The novel drug zimelidine 50-300 mg/day was administered to 12 depressed patients. After about 3 weeks plasma levels of the demethyl metabolite, norzimelidine, were almost thrice those of the parent drug. ...
Several metabolites of (Z)-3-(4-bromophenyl)-N,N-dimethyl-3-(3-pyridyl)allylamine (zimelidine) were isolated from urine of rat and dog after administration of the 14C-labelled drug. The major metabolic routes found in these species involve oxidations at both the aliphatic and aromatic nitrogen, N-demethylations and deamination of the aliphatic nitrogen. The major excretion products in urine from both rat and dog were the N-oxide of zimelidine, the deamination product 3-(4-bromophenyl)-3-(3-pyridyl)-acrylic acid and its N-oxide. Apparently, there are only minor differences between rat and dog in the metabolism of zimelidine. The N-oxide of zimelidine and the acrylic acid derivative were also identified in a human urine sample. Zimelidine was labelled with 14C in the allylic position. Most of the metabolites were synthesized in pure diastereomeric form and their configuration were shown by UV and 1H-NMR.
The acute interaction of zimelidine (Z) with ethanol (E) was examined in six healthy men aged 20 to 37 yr who randomly received each of four treatments 1 wk apart: Z, 200 mg by mouth, preceded by 1 hr and followed for 7 hr of oral E in juice dosed to maintain blood alcohol concentrations between 800 and 1000 mg/L; placebo Z and E; Z and juice; and placebo Z and juice. E decreased the rate of biotransformation of Z to norzimelidine (NZ) by 46%, but the AUCs of Z, NZ, and their total concentration over 8 hr were not altered by E. Acetaldehyde concentrations did not change and no aversive alcohol-sensitizing reaction was detected. E-induced impairments in memory, body sway, and a manual tracking task were further enhanced by Z, as was the E-induced decrease in friendliness. Data suggest Z and E interact kinetically and dynamically and suggest a mechanism whereby Z may decrease E intake in man.
/SRP:/ Immediate first aid: Ensure that adequate decontamination has been carried out. If patient is not breathing, start artificial respiration, preferably with a demand valve resuscitator, bag-valve-mask device, or pocket mask, as trained. Perform CPR if necessary. Immediately flush contaminated eyes with gently flowing water. Do not induce vomiting. If vomiting occurs, lean patient forward or place on the left side (head-down position, if possible) to maintain an open airway and prevent aspiration. Keep patient quiet and maintain normal body temperature. Obtain medical attention. /Poisons A and B/
/SRP:/ Basic treatment: Establish a patent airway (oropharyngeal or nasopharyngeal airway, if needed). Suction if necessary. Watch for signs of respiratory insufficiency and assist ventilations if needed. Administer oxygen by nonrebreather mask at 10 to 15 L/min. Monitor for pulmonary edema and treat if necessary ... . Monitor for shock and treat if necessary ... . Anticipate seizures and treat if necessary ... . For eye contamination, flush eyes immediately with water. Irrigate each eye continuously with 0.9% saline (NS) during transport ... . Do not use emetics. For ingestion, rinse mouth and administer 5 mL/kg up to 200 mL of water for dilution if the patient can swallow, has a strong gag reflex, and does not drool ... . Cover skin burns with dry sterile dressings after decontamination ... . /Poisons A and B/
/SRP:/ Advanced treatment: Consider orotracheal or nasotracheal intubation for airway control in the patient who is unconscious, has severe pulmonary edema, or is in severe respiratory distress. Positive-pressure ventilation techniques with a bag valve mask device may be beneficial. Consider drug therapy for pulmonary edema ... . Consider administering a beta agonist such as albuterol for severe bronchospasm ... . Monitor cardiac rhythm and treat arrhythmias as necessary ... . Start IV administration of D5W /SRP: "To keep open", minimal flow rate/. Use 0.9% saline (NS) or lactated Ringer's if signs of hypovolemia are present. For hypotension with signs of hypovolemia, administer fluid cautiously. Watch for signs of fluid overload ... . Treat seizures with diazepam or lorazepam ... . Use proparacaine hydrochloride to assist eye irrigation ... . /Poisons A and B/
/CASE REPORTS/ The side effects of an overdose in a 29-yr-old patient who had taken zimeldine, 5.2 g, were reported. The plasma concentration of zimeldine at 8 hr after admission was 11544 nmol/L, and that of nomelidine was 4233 nmol/L. After 6 days, the blood level of zimeldine was 0, and that of nomelidine was 675 nmol/L. Cardiovascular changes consisted only of tachycardia and prolongation of the PR interval, which resolved within 8 hr. Abdominal symptoms consisted of nausea and tenderness which persisted for 3 days. Effects on the nervous system included pupillary dilation, horizontal nystagmus, tremor, hypertonia and hyperreflexia, all of which resolved with 24 hr.
The pharmacokinetics of zimeldine, a 5-HT reuptake blocker with antidepressive effects, was studied after a single oral dose and after multiple oral administration in 19 alcoholic males, 10 with and 9 without chronic liver damage. The average plasma concentration of zimeldine as assessed by the AUC values (area under the plasma concentration-time curve) was significantly higher in the chronically liver damaged patients than in the patients without chronic liver damage. The plasma half-life of zimeldine was also significantly longer in the chronically liver damaged patients. There were no differences in the obtained pharmacokinetic parameters between the patients having nonchronic liver damage and healthy control subjects. The pharmacokinetics of the active metabolite norzimeldine (resulting from N-demethylation of zimeldine) showed no differences between the two groups of alcoholics and the healthy controls. The IgA values were significantly correlated to both the AUC and plasma half-life of zimeldine. No other correlation between clinical chemistry parameters and pharmacokinetic parameters of zimeldine and norzimeldine were found.
Five healthy adults were administered zimelidine orally (150 mg) and by intravenous infusion (20 mg) in a crossover design. Blood and urine samples were collected for a period of 28 hours after dosing and the concentrations of zimelidine and norzimelidine determined. There was no significant difference in terminal phase half-life of zimelidine after oral (4.7 hr +/- 1.3 SD) or intravenous dosing (5.1 hr +/- 0.7 SD). An average of 50% of the ingested oral dose reached the systemic circulation. Excretion of unchanged zimelidine in urine was on average 1.26% of the intravenous dose. It appears that zimelidine is completely absorbed from the gastrointestinal tract and "first-pass metabolism" in the liver reduces the bioavailability to 50%. The mean plasma half-life for norzimelidine was 22.8 hr. The area under the plasma concentration time curve for norzimelidine after oral administration was 92% of that after intravenous administration. The plasma concentration of both zimelidine and norzimelidine are predicted to approach steady-state within 3-5 days.
The kinetics of zimeldine (Z) and its demethylated metabolite, norzimelidine (NZ), were determined after administration of a single 200 mg oral dose of Z to 6 healthy volunteers (Group I), and to patients with mild (Group II) and severe renal failure (Group III). Z and NZ concentrations were assayed by HPLC in serial plasma and urine samples over 6 days following the dose. In Group I Z was rapidly absorbed and metabolized into NZ, and then the plasma concentrations declined with apparent elimination half-lives of 8.4 h and 24.9 h for Z and NZ respectively, whilst the renal clearance of both compounds was low, Z 15.7 ml/min and NZ 33.0 ml/min. The plasma level of Z differed little between Groups I and III, but the area under the curve was significantly higher in Group III than in Group I subjects (AUC0-144 = 17.3 and 6.8 mumol X l-1 X h, respectively). Severe renal failure did not affect the peak plasma concentration of NZ but it did significantly increase peak time, apparent elimination half-life, and the area under the plasma concentration curve. A significant inverse relationship was found between renal clearance of NZ and plasma creatinine. Since NZ is as pharmacologically potent as Z, the results suggest that the dose of Z should be reduced in patients with severe renal insufficiency.
