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At least 19 recordsLinked to original sources

PubMed1979

Effects of tolmetin, paracetamol, and of two combinations of tolmetin and paracetamol as compared to placebo on experimentally induced pain. A double blind study.

Previous studies in animals suggested that a coadministration of the anti-rheumatic/anti-inflammatory agent tolmetin (Tolectin) and of paracetamol potentiates the effects of these two drugs. The present study was carried out to assess whether or not the dosis of tolmetin necessary to obtain an analgesic effect can be reduced when paracetamol is coadministered in a model with experimentally induced pain in healthy human subjects. The effects of tolmetin 200 mg (T 200), paracetamol 400 mg (P 400), tolmetin 150 mg plus paracetamol 300 mg (T 150 + P 300), and of tolmetin 100 mg plus paracetamol 400 mg (T 100 + P 400) on pain threshold to electrical and thermal stimuli and on pain tolerance to electrical stimuli were compared to the effects of placebo under double blind conditions. Each of 20 healthy volunteers received all of the 5 treatments randomised according to four 5 X 5 Latin squares. The results showed that the combination T 100 + P 400 had better analgesic effects than the double dose of tolmetin, T 200, alone, while the effects of P 400 could not be discrminated from placebo. In a sequential t-test the effects of T 100 + P 400 could be discriminated from placebo already after 14 Ss. The effects of T 200, T 150 + P 300, and T 100 + P 400 respectively could not be differentiated, indicating that the dose of tolmetin can be reduced markedly by simultaneous administration of paracetamol without a loss in analgesic potency. Coadministration of tolmetin and paracetamol permits a marked reduction of the dose of tolmetin without any loss of analgesic potency as measured in a model with experimentally induced pain in healthy subjects.

Acetaminophen↗

PubMed1977

A double-blind comparative evaluation of aspirin, paracetamol and paracetamol + caffeine (finimal) for their analgesic effectiveness.

A double-blind, cross-over trial was made of three analgesic preparations--paracetamol, paracetamol with caffeine (Finimal) and aspirin in the relief of postoperative pain in 72 orthopedic inpatients and in 144 ambulatory outpatients suffering form common idiopathic headache. The combination of paracetamol and caffeine (Finimal) in this study shows the greatest pain relief in both groups of patients. This evaluation supports the results of BOOY3 demonstrating the superiority of the paracetamol-caffeine combination to paracetamol alone or aspirin.

Acetaminophen↗

PubMed1979

Effect of paracetamol on amylobarbitone hydroxylation in man: a gas chromatographic method for simultaneous estimation of underivatized paracetamol and barbiturates.

A rapid and specific technique for the simultaneous gas chromatographic estimation of underivatized paracetamol and barbiturates using an alkali flame ionization detector is described which is suitable for both forensic and pharmacokinetic investigations. An improved method for estimation of 3-hydroxyamylobarbitone is also detailed. These techniques were used in an investigation of the effects of oral administration of 1 g paracetamol 8 hourly on the formation of 3-hydroxyamylobarbitone from a single oral dose of 200 mg sodium amylobarbitone. No significant changes were found in the plasma concentrations and total body clearance of amylobarbitone nor was there any alteration in the urinary elimination of 3-hydroxyamylobarbitone.

Acetaminophen↗

PubMed1979

Paracetamol (acetaminophen) clearance in patients with cirrhosis of the liver.

The pharmacokinetics of paracetamol were studied in 11 patients with cirrhosis of the liver and 12 controls. The average biological half-life after oral administration of 1 g paracetamol was significantly prolonged in patients with hepatic cirrhosis compared to the controls (3.7 hr vs.2.1 hr) and, correspondingly, the average plasma clearance was significantly reduced from 337 ml x min-1 in the controls to 162 ml x min-1 in the patients with cirrhosis of the liver. After subchronic dosing of paracetamol with 1 g paracetamol t. i. d. the plasma half-lives of paracetamol remained unchanged. Steady-state levels of paracetamol were significantly increased in the patients with cirrhosis of the liver. A significant correlation between the values of plasma clearance of paracetamol and prothrombin time (r = +0.88), galactose elimination capacity (r = +0.66), plasma albumin (r = +0.85) was found. No clinical or biochemical signs of hepatotoxicity were observed during the study.

Acetaminophen↗

PubMed1979

The gastrointestinal absorption of paracetamol in the rat.

The absorption of [3H]paracetamol by rat small intestine, colon and stomach was studied in vivo and in vitro. Small intestinal in vivo studies, using a wide range of drug concentrations, showed that absorption was efficient and uniform throughout the small bowel, no site showing preferential absorption. Double reciprocal and direct plots indicated first order kinetics. The pattern was not observed when uptake was occurring from high concentrations of paracetamol in suspension. Gastric and colonic in vivo studies showed that there was appreciable absorption of [3H]paracetamol from these sites. In vitro studies using everted intestinal sacs showed no effect on paracetamol transfer when the incubation temperature was lowered to 10 degrees C or when iodoacetate (5 X 10(-2)M) and 2.4 dinitrophenol (5 X 10(-4)M) was added to the incubation medium. There was, however, a significant reduction in transfer of paracetamol against a concentration gradient of 10:1 applied across the mucosa. These data suggest that the uptake of paracetamol is by a passive transport process and confirm the efficiency of paracetamol absorption observed indirectly by others.

Acetaminophen↗

PubMed1979

Paracetamol versus placebo: effects on post-operative course.

Paracetamol was compared with placebo in a double-blind crossover study, in which essentially the same operation was performed on two separate occasions in 24 healthy patients, namely surgical removal of bilateral impacted wisdom teeth. Commencing on the day of surgery, either paracetamol (Panodil; 1.0 g x 4 for 2 days, then 0.5 g x 4 for the next 2 days) or placebo tablets were given, followed by crossover to the alternative treatment at the second operation about 4 weeks later. Several objective and subjective assessments were recorded for paired comparison of post-operative courses. Swelling on the 3rd day after operation when paracetamol was given averaged 71% of that measured when placebo was given (p less than 0.05). After paracetamol, a tendency was noted towards reduced local hyperpyrexia and less post-operative bleeding. The pain and preference scores were clearly in favour of paracetamol. The results provide evidence to suggest that paracetamol may reduce an acute, posttraumatic inflammatory reaction.

Acetaminophen↗

PubMed1976

A method for the estimation of acetanilide, paracetamol and phenacetin in plasma and urine using mass fragmentography.

Phenacetin, paracetamol and acetanilide can be determined in a plasma or urine sample by the use of deuterium labelled analogues. These are produced by reaction of hexadeuterioacetic anhydride with the appropriate aromatic amine. The -NHCOCD3 group is stable to hydrogen exchange below pH 8. The internal standard is added to the plasma or urine after enzymatic hydrolysis of the paracetamol conjugates and an ethyl acetate extract at pH 5 is evaporated under nitrogen and the residue derivatized with N,O-bis-(trimethylsilyl)-acetamide. An aliquot of this solution is injected into a g.c.m.s. system, and one ion characteristic of the material under study and the ion from the deuterium analogue (3 mass units greater) are monitored using a voltage switching technique. In the case of phenacetin, for example, ions at 251 and 254 are monitored. Calibration curves relating different weight ratios of the hydrogen and deuterium compounds to their respective signals from the gas chromatography mass spectrometer are used to calculate the amount of a compound in a particular sample. These methods have been developed to study the oxidation of acetanilide to paracetamol and the de-ethylation of phenacetin to paracetamol. Preliminary results from experiments with phenacetin will be discussed.

Acetaminophen↗

PubMed1975

Oral antipyretic therapy: evaluation of benorylate, an ester of acetylsalicylic acid and paracetamol.

The capacity of benorylate, an ester of acetylsalicylic acid and paracetamol, to reduce fever in children was compared with that of the components as such or as a combination. The series of cases studied consisted of 66 patients between the ages of 4 months and 12 years with rectal temperatures above 38.5 degrees C. Temperatures were recorded at 15 and 20 min and 1, 2, 4 and 6 hrs after the administration of the drug. The antipyretic effect of combined acetylsalicylic acid (11 mg/kg) and paracetamol (14 mg/kg) was superior to the effect of benorylate with a dose of 25 mg/kg and even of 50 mg/kg as well as better than the effect of either drug alone. Acetylsalicylic acid (10 mg/kg) and paracetamol (12.5 mg/kg) alone produced a significantly greater antipyretic effect than benorylate with a dose of 25 mg/kg. Given in a dose of 35--40 mg/kg, benorylate seems to have a significant antipyretic effect. However, this effect is clearly smaller than that of either of its components, acetylsalicylic acid or paracetamol. Therefore benorylate is probably not suitable to be used as a general antipyretic agent in children.

Acetaminophen↗

PubMed1975

Liver damage after paracetamol overdose. Comparison of liver-function tests, fasting serum bile acids, and liver histology.

54 patients have been studied after paracetamol (acetaminophen) overdose. Liver-function tests and fasting serum bile-acids were measured daily; liver biopsy was done in all cases, and slides were examined "blind" to assess liver damage. The plasma-paracetamol was measured on one occasion. A histological abnormality was present in the livers of 53 of the 54 patients, and was minor in 23, moderate in 16, and severe in 14. In 6 patients with moderate and 18 with mild histological abnormality liver-function tests were normal. A serum-aspartate-aminotransferase above 400 units/1 was always associated with severe histological liver damage. Fasting serum bile-acids were raised in 51 of the patients with abnormal liver histology; the serum-bile-acid seemed to be a more sensitive indicator of mild liver-cell damage than was the transaminase level. There was, however, little correlation between increase in bile-acid concentration and the degree of histological abnormality. As a result of these investigations empirically determined levels of plasma-paracetamol have been drawn which give a guide to the likelihood of liver damage after paracetamol overdose.

Acetaminophen↗

PubMed1977

Treatment of paracetamol (acetaminophen) poisoning with N-acetylcysteine.

Fifteen patients with paracetamol (acetaminophen) poisoning were treated with intravenous N-acetylcystein (300 mg/kg given over 20 h). Mean admission and 4 h plasma-paracetamol concentrations were 262 and 369 microgram/ml, respectively. Liver-function tests remained normal or were only slightly disturbed in 11 of 12 patients treated within 10 h of paracetamol ingestion. Severe liver damage developed in the other patient and in the three in whom treatment was started more than 10 h after paracetamol ingestion. In contrast to cysteamine, N-acetylcysteine was very well tolerated and has the advantage of being available as a pharmaceutical preparation in a 20% sterile solution.

Acetaminophen↗

PubMed1979

Effect of gel fibre on gastric emptying and absorption of glucose and paracetamol.

To determine the part played by altered gastric emptying in the modification of glucose absorption by gel fibres, glucose tolerance tests were done in seven healthy volunteers with and without the addition of pectin to the ingested glucose solution and after pharmacological inhibition of gastric emptying with propantheline. Compared with the controls, pectin significantly reduced blood-glucose. Propantheline had a similar but more pronounced effect. Pectin and guar gum did not substantially alter glucose tolerance in a patient who had had total gastrectomy. In a further investigation, gastric emptying and paracetamol absorption were studied simultaneously in fourteen subjects. In eight of these the study was repeated after addition of guar gum and pectin to the ingested paracetamol. Both gastric emptying and paracetamol absorption were slower after gel fibre but the total absorption of the drug, reflected in urinary recovery, was not significantly reduced. The results suggest that the effects of guar gum and pectin on glucose tolerance and paracetamol absorption could be due simply to alteration in the rate of gastric emptying.

Absorption↗

PubMed1979

Inappropriate methods for the emergency determination of plasma paracetamol.

Methods for the estimation of plasma paracetamol which depend on acid hydrolysis to p-aminophenol without a prior extraction step also measure inactive metabolites which are present in high concentrations. The extent of the overestimate obtained with such methods was determined using 24 samples from patents after paracetamol overdosage. There was a positive error of between 40 and 700% compared with a high-performance liquid chromatography reference method which measured only unchanged paracetamol. These non-specific methods should not be used to determine the need for specific therapy in patients with paracetamol poisoning.

Acetaminophen↗

PubMed1977

Comparative metabolism of benorylate and an equivalent mixture of aspirin and paracetamol in neonate and adult rabbits.

1. Benorylate was well absorbed in rabbits, but more slowly than an equimolar mixture of aspirin and paracetamol. 2. Benorylate was extensively hydrolysed and converted to the typical metabolites of aspirin and paracetamol by both neonate and mature rabbits. 3. Absorption of either aspirin-paracetamol or benorylate was slower in neonate rabbits than in adult rabbits. 4. The excretion rate in adult rabbits was faster, for both aspirin and paracetamol metabolites, than in neonate rabbits.

Acetaminophen↗

PubMed1977

Antipyretic therapy. Comparison of rectal and oral paracetamol.

The absorption of paracetamol from syrup, tablet and two different suppository bases was compared in six adult volunteers using urinary excretion measurements. The total amount of paracetamol and its metabolites excreted and the peak excretion rates were lower from the suppository bases than from the oral dosage forms. Absorption was a little better from a polyethylene glycol suppository base than from a triglyceride base. The antipyretic efficacy of a paracetamol syrup and suppository at a dose of 10 mg/kg was compared in 30 children between the age of 4 months and 12 years, who had infections and a rectal temperature above 38.5 degrees C. Both dosage forms produced a significant decrease in temperature, the greatest fall being about 2 hours earlier with the oral dosage form. The syrup also seemed to be significantly (p less than 0.05) more effective (maximum fall of temperature 1.58 degrees C) in reducing fever than the suppository, which produced its greatest fall of temperature (1.24 degrees C) six hours after insertion of the suppository. From the practical point of view both forms can be regarded as safe and effective antipyretics.

Acetaminophen↗

PubMed1976

Cysteamine, methionine, and penicillamine in the treatment of paracetamol poisoning.

60 patients with paracetamol poisoning have been treated with intravenous cysteamine, L-methionine, or D-penicillamine and the incidence and severity of hepatic necrosis compared with those observed in 70 patients receiving supportive therapy only. Of 31 patients with 4-hour plasma-paracetamol concentrations greater than 250 mug/ml given supportive therapy 22 sustained severe liver damage, 3 died in hepatic failure, and 4 developed acute renal failure. None of 23 similarly poisoned patients given cysteamine within 10 hours of ingestion suffered severe liver damage or renal failure and none died. Cysteamine was partially effective at 10-12 hours, but ineffective 12 hours or more after ingestion. Liver damage was absent or mild in 17 patients given L-methionine within 10-12 hours of ingestion but severe in 3 treated within 10 hours. Of 5 patients treated with D-penicillamine, 1 developed severe liver damage with acute renal failure. It is concluded that cysteamine prevents severe liver damage after paracetamol poisoning if given within 10 hours in adequate dosage.

Acetaminophen↗

PubMed1978

Chronic hepatic inflammation and fibrosis due to low doses of paracetamol.

Chronic hepatic necrosis developed in a man who had been taking 4 g of paracetamol daily for about a year (cumulative dose 1700 g). Liver biopsy done 23 days after the drug was stopped showed prominent diffuse central necrosis and portal changes. Repeat biopsy 5 months later showed chronic active hepatitis. This prompted anti-inflammatory treatment, with subsequent improvement in liver histology. Liver concentrations of reduced glutathione and paracetamol metabolism, assessed 1-1 1/2 years after drug was stopped, were normal; the basis for this patient's drug sensitivity is thus unclear. In some patients, chronic ingestion of therapeutic doses of paracetamol may produce hepatic necrosis and hepatitis which persist long after the drug has been discontinued.

Acetaminophen↗

PubMed1977

Some mechanisms involved in the radiosensitization of E. coli B/r by paracetamol.

Paracetamol, a widely-used analgestic and antipyretic drug, sensitized E. coli B/r to 60Co gamma-rays under hypoxic conditions. Part of the sensitizing effect has been shown to be due to an electron adduct of the drug. Paracetamol inhibited both post-irradiation DNA and protein syntheses. The targets involved in the inhibition of post-irradiation DNA synthesis have been shown to be different in the presence of the sensitizer. Increased DNA degradation after irradiation was also observed when E. coli B/r were irradiated in the presence of the drug. The presence of paracetamol during hypoxic irradiation of E. coli B/r resulted in the enhancement of DNA single-strand scissions with no apparent effect on their rejoining.

Acetaminophen↗

PubMed1975

A fixed drug eruption due to paracetamol.

A fixed drug eruption due to paracetamol is reported. Over 10,000,000 prescriptions (EC10) for paracetamol are issued annually and rashes occurring as possible adverse reactions to this drug are reported fairly frequently to the Committee on Safety of Medicines (Committee on Safety of Medicines-personal communication). These include urticaria, angioneurotic oedema, purpura, morbilliform and scarlatiniform rashes, erythema nodosum, eczema, alopecia and nail changes but in many of these cases the cause-effect relationship is unproven. One strongly suspected case (Savin, 1970) was reported from St John's Hospital. This was a patient who developed a fixed drug rash after taking a chlormezanone-paracetamol combination. However, no other reports of a fixed drug rash which was proved to be due to parcetamol have been found.

Acetaminophen↗