Diabetes mellitus, obstructive uropathy and urinary infection were considered to be most important in the etiology of renal papillary necrosis in the past literature. However, since 1953, Spuhler and Zollinger reported an association between phenacetin abuse and renal papillary necrosis, the most frequent cause of renal papillary necrosis has been diabetes mellitus, while analgesic abuse (contained phenacetin) has been the second most common factor in recent reports. In the more recent literature, most of the patient have had neither obstructive uropathy nor urinary infection, and it is quite possible that there two condition are of no direct etiological significance. But in this case, we can not suggest definite etiological factor except urinary infection clinically. Only one case is reported showing clinical manifestations laboratory findings, pyelographic findings and pathological changes compare with previous papers.
Diabetes Mellitus ; Humans ; Necrosis* ; Phenacetin

P450 1A2 is responsible for the metabolism of clinically important drugs and the metabolic activation of environmental chemicals. Genetic variations of P450 1A2 can influence its ability to perform these functions, and thus, this study aimed to characterize the functional significance of three P450 1A2 allelic variants containing nonsynonymous single nucleotide polymorphisms (P450 1A2*8, R456H; *15, P42R; *16, R377Q). Variants containing these SNPs were constructed and the recombinant enzymes were expressed and purified in Escherichia coli. Only the P42R variant displayed the typical CO-binding spectrum indicating a P450 holoenzyme with an expression level of approximately 170 nmol per liter culture, but no P450 spectra were observed for the two other variants. Western blot analysis revealed that the level of expression for the P42R variant was lower than that of the wild type, however the expression of variants R456H and R377Q was not detected. Enzyme kinetic analyses indicated that the P42R mutation in P450 1A2 resulted in significant changes in catalytic activities. The P42R variant displayed an increased catalytic turnover numbers (k(cat)) in both of methoxyresorufin O-demethylation and phenacetin O-deethylation. In the case of phenacetin O-deethylation analysis, the overall catalytic efficiency (k(cat)/K(m)) increased up to 2.5 fold with a slight increase of its K(m) value. This study indicated that the substitution P42R in the N-terminal proline-rich region of P450 contributed to the improvement of catalytic activity albeit the reduction of P450 structural stability or the decrease of substrate affinity. Characterization of these polymorphisms should be carefully examined in terms of the metabolism of many clinical drugs and environmental chemicals.
Biotransformation ; Blotting, Western ; Cytochrome P-450 CYP1A2* ; Escherichia coli ; Genetic Variation ; Metabolism ; Phenacetin ; Polymorphism, Single Nucleotide

We developed an ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for the determination of acetaminophen concentration in human plasma. Following protein precipitated extraction, the analytes were separated and analyzed using an UPLC-MS/MS in the multiple reaction monitoring (MRM) mode with the respective [M+H]+ ions, m/z 152.06 → 110.16 for acetaminophen and m/z 180.18 → 138.12 for phenacetin (internal standard, IS). The method showed a linear response from 1 to 100 µg/mL (r > 0.9982). The limit of quantitation for acetaminophen in plasma was 1 µg/mL. The intra- and inter-day accuracy ranged in the ranges of 94.40–99.56% and 90.00–99.20%, respectively. The intra- and inter-day precision ranged in the ranges of 2.64–10.76% and 6.84–15.83%, respectively. This method was simple, reliable, precise and accurate and can be used to determine the concentration of acetaminophen in human plasma. Finally, this fully validated method was successfully applied to a pharmacokinetic study of acetaminophen in healthy volunteers following oral administration.
Acetaminophen* ; Administration, Oral ; Healthy Volunteers ; Humans* ; Ions ; Mass Spectrometry ; Phenacetin ; Plasma*

Following a report by Hultengren et al. (Acta Chir Scand, 1965), it has been suggested that analgesic abuse predisposes to urothelial neoplasia. Urinary tract malignancy is combined in 8-10% of patients with analgesic nephropathy. Microscopic or gross hematuria can be the first sign leading to the diagnosis of uroepithelial malignanacy in analgesic abusers. Since uroepithelial malignancies found in analgesic abusers tend to be multiple and have a worse prognosis, continued monitoring is essential, and new hematuria should be evaluated with urinary cytology, and cystoscopy with reterograde pyelography. Phenacetin found to be the chief cause of malignancies in analgesic abusers, it has been anticipated to be a human carcinogen and was banned as an OTC drug since 1987. But still there remains a debate whether acetaminophen and other compound analgesic components are carcinogenic. We report the case of a 58-year-old man with a history of analgesic abuse who was diagnosed with transitional cell carcinoma combined with analgesic nephropathy. We also review the literature.
Acetaminophen ; Analgesics ; Carcinoma, Transitional Cell* ; Cystoscopy ; Diagnosis ; Hematuria ; Humans ; Middle Aged ; Nephritis, Interstitial ; Phenacetin ; Prognosis ; Ureter* ; Urinary Tract ; Urography

The study comprises 127 inpatients with drug eruption, treated at the Department of Dermatology, Seoul National University Hospital, during a 10-year period. The results are summarized as follows: 1. Out of 1,434 dermatologic inpatients, 127(8. 9%) patients were diagnosed as drug eruption. 2. The cutaneous manifestations of drug eruptions in the order of frequency were as follows: exanthematous eruption, urticaria, erythema multiforme, Stevens Johnson syndrome, TEN, exfoliative dermatitis, fixed drug eruption and purpura. 3. Antibiotics and antimicrobials were the most common causative agents followed by antipyretics and analgesics, CNS depressant drugs and herb drugs. 4. The 5 most common drugs causing drug eruptions were ampicillin, acetyl salicylic acid, diphenylhydantoin, sulfonamide and phenacetin.
Ampicillin ; Analgesics ; Anti-Bacterial Agents ; Antipyretics ; Dermatitis, Exfoliative ; Dermatology ; Drug Eruptions* ; Erythema Multiforme ; Humans ; Inpatients ; Phenacetin ; Phenytoin ; Purpura ; Salicylic Acid ; Seoul ; Stevens-Johnson Syndrome ; Urticaria

OBJECTIVETo investigate phase I and phase II enzyme activities in drug metabolism with tissue-like cultures of rat hepatocytes.

METHODSThe gel entrapment and spheroid culture of hepatocytes were used as tissue-like cultures and the monolayer culture was used as a control. The metabolism of phenacetin and 7-hydroxycoumarin (7-HC) was evaluated as the activities of phase I and phase II enzymes after incubated in medium for a period of time. The metabolites were assayed by HPLC. The hepatocytes were exposed to beta-naphthoflavone (BNF, 50 micromol x L(-1)) before the phase I and phase II enzyme activities were analyzed.

RESULTIn monolayer culture, phase I parameters decreased quickly and did not detected at d 5, and the phase II enzyme activities were not detected at d 7. In other two models of tissue-like cultures, the activities of phase I and phase II enzyme maintained at 32%-50% of the initial value at d 7. Paracetamol formation rates in spheroid culture maintained at 96% of that at d 1. The phase I enzyme activities of the spheroid culture were maintained from d 1 to d 3 at a level of 2.7-3.9-fold higher than the monolayer culture. After exposure to BNF the activities on phase I enzyme increased by about 2.5-fold (P <0.05) in all three culture models, while the increase in phase II enzyme was not significant.

CONCLUSIONThe gel entrapment culture and spheroid culture are superior to the monolayer culture in maintenance of drug metabolic enzyme activities.

Animals ; Cells, Cultured ; Cytochrome P-450 Enzyme System ; metabolism ; Enzyme Activation ; Female ; Hepatocytes ; cytology ; Male ; Phenacetin ; metabolism ; Rats ; Rats, Sprague-Dawley ; Umbelliferones ; metabolism ; beta-Naphthoflavone ; pharmacology

OBJECTIVETo investigate the effect of CYP450 enzyme inhibition of berberine in pooled human liver microsomes by cocktail probe drugs.

METHODCocktail probe drugs method has been established, an LC-MS/MS analytical method has been established to determine the five probes of midazolam, phenacetin, dextromethorphan, tolbutamide, chlorzoxazone and the internal standard was benzhydramine to evaluate the effect of CYP450 activity following administration of berberine in pooled human liver microsomes.

RESULTCompared with control group, the pharmacokinetics of midazolam, phenacetin and tolbutamide were no significant differences, but the pharmacokinetics of chlorzoxazone was significantly decreased. There were no significant differences for the pharmacokinetics of dextromethorphan when the concentration of berberine was 50 microg x L(-1). The pharmacokinetics of dextromethorphan was significantly decreased when the concentration of berberine was exceed 200 microg x L(-1).

CONCLUSIONBerberine has no influence on the activities of CYP3A4, CYP1A2 and CYP2C19 below 2 000 microg x L(-1), but can inhibit the activity of CYP2E1 and CYP2D6 in concentration-dependent.

Berberine ; pharmacology ; Chlorzoxazone ; pharmacokinetics ; Cytochrome P-450 Enzyme Inhibitors ; Dextromethorphan ; pharmacokinetics ; Dose-Response Relationship, Drug ; Humans ; Microsomes, Liver ; enzymology ; Midazolam ; pharmacokinetics ; Phenacetin ; pharmacokinetics ; Tolbutamide ; pharmacokinetics

Drug-drug interactions have become a serious problem in the clinic, since plant-based medicines are extensively used. The present study investigated the effects of Ziziphus jujuba fruit (ZJ) extract on the pharmacokinetics of phenacetin, a typical substrate of a cytochrome P450 enzyme CYP 1A2, in rats. The rats were pretreated with the water extract (1.0 g · kg(-1)) or the ethanolic extract (3.6 g · kg(-1)) of ZJ for 10 days, and the pharmacokinetics of phenacetin was investigated after intravenous administration. In an in vitro assay, acetaminophen formation in the hepatic microsomes of ZJ-treated rats was investigated to assess CYP1A2 activity. Our results demonstrated that the treatment with the water and ethanolic extracts of ZJ decreased the plasma concentration of phenacetin and increased the plasma concentration of acetaminophen, resulting in a 43.2% and 15.5% reduction in the AUC0-120 of phenacetin, respectively, and a 53.2% and 64.9% increase in the AUC0-120 of acetaminophen, respectively after intravenous administration. The water or ethanolic extract of ZJ significantly increased the clearance of phenacetin and acetaminophen formation in hepatic microsomes. In conclusion, ZJ extracts displayed effects on the pharmacokinetics of phenacetin and increased the CYP1A2 activity in rats. Therefore, precaution on drug-drug interactions should be taken when ZJ is co-administered with drugs metabolized by CYP1A2, which may result in decreased concentrations of these drugs.
Acetaminophen ; metabolism ; Animals ; Area Under Curve ; Cytochrome P-450 CYP1A2 ; Cytochromes ; metabolism ; Fruit ; Herb-Drug Interactions ; Liver ; drug effects ; Male ; Microsomes, Liver ; Phenacetin ; metabolism ; pharmacokinetics ; Plant Extracts ; pharmacology ; Rats, Sprague-Dawley ; Ziziphus