetamide

Diurnal variation in dipropylacetic acid (DPA) plasma levels was investigated in 47 and 42 epileptic patients, chronically treated with sodium dipropylacetate and dipropylacetamide (DPM), respectively, taken alone or in addition to other antiepilepic drugs. Fluctuation in DPA plasma levels was significantly less in patients receiving dipropylacetamide. The slow absorption and the more prolonged plasma half-life of dipropylacetamide accounted for these findings. Although the importance of diurnal fluctuations in DPA levels has not yet been established, possible clinical implications are discussed.

Preliminary data on dipropylacetamide absorption in rats

Absorption of dipropylacetamide, after oral and i.m. administration, was studied in different groups of male albino Wistar rats. After i.m. administration, only unmodified amide was found in plasma, whereas oral administration of the drug was followed by the presence of dipropylacetic acid and dipropylacetamide in plasma. This last compound resulted in a higher amount in a further group of rats previously treated with neomycin in order to avoid the action of intestinal flora. Present results seem to exclude an hepatic role in the transformation of dipropylacetamide in dipropylacetic acid.