The effect of ethanol intake on propoxyphene absorption and biotransformation in dogs

The effect of ethanol (0.5 and 1.0 g/kg) on gastrointestinal absorption and presystemic biotransformation of propoxyphene (4 mg/kg) was studied in dogs in a crossover design. Low ethanol doses (0.5 g/kg) had no effect on the bioavailability of propoxyphene. High ethanol doses (1.0 g/kg) enhanced the bioavailability of orally administered propoxyphene significantly (p less than 0.05). With this dose of ethanol, the area under the blood concentration versus time curve (AUC)0-5 h of propoxyphene was approximately 200% of the control value. The level of norpropoxyphene, a major metabolite of propoxyphene, was significantly decreased (p less than 0.05) after administration of high ethanol doses. In all blood samples, after propoxyphene administration, an unidentified metabolite of propoxyphene was found, which formation was dose dependently inhibited by ethanol.

Severe acute propoxyphene overdose: plasma concentrations of propoxyphene and norpropoxyphene and the effect of dopamine on circulatory failure

Twelve patients with cardiovascular failure because of propoxyphene self-poisoning were treated with dopamine. The patients responded favourably to dopamine infusion (2-17 micrograms/kg/min) with a dose-dependent rise in systolic arterial blood pressure and a fall in central venous pressure and copious urinary output. Side effects during infusion were few, and in periods where dopamine infusion exceeded 10 micrograms/kg/min no tachyarrhythmias were seen. Eleven of the patients were treated on a respirator. Two patients were discharged from the ICU with signs of hypoxic brain damage, one of whom recovered completely after 2 weeks. Serum propoxyphene and norpropoxyphene were measured in nine patients. All but one patient had either propoxyphene or norpropoxyphene concentrations above 3 mumol/l.

Toxicological studies in a Distalgesic addict

The disposition and kinetics of paracetamol, dextropropoxyphene and their metabolites were investigated in an addict who claimed to be taking 80-100 Distalgesic tablets daily regularly. Plasma concentrations of paracetamol, dextropropoxyphene and their principal metabolites were measured after an oral dose of 15 Distalgesic tablets. The absorption of paracetamol and dextropropoxyphene was rapid with peak plasma concentrations at 15 and 30 min respectively. The elimination half-life for paracetamol was 2.3 h. Nordextropropoxyphene remained at steady state with very high plasma concentrations (5 mg/l). The urinary excretion of paracetamol and metabolites was not abnormal. The total recovery of paracetamol was only 31% of the dose. Apart from raised plasma gamma-glutamyltransferase activity there was no biochemical evidence for paracetamol-induced hepatocellular damage despite ingestion of 97.5 g of paracetamol over the 11 days of the withdrawal period.

The effects of dopamine on central hemodynamics and myocardial metabolism in experimental propoxyphene-induced shock

The hemodynamic and cardiometabolic effects of dopamine were evaluated in propoxyphene-induced circulatory shock in eight pentobarbital anesthetized pigs. Circulatory shock was induced by an infusion of propoxyphene chloride 15 mg . min-1 i.v. At shock, i.e. CI less than or equal to 2.0 l . min-1 . m-2 and/or MAP less than or equal to 60 mmHg, dopamine was infused at 10, 20, 40, 80 and 160 micrograms . kg-1 . min-1 with an interval between increments of 8 min. After 30 min at 160 micrograms . kg-1 . min-1, the infusion rate was reversibly decreased. The propoxyphene infusion of 15 mg . min-1 was continued throughout the study. Dopamine improved the circulation in seven animals; one animal died in refractory shock during dopamine infusion. Dopamine infusion at shock level resulted in an increase of the following variables (% of baseline value): MAP (69%), HR (109%), CI (138%) and SVI (129%). Normalisation was seen in MRAP (120%) and in MPAOP (100%). A profound decrease in systemic vascular resistance was unchanged. Increases were seen in left and right ventricular stroke work index, to 88% and 176% of baseline, respectively. Left ventricular dP/dt increased (170%). In the coronary circulation myocardial blood flow increased (133%) as did myocardial oxygen consumption (65%) concomitant with a decrease in myocardial oxygen uptake (41%), but coronary vascular resistance progressively decreased (38%). The myocardial propoxyphene extraction changed from +54% to -86% during peak dopamine infusion. In conclusion, dopamine reversed cardiac failure in propoxyphene overdose by a marked positive inotropic stimulation restoring contractility. A marked positive chronotropic stimulation maintained a sufficient cardiac index and a normal blood pressure in spite of a profound vasodilatation which was unresponsive to dopamine.

Liquid chromatographic determination of propoxyphene and norpropoxyphene in plasma and breast milk

A sensitive and specific high-performance liquid chromatographic (HPLC) procedure was developed for determination of propoxyphene and norpropoxyphene in plasma and breast milk. The compounds were isolated from the biological specimen by extraction, the organic phase was evaporated to dryness, and the residue was redissolved in mobile phase [acetonitrile: 0.002 M H2SO4 (1:1)]. The resultant solution was then injected into an HPLC system utilizing a C18 reversed-phase analytical column and a variable-wavelength detector set at 205 nm. Under these conditions the method has a sensitivity of 20 ng/mL using 1 mL of plasma or milk. The within-run coefficient of variation for both compounds varied between 6.2 and 8.9% within the concentration range tested. Applicability of the method was demonstrated in a nursing mother who received multiple oral doses of propoxyphene.

A high propoxyphene concentration

Approximately 10% of reported fatal poisonings with propoxyphene have blood concentrations exceeding 10 mg/L. A few have concentrations exceeding 100 mg/L. It is evident, therefore, that the blood does not reach propoxyphene "saturation" at either concentration. The ratios of propoxyphene to norpropoxyphene do not appear to differ markedly between drug abuse deaths and nonabuse deaths.

Deaths from paracetamol and dextropropoxyphene (Distalgesic) poisoning in England and Wales in 1979

Paracetamol and dextropropoxyphene were implicated on clinical and analytical grounds in 237 poison deaths in England and Wales in 1979. In addition to paracetamol, dextropropoxyphene and ethanol, other agents were detected in 61 of these cases (26%). Analytical evidence suggests that very substantial overdoses of paracetamol and dextropropoxyphene were ingested in the majority of cases; their mean plasma concentrations in those ingesting no other agents were 252 and 8.64 mg/l respectively. Significant quantities of ethanol were ingested in 133 of 237 cases (56%). The mean ethanol concentration in those in whom quantitative estimations of paracetamol, dextropropoxyphene and ethanol were undertaken and who had not ingested other drugs, was 1588 mg/l. There was no analytical support for the diagnosis of paracetamol and dextropropoxyphene poisoning in 74 of 305 cases (24%) of H.M. Coroners' returns to the Office of Population, Censuses and Surveys for the period 1 January-31 December 1979. In addition, dextropropoxyphene was detected analytically in six cases classified as being due to paracetamol alone.

Fatal self-poisoning in the UK and the paracetamol/dextropropoxyphene combination

Coroners' files have been examined to ascertain the numbers of deaths involving self-poisoning with analgesic drugs with specific reference to the paracetamol/dextropropoxyphene combination. The period of study was 1976-1980. This report concentrates on cases in England, although reference is made to similar deaths occurring in Scotland and Northern Ireland. Data have been collected extensively on a wide range of issues concerning fatal self-poisonings mainly by visiting coroners' offices in England to make direct investigation of records. The total number of cases where the paracetamol/dextropropoxyphene combination can be considered as ingested in the self-poisoning episode is underestimated. The number of cases involving alcohol and/or other drugs taken together with the combination product is particularly underestimated. Involvement of people aged 30 years and below comprises 32% of all cases. 'Gesture' overdoses comprise an estimated 14% of all cases in England. An analysis of fatalities from cases where quantities in post-mortem blood of dextropropoxyphene less than 1 microgram/ml and paracetamol less than 50 micrograms/ml are found and of cases where death occurs within 2 h of ingestion of the overdose has been carried out. The results are inconclusive. In most cases alcohol and/or other drugs are found to be involved. Critical inspection of coroners' files shows relatively few of these cases where the combination product is ingested on its own. There is wide variability in the data available in coroners' files. In many cases data of value to this research are not recorded. Medical history and quantitative levels of drugs suspected (particularly dextropropoxyphene) are particular examples of factors which may not be recorded. Office of Population, Censuses and Surveys (OPCS) mortality data are based on certified causes of death. Because of the underestimate of the involvement of this combination product and the under-reporting of other drug and/or alcohol ingestion with the combination, care must be exercised in quoting or drawing conclusions from OPCS statistics.

Capillary and packed column GC determination of propoxyphene and norpropoxyphene in biological specimens: analytical problems and improvements

Several problems associated with the gas chromatographic determination of DPX and NDPX are discussed and an improved method for their extraction and quantification is described. The method involves two separate extractions, one for DPX with SKF 525A as the internal standard and one for NPDX with dinor-LAAM as the internal standard. The use of two internal standards improved quantitative reproducibility by almost 50%. It was also found that routine DPX and NDPX assays were better determined on packed columns than on capillary columns because the quality of the samples and of the columns was critical. The use of two IS and the double extraction procedure is recommended for general toxicological analyses.

Propoxyphene in postmortem toxicology 1976-1978

A total of 1859 cases provides the basis for this study in which propoxyphene, and often its major metabolite, was demonstrated by toxicological analysis in the blood or tissues of the deceased at 27 medical examiner or coroner's offices across the United States and Canada. The study period includes the last five months of 1975 through December 1978. The cases describe a clearly defined adult population with a marked tendency toward hypochondria, chronic minor illness, and severe psychiatric problems. The high proportion of suicides (44.1% of the total cases and 54.0% of the drug-caused deaths) and multiple-drug toxicities (88.6%) suggests that the involvement of propoxyphene in many of these fatalities may be of less significance than the phenomenon of "polypharmacy" and self-medication without appropriate medical supervision. This evaluation of propoxyphene provides no evidence that propoxyphene is responsible for "street-drug" fatalities. Its appearance in postmortem toxicological examinations has been declining sharply since 1977, but it continues to be dangerous when used excessively, particularly in combination with alcohol and other central nervous system depressant drugs.

Propoxyphene and norpropoxyphene plasma concentrations after oral propoxyphene in cirrhotic patients with and without surgically constructed portacaval shunt

Plasma concentrations of propoxyphene and its major metabolite, norpropoxyphene, were determined over at least 12 hr after oral administration of 130 mg dextropropoxyphene hydrochloride to eight men with hepatic cirrhosis, of whom four had a surgically constructed portacaval shunt, and to seven healthy men. Propoxphene concentrations were appreciably higher and norpropoxyphene concentrations were much lower in the patients than in the normal subjects. The ratio of areas under the plasma concentration-time curve from 0 to 12 hr, norpropoxyphene: propoxyphene, was 0.70 +/- 0.46 (x +/SD) in patients and 3.94 +/ 0.83 in normal subjects. A similar decrease in this ratio was observed previously in otherwise healthy dogs after surgical construction of portacaval shunt when propoxyphene was given orally, but not after intravenous injection of the drug. A woman with portacaval shunt and essentially complete renal failure was also studied; she exhibited the highest propoxyphene peak concentration in this investigation and had no detectable norpropoxyphene in plasma. Most of the patients, unlike the normal subjects, experienced considerable sedation after propoxyphene. These results are probably due to increase systemic availability of orally administered propoxyphene in patients with hepatic cirrhosis and possibly to increased receptor response to the drug by these patients. It is concluded that propoxyphene should be administered cautiously and in reduced doses to patients with hepatic dysfunction.

Deaths related to propoxyphene overdose: a ten-year assessment

Of 81 fatal overdoses of propoxyphene identified over a ten-year period, suicide accounted for 76.5% and accidents for 23.5%. The incidence sharply increased in 1973 and the death rate has remained constant since then. In two thirds of the suicidal overdose deaths, additional drugs were encountered. Alcohol was detected in an additional 15%, and propoxyphene preparations alone were used in 19%. In the 19 deaths from accidental overdose, six resulted from recreational abuse, and additional drugs were detected in all. Five who dief of propoxyphene preparations alone had significant medical illnesses. Eight nonrecreational users died after taking other drugs or alcohol along with propoxyphene. Only one individual in the entire series was found to be dependent on propoxyphene. Although propoxyphene cannot be regarded as a harmless drug, the study indicates a very low rate of dependency and a low potential for recreational abuse. As with other drugs, adequate warnings concerning dosage abuse and the concurrent use of alcohol and other drugs must be stressed. The suggestion to reclassify propoxyphene to a Schedule II drug does not appear justified.

Propoxyphene and norpropoxyphene plasma concentrations in the anephric patient

The widely used analgesic propoxyphene is subject to extensive presystemic (first-pass) biotransformation after oral administration. There have been indications that presystemic biotransformation of a drug may be less in anephric patients than in healthy subjects. Plasma concentrations of propoxyphene (a drug with dangerous adverse effects at high concentrations) and its major and pharmacologically active metabolite norpropoxyphene have been compared in 7 anephric patients and 7 healthy subjects after oral administration of a 130-mg dose. Maximum propoxyphene concentrations were much higher (177 +/- 16 vs 81 +/- 35 ng/ml, mean +/- SD, p less than 0.001), and areas under the concentration-time curve over 12 hr were much larger (4,310 +/- 1,520 vs 2,250 +/- 1,050 ng hr/ml, p less than 0.02) in the anephric patients than in the normal subjects. These differences were statistically significant even after normalization for dose per body weight. Norpropoxyphene concentrations were also higher and more persistent in the anephric patients. These differences, which appear to result from decreased presystemic biotransformation of propoxyphene and decreased elimintation of norpropoxyphene, indicate that propoxyphene should be used cautiously and at reduced doses in patients with renal failure.

Effect of hemodialysis on propoxyphene and norpropoxyphene concentrations in blood of anephric patients

Our purpose was to determine whole-blood hemodialysis clearances and the effect of hemodialysis on blood propoxyphene concentrations and of its major metabolite, norpropoxyphene, in anephric patients under apparent steady-state conditions with respect to propoxyphene. Propoxyphene hydrochloride 130 mg was given orally every 8 hr for 7 doses to 4 patients. Blood propoxyphene and norpropoxyphene levels were determined repeatedly during the sixth dosing interval (before hemodialysis) and during the seventh dosing interval (during hemodialysis). There were no statistically significant differences in the areas under the blood level/time curves of propoxyphene and norporopoxyphene during the sixth and seventh dosing intervals, indicating that hemodialysis contributes negligible to their total clearance from the body. The low hemodialysis clearances of propoxyphene and norpropoxyphene were confirmed by direct in vivo determination of their hemodialyzer extraction ratios. Propoxyphene produces much higher propoxyphene plasma levels and higher as well as more persistent norpropoxyphene plasma levels in anephric patients than in normal subjects. In view of their substantive cumulation during repeated propoxyphene administration, their central nervous system and cardiac toxicity at high concentrations, their low hemodialysis clearance, and the apparent sensitivity of patients with renal failure to narcotics, propoxyphene should be used cautiously in anephric patients.

Cardiopulmonary, behavioral, and pharmacokinetic effects of propoxyphene in horses

The acute behavioral cardiopulmonary and pharmacokinetic effects of propoxyphene hydrochloride were studied in seven adult horses. Each horse was given three different dosages of propoxyphene (0.5, 1.0, 2.2 mg/kg) IV. Fourteen days was allotted between each drug administration. The lower IV dosages of propoxyphene (0.5, 1.0 mg/kg) resulted in no changes in indices of cardiopulmonary function. Four horses demonstrated a transient period of muscle fasciculations when given 0.5 mg of propoxyphene/kg. Horses given 1.0 mg/kg demonstrated a brief period of euphoria, ataxia, and muscle fasciculations followed by a period of increased motor activity lasting for approximately 30 minutes. Horses given 2.2 mg of propoxyphene/kg demonstrated significant (P less than 0.05) increases in heart rate and arterial blood pressure and, after a brief period of ataxia and disorientation, displayed increased motor and locomotor activity lasting several hours. These behavioral effects were less apparent in three of four horses 4 hours after their appearance by the IV administration of naloxone. Propoxyphene exhibited a dose dependent half-life of from 61 to 135 minutes and an apparent volume of distribution of from 2.54 to 4.26 L/kg. Total body clearance was 21.9-28.4 ml/min/kg. In the adult pain-free horse, propoxyphene causes dose dependent excitatory effects similar to the narcotic analgesics.

d-Propoxyphene kinetics after single oral and intravenous doses in man

d-Propoxyphene kinetics was studied in 8 healthy male subjects after single oral doses of d-propoxyphene at 65, 130, and 190 mg and after slow intravenous infusion of 65 mg. Total urinary excretion (7 days) indicated complete oral absorption but systemic availability was reduced corresponding to fist-pass elimination of 30% to 70%. There was linearity between oral dose and the corresponding area under the plasma concentration/time curve of d-propoxyphene and the metabolite norpropoxyphene. The kinetic measurements showed 2- to 3-fold interindividual variations: oral clearance, 1.3 to 3.6 1/min; systemic clearance, 0.6 to 1.2 1/min; apparent volume of distribution, 700 to 1,800 1; d-propoxyphene half-life (t1/2), 8 to 24 hr; and norpropoxyphene t1/2, 18 to 29 hr. There were pronounced intraindividual dose-dependent variations in oral clearance in some subjects. The intravenous concentration curves indicated a 3-compartment distribution model.

Cardio-respiratory toxicity of propoxyphene and norpropoxyphene in conscious rabbits

The toxic effects of alpha-d-propoxyphene (P) and its primary metabolite alpha-d-norpropoxyphene (NP) were compared to intravenous infusions (100 min.) of equimolar doses of P and NP (80 micronmol/kg equivalent to 30 mg/kg P HCl) in conscious rabbits. During P infusion severe respiratory depression and convulsions were seen in all animals, and six of the nine animals died. During NP infusion, however, only minimal respiratory depression was seen and all the animals survived. Considerable prolongation of the QRS complex and cardiac arrhythmias like intermittent A-V block and ventricular extrasystoles were seen in the ECG during both P and NP infusion, while the arterial blood pressure was unchanged. In P injection experiments (6 mg/kg P HCl), ECG changes preceded reduction in respiratory rate and during NP infusion only minor changes were seen in arterial blood gases, demonstrating that the ECG changes produced by P and NP are independent of respiratory depression. The ECG changes were found to be similar to those reported in quinidine intoxication. The QRS prolongation was markedly correlated with plasma concentrations during and after P and NP infusion. The results of the present investigation favour the hypothesis that the contribution of NP to the toxicity of oral P overdosage in man is ascribed to its cardiotoxic action whereas P is responsible for the CNS toxicity (respiratory depression and convulsions) as well as cardiotoxicity.

Plasma protein binding of d-propoxyphene in normal subjects and anephric patients

The free fraction of d-propoxyphene in the plasma of normal subjects is 0.24 +/- 0.02 (mean +/- S.D.) and is not concentration dependent in the usual therapeutic and toxic conentration range. Renal failure and relatively high concentrations of d-norpropoxyphene, the major metabolite of d-propoxyphene, have no significant effect on the plasma protein binding of d-propoxyphene.

Pharmacokinetics of dextropropoxyphene in acute poisoning

Dextropropoxyphene (DP) is a commonly used medicament for suicide attempts in Denmark. Death may occur from respiratory depression or cardiac arrest. Mechanical hyperventilation which induces hypocapnia seems to reduce the occurrence of cardiac complications. In an attempt to relate the clinical events to the plasma concentrations of DP and the major metabolite norpropoxyphene (NP) we studied patients with acute poisoning treated either for 48 h with induced hypocapnia by hyperventilation or under a conservative regime. Hypocapnia was found to lead to a significant increase in the plasma half-life of DP. Under conservative treatment the plasma half-life was 17.9 +/- 6.7 (S.D.) h (n = 6), while under induced hypocapnia the mean of values from 5 patients was 30.5 +/- 6.9 (S.D.) h. Maximum serum levels of DP and NP were, however, significantly higher in the intensively treated patients (n = 7) than in those treated conservatively (n = 9), though less marked for NP compared to DP (DP: 4.9 +/- 2.1/2.4 +/- 1.0 mumol/l, NP: 6.3 +/- 2.4/4.1 +/- 1.7 mumol/l). A concentration dependent renal clearance of NP was not demonstrable. Possible explanations are the following: 1) A change in disposition pattern blood/tissue of DP during hypocapnia. 2) A reduced metabolism DP to NP during hypocapnia. 3) A reduction in other routes of elimination.