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Abstract
The saliva/plasma concentration ratio of fluconazole was investigated in 22 HIV-1-infected individuals with an oropharyngeal Candida infection to determine whether saliva fluconazole concentrations could provide useful information for therapeutic drug monitoring in this population. Steady-state paired plasma and saliva samples were obtained after approximately 1 week of treatment with 50-or 100-mg fluconazole as capsules. A significant correlation between plasma and salivary levels of fluconazole was observed. The median saliva/plasma concentration ratio was 1.3 and was independent of the ingested dose and the plasma fluconazole concentration. The prediction of fluconazole concentrations in plasma from the concentrations in saliva was, although unbiased, not precise. From these findings, the authors conclude that although stimulated salivary fluconazole concentrations are significantly correlated with plasma concentrations, it is not possible to predict plasma fluconazole levels from the salivary concentrations with adequate precision. However, saliva fluconazole concentrations have sufficient value to test for compliance and even semiquantitative prediction of plasma concentrations.
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Affiliation(s)
- C H Koks
- Department of Pharmacy and Pharmacology, Slotervaart Hospital, Amsterdam, The Netherlands.
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2
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Koks CH, Crommentuyn KM, Hoetelmans RM, Burger DM, Koopmans PP, Mathôt RA, Mulder JW, Meenhorst PL, Beijnen JH. The effect of fluconazole on ritonavir and saquinavir pharmacokinetics in HIV-1-infected individuals. Br J Clin Pharmacol 2001; 51:631-5. [PMID: 11422025 PMCID: PMC2014488 DOI: 10.1046/j.0306-5251.2001.01409.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AIMS To study the effect of fluconazole on the steady-state pharmacokinetics of the protease inhibitors ritonavir and saquinavir in HIV-1-infected patients. METHODS Five subjects treated with saquinavir and three with ritonavir received the protease inhibitor alone (saquinavir 1200 mg three times daily, ritonavir 600 mg twice daily) on day 1, and the same protease inhibitor in combination with fluconazole (400 mg on day 2 and 200 mg on days 3 to 8). Pharmacokinetic parameters were determined on days 1 and 8. RESULTS In the saquinavir group, the median increase in the area under the plasma concentration vs time curve was 50% from 1800 microg l(-1) h to 2700 microg l(-1) h (P = 0.04, median increase: 900 microg l(-1) h; 2.5 and 97.5 percentile: 500-1300), and 56% for the peak concentration in plasma (from 550 to 870 microg l(-1), P = 0.04; median increase: 320 microg l(-1) h, 2.5 and 97.5 percentile: 60-450 microg l(-1)). In the ritonavir group, there were no detectable changes in the pharmacokinetic parameters on addition of fluconazole. CONCLUSIONS Because of the favourable safety profile of saquinavir, dose adjustments are probably not necessary with concomitant use of fluconazole, as is the case for ritonavir.
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Affiliation(s)
- C H Koks
- Department of Pharmacy and Pharmacology, Slotervaart Hospital, Amsterdam, The Netherlands.
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3
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Koks CH, van Heeswijk RP, Veldkamp AI, Meenhorst PL, Mulder JW, van der Meer JT, Beijnen JH, Hoetelmans RM. Itraconazole as an alternative for ritonavir liquid formulation when combined with saquinavir. AIDS 2000; 14:89-90. [PMID: 10714572 DOI: 10.1097/00002030-200001070-00011] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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4
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Abstract
Digoxin, which has a very narrow therapeutic window, is one of the most commonly prescribed drugs in the treatment of congestive heart failure. In some cases of atrial fibrillation digoxin is used in combination with verapamil. Verapamil can increase the plasma concentration of digoxin up to 60-90%. So far the precise mechanism of this pharmacokinetic drug-drug interaction is not known. Many studies suggest that verapamil reduces the renal clearance of digoxin. The energy-dependent membrane-bound transport enzyme, P-glycoprotein, may also be involved. Reports from oncology research show that verapamil can interact with P-glycoprotein as a modulator. Also taking into account that digoxin, like many anticancer drugs, is a substrate for P-glycoprotein, it is likely that P-glycoprotein modulation accounts for the digoxin-verapamil interaction. Current knowledge suggest that the non-competitive digoxin-verapamil interaction is due to inhibition of P-glycoprotein activity by verapamil resulting in a decreased renal tubular elimination of digoxin.
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Affiliation(s)
- M Verschraagen
- Department of Medical Oncology, University Hospital Vrije Univrsiteit
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5
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Bronner GM, Koks CH, Beijnen JH. [Thalidomide once more in the spotlight]. Ned Tijdschr Geneeskd 1999; 143:122. [PMID: 10086119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
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6
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Abstract
INTRODUCTION The toxicity profile of the amphetamine derivative 3,4-methylenedioxymethamphetamine (MDMA, "Ecstasy") is well known. This designer drug is usually taken at "house parties" and may cause severe complications, sometimes leading to death, even when taken in relatively small units (1 or 2 tablets). Up to now, only a few cases of survival after ingestion of an overdose of Ecstasy have been described. In most cases the users developed hyperthermia, disseminated intravascular coagulation, rhabdomyolysis, and renal failure. CASE REPORT We describe a man who, after ingesting 50 tablets of Ecstasy (in combination with oxazepam and alcohol) at home, recovered within 2 days. Presenting features were unconsciousness, apnea, and convulsions. It is suggested that in most cases severe 3,4-methylenedioxymethamphetamine toxicity results from an interaction between direct pharmacological effects of the drug and the prevailing environmental conditions (high ambient temperature, dancing in trance, little fluid intake).
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Affiliation(s)
- S Ramcharan
- Slotervaart Hospital, Amsterdam, The Netherlands
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7
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Huitema AD, Soesan M, Meenhorst PL, Koks CH, Beijnen JH. A dose-dependent delayed hypersensitivity reaction to acetaminophen after repeated acetaminophen intoxications. Hum Exp Toxicol 1998; 17:406-8. [PMID: 9726538 DOI: 10.1177/096032719801700708] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We report a case of a 29-year-old woman with a borderline personality disorder who presented with intentional substantial acetaminophen (paracetamol) overdosage on nine occasions during a period of 21 months. In most cases, the patient presented at the hospital within 4 h after ingestion and was treated with gastric lavage, activated charcoal, laxatives and intravenous N-acetylcysteine. During the sixth overdosage the patient developed a rash on her chest and shoulders which was considered an anaphylactoid reaction to N-acetylcysteine. Therefore she was treated with oral methionine subsequently, but developed the rash again. The rash was then ascribed to the repeated high-doses of acetaminophen and treatment with N-acetylcysteine was reinstituted. This case shows that when an anaphylactoid reaction occurs after an acetaminophen overdose and treatment with N-acetylcysteine, acetaminophen must also be taken into account as the cause of the anaphylactoid reaction before effective therapy with N-acetylcysteine is withheld.
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Affiliation(s)
- A D Huitema
- Slotervaart Hospital, Department of Pharmacy and Pharmacology, Amsterdam, The Netherlands
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8
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Hoetelmans RM, Meenhorst PL, Mulder JW, Burger DM, Koks CH, Beijnen JH. Clinical pharmacology of HIV protease inhibitors: focus on saquinavir, indinavir, and ritonavir. Pharm World Sci 1997; 19:159-75. [PMID: 9297727 DOI: 10.1023/a:1008629608556] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
In this review the clinical pharmacology of HIV protease inhibitors, a new class of antiretroviral drugs, is discussed. After considering HIV protease function and structure, the development of inhibitors of HIV protease is presented. Three protease inhibitors are reviewed in more detail: saquinavir, indinavir, and ritonavir. Clinical trial results with these agents are evaluated. Furthermore, adverse effects, resistance, dosage and administration, clinical pharmacokinetics, pharmacokinetic-pharmacodynamic relationships, and drug interactions are discussed.
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Affiliation(s)
- R M Hoetelmans
- Department of Pharmacy & Pharmacology, Slotervaart Hospital, Amsterdam, The Netherlands
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9
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Hoetelmans RM, Kraaijeveld CL, Meenhorst PL, Mulder JW, Burger DM, Koks CH, Beijnen JH. Penetration of 3'-amino-3'-deoxythymidine, a cytotoxic metabolite of zidovudine, into the cerebrospinal fluid of HIV-1-infected patients. J Acquir Immune Defic Syndr Hum Retrovirol 1997; 15:131-6. [PMID: 9241112 DOI: 10.1097/00042560-199706010-00006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The penetration of 3'-amino-3'-deoxythymidine (AMT) into the cerebrospinal fluid (CSF) of HIV-1-infected patients has been investigated. In 23 patients who used zidovudine (ZDV) chronically, CSF and plasma samples were assayed for AMT and ZDV. The influences of time between ZDV oral administration and lumbar puncture, of ZDV dose, and of the medical indication for lumbar puncture based on the concentration of AMT in CSF and on the CSF-plasma concentration ratio were investigated. AMT can be detected in the CSF after oral administration of ZDV; concentrations of AMT in CSF ranged from 0.75 to 4.8 ng/ml (median, 1.7 ng/ml). The median CSF-plasma concentration ratio was 1, and equaled that for ZDV. CSF and plasma concentrations of AMT were approximately threefold higher in patients with cerebral toxoplasmosis; the CSF-plasma concentration ratio remained equal to unity in these cases. This phenomenon might be caused by a pharmacokinetic interaction between AMT and pyrimethamine, sulfadiazine, folinic acid, or a combination of these. The clinical relevance of AMT, especially the possibility of decreased efficacy of ZDV, throughout the body and in the central nervous system, and the involvement of this metabolite in ZDV-induced myelosuppression, remains to be established.
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Affiliation(s)
- R M Hoetelmans
- Department of Pharmacy, Slotervaart Hospital, Amsterdam, The Netherlands
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10
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Abstract
Etoposide (Vepesid) is a widely used drug in a variety of neoplasms. To improve the pharmaceutical characteristics of etoposide, etoposide phosphate (Etopophos, Bristol-Myers Squibb) has been developed as a prodrug. Etoposide phosphate is the phosphate ester derivative of etoposide. In comparison to the parent compound, etoposide phosphate is highly soluble in water and can be readily formulated for intravenous use, resulting in higher clinical application. This paper presents information on the pharmaceutical properties and the current status of etoposide phosphate in clinical trials.
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Affiliation(s)
- A H Witterland
- Dept. of Pharmacy, Slotervaart Hospital/Netherlands Cancer Institute, Amsterdam
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Abstract
We report clinical findings and pharmacokinetic data regarding a combined dapsone and clofazimine intoxication in a man, who ingested 50 tablets of dapsone (100 mg) 20 capsules of clofazimine (100 mg) and two tablets of rifampicin (600 mg). Oral administration of activated charcoal (50 grams) and sodium sulphate (20 grams) after gastric lavage resulted in an elimination half-life in plasma of 11.1 and 10.8 h for dapsone and its main metabolite, monoacetyldapsone, respectively. A rapid initial decrease of the plasma concentration of clofazimine was observed after gastric lavage and administration of activated charcoal and sodium sulphate. 15 h after this treatment, clofazimine plasma levels remained relatively constant. Dapsone-induced methaemoglobinaemia (48% at admission) was treated successfully with methylene blue.
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Affiliation(s)
- R M Hoetelmans
- Department of Pharmacy, Slotervaart Hospital, Amsterdam, The Netherlands
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12
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Koks CH, Meenhorst PL, Hillebrand MJ, Bult A, Beijnen JH. Pharmacokinetics of fluconazole in saliva and plasma after administration of an oral suspension and capsules. Antimicrob Agents Chemother 1996; 40:1935-7. [PMID: 8843308 PMCID: PMC163444 DOI: 10.1128/aac.40.8.1935] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The concentrations of fluconazole were determined at steady state in the saliva and plasma of 10 healthy volunteers after ingestion of fluconazole as capsules and after flushing the mouth for 2 min with the same dose formulated as an oral suspension and swallowing of the drug. Saliva and plasma samples were analyzed by a validated high-performance liquid chromatographic assay. Flushing and swallowing of the oral suspension resulted in a significantly (P = 0.005) higher mean area under the concentration-versus-time curve (AUC) from 0 to 24 h in saliva (89.13 +/- 23.42 mg.h/liter) than that obtained after ingestion of the same dose as capsules (69.27 +/- 12.89 mg . h/liter). The calculated mean maximum concentration in saliva just after swallowing of the suspension was 97.99 +/- 6.12 mg/liter. The peak fluconazole concentration in saliva after the ingestion of the capsules was 3.55 +/- 0.40 mg/liter. The fluconazole oral suspension and capsules resulted in comparable concentrations and AUCs in plasma. Thus, because of a higher local level of drug exposure in terms of both higher peak concentrations in saliva and a higher salivary AUC, the fluconazole oral suspension has theoretical advantages over the capsule formulation in the treatment of oropharyngeal candidiases.
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Affiliation(s)
- C H Koks
- Department of Pharmacy, Slotervaart Hospital, Amsterdam, The Netherlands
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Burger DM, Kraayeveld CL, Meenhorst PL, Mulder JW, Hoetelmans RM, Koks CH, Beijnen JH. Study on didanosine concentrations in cerebrospinal fluid. Implications for the treatment and prevention of AIDS dementia complex. Pharm World Sci 1995; 17:218-21. [PMID: 8597780 DOI: 10.1007/bf01870615] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
It has been hypothesized that didanosine has a low efficacy in the prevention and treatment of patients with the dementia complex of acquired immunodeficiency syndrome (AIDS) because "... the drug has not been detected in the cerebrospinal fluid". We investigated didanosine concentrations in cerebrospinal fluid (CSF) and plasma of four patients with AIDS who were using didanosine chronically. Didanosine levels, 4 h after the last drug administration, averaged 0.16 (+/- 0.03) mumol/l in CSF and 0.70 (+/- 0.27) mumol/l in plasma. When compared with historical data from patients using zidovudine, didanosine concentrations in CSF appeared to be approximately half (on a molar base) those of zidovudine concentrations in the CSF. Whether this difference in CSF levels is the explanation for the presumed lower efficacy of didanosine in the prevention and treatment of AIDS dementia complex remains to be proven. However, it is clear from this study, in contrast with earlier suggestions, that didanosine is able to pass the blood-CSF barrier in human immunodeficiency virus-infected individuals.
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Affiliation(s)
- D M Burger
- Department of Pharmacy, Slotervaart Hospital, Amsterdam, The Netherlands
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14
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Abstract
With the commercial availability of a cream (EMLA) containing a eutectic mixture of local anaesthetics, 2.5% (w/w) lidocaine and 2.5% (w/w) prilocaine, effective topical anaesthesia of the intact skin is possible without the need for subcutaneous injections or exposure to high concentrations of local anaesthetics. In our hospital a topical anaesthetic product was designed for the same purpose. The home-made product contains a eutectic mixture of a local anaesthetic (5% w/w) and l-menthol (1% w/w). Prilocaine was used as the local anaesthetic because it is known for its safety and its well investigated analgesic effects. The eutectic mixture of prilocaine and l-menthol was mixed with a carbopol hydrogel (1% w/w). Preliminary testing of this anaesthetic hydrogel in our hospital has yielded satisfactory results. The anaesthetic hydrogel was found to be stable after at least 3 months' storage at ambient temperature.
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Affiliation(s)
- Y L Nortier
- Department of Pharmacy, Slotervaart Hospital, Amsterdam, The Netherlands
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15
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Koks CH, Rosing H, Meenhorst PL, Bult A, Beijnen JH. High-performance liquid chromatographic determination of the antifungal drug fluconazole in plasma and saliva of human immunodeficiency virus-infected patients. J Chromatogr B Biomed Appl 1995; 663:345-51. [PMID: 7735482 DOI: 10.1016/0378-4347(94)00445-b] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
A high-performance liquid chromatographic (HPLC) assay has been developed for the determination of the antifungal drug fluconazole in saliva and plasma of patients infected with the human immunodeficiency virus (HIV). Samples can be heated at 60 degrees C for 30 min to inactivate the virus without loss of the analyte. The sample pretreatment involves a liquid-liquid extraction with chloroform-1-propanol (4:1, v/v). The chromatographic analysis is performed on a Lichrosorb RP-18 (5 microns) column by isocratic elution with a mobile phase of 0.01 M acetate buffer (pH 5.0)-methanol (70:30, v/v) and ultraviolet (UV) detection at 261 nm. The lower limit of is 100 ng/ml in plasma (using 500-microliters samples) and 1 microgram/ml in saliva (using 250-microliters samples) and the method is linear up to 100 micrograms/ml in plasma and saliva. At a concentration of 5 micrograms/ml the within-day and between-day precision in plasma are 7.1 and 5.7%, respectively. In saliva the within-day and between-day precision is 10.8% (at 5 micrograms/ml). The methodology is now being used in pharmacokinetic studies in HIV-infected patients in our hospital.
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Affiliation(s)
- C H Koks
- Department of Pharmacy, Slotervaart Hospital, Amsterdam, Netherlands
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16
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Burger DM, Meenhorst PL, Mulder JW, Kraaijeveld CL, Koks CH, Bult A, Beijnen JH. Therapeutic drug monitoring of phenytoin in patients with the acquired immunodeficiency syndrome. Ther Drug Monit 1994; 16:616-20. [PMID: 7878704 DOI: 10.1097/00007691-199412000-00015] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Serum phenytoin concentrations were investigated in 109 serum samples from 21 patients with the acquired immunodeficiency syndrome (AIDS) and in 1,231 serum samples from 557 control subjects during phenytoin therapy. Total phenytoin concentrations were significantly lower in patients with AIDS than in the reference population (8.8 +/- 0.7 mg/L (mean +/- SE) vs. 10.6 +/- 0.2 mg/L), although phenytoin doses were significantly higher in the AIDS patients. Body weight and the use of folic acid were negatively related to phenytoin concentrations, whereas use of clarithromycin resulted in higher phenytoin levels. Zidovudine did not influence phenytoin levels. Calculation of the Michaelis-Menten parameters showed that Vmax values were similar in seven human immunodeficiency virus (HIV)-infected patients as compared with 12 controls, but a nonsignificant trend of lower Km values in the HIV-positive group was observed. Measurement of free phenytoin concentrations demonstrated that the fraction of unbound drug was increased in patients with AIDS. Hypoalbuminemia was common in this population, which may complicate the interpretation of total phenytoin concentrations.
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Affiliation(s)
- D M Burger
- Department of Pharmacy, Slotervaart Hospital, Amsterdam, The Netherlands
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17
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Burger DM, Rosing H, ten Napel CH, Duyts T, Meenhorst PL, Mulder JW, Koks CH, Bult A, Beijnen JH. Application of a radioimmunoassay for determination of levels of zalcitabine (ddC) in human plasma, urine, and cerebrospinal fluid. Antimicrob Agents Chemother 1994; 38:2763-7. [PMID: 7695259 PMCID: PMC188282 DOI: 10.1128/aac.38.12.2763] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
A specific and sensitive radioimmunoassay for the determination of levels of zalcitabine in human plasma, urine, and cerebrospinal fluid has been developed. Commercially available radiolabel and antiserum (Sigma Chemicals) were used after dilution in assay buffer. Prior to the immunoassay, standard and patient samples were subjected to solid-phase extraction on silica columns in order to obtain purified samples. The lower limit of quantitation was determined to be 1 ng/ml. Intra- and interassay variations were less than 11% for a number of quality control samples of drug in plasma and urine. Results from parallelism studies with plasma and urine demonstrated that samples outside the standard range (1 to 30 ng/ml) could be diluted by blank plasma or assay buffer, respectively. A large number of related compounds and potentially coadministered drugs were tested for cross-reactivity. Stability tests showed that heat treatment for 30 min at 60 degrees C or storage for 1 month at -30 degrees C did not affect zalcitabine concentrations in plasma or urine. The radioimmunoassay with solid-phase extraction for sample cleanup discussed here has been successfully applied in a pharmacokinetic study of a single patient, demonstrating its applicability for clinical pharmacokinetic research with zalcitabine.
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Affiliation(s)
- D M Burger
- Department of Pharmacy, Slotervaart Hospital, Amsterdam, The Netherlands
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18
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Burger DM, Meenhorst PL, ten Napel CH, Mulder JW, Neef C, Koks CH, Bult A, Beijnen JH. Pharmacokinetic variability of zidovudine in HIV-infected individuals: subgroup analysis and drug interactions. AIDS 1994; 8:1683-9. [PMID: 7888117 DOI: 10.1097/00002030-199412000-00007] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
OBJECTIVE To investigate determinants of inter- and intraindividual variability of zidovudine (ZDV) pharmacokinetics in HIV-infected patients. DESIGN A prospective study in a general 525-bed hospital with special funding for treatment and research of HIV-infected patients. METHODS Serial blood samples were collected from 68 HIV-infected individuals providing a total of 95 pharmacokinetic curves. ZDV was measured with high-performance liquid chromatography and radioimmunoassay. Pharmacokinetic parameters were calculated by non-compartmental analysis. Patient characteristics were investigated by multivariate analysis for an influence on ZDV pharmacokinetics. RESULTS Apparent ZDV clearance was significantly lower in patients with a lower body weight, in women, and in patients with a more advanced stage of HIV disease. Co-administration of methadone with ZDV resulted in higher plasma concentrations of ZDV, while rifampin and ganciclovir increased apparent ZDV clearance. Age, the duration of ZDV use, CD4+ cell count, creatinine clearance, elevated serum liver enzyme levels, and the use of 11 other co-administered medications were not independently related to apparent ZDV clearance. CONCLUSIONS The pharmacokinetic profile of ZDV in several subpopulations has been evaluated, as well as the observation of possible drug-drug interactions between ZDV and 14 different drugs or groups of drugs. These data suggest that patient-individualized antiretroviral therapy may be appropriate once pharmacokinetic-pharmacodynamic relationships have been established.
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Affiliation(s)
- D M Burger
- Department of Pharmacy, Slotervaart Hospital, Amsterdam, The Netherlands
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19
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Burger DM, Meenhorst PL, Underberg WJ, van der Heijde JF, Koks CH, Beijnen JH. Short-term, combined use of paracetamol and zidovudine does not alter the pharmacokinetics of either drug. Neth J Med 1994; 44:161-5. [PMID: 8028690 DOI: 10.1016/0300-2977(95)90002-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
OBJECTIVE To investigate a possible pharmacokinetic interaction between zidovudine and paracetamol. METHODS Six patients with AIDS took both zidovudine (AZT; 1000-1200 mg/day) and paracetamol (500 mg every 6 h) for 7 days. Pharmacokinetic monitoring was performed on day 0 (AZT alone) and after 7 days of combined use of paracetamol and AZT. RESULTS Combined use of paracetamol and AZT did not result in a significant change in any of the calculated pharmacokinetic parameters of AZT or its primary metabolite AZT-glucuronide. In addition, paracetamol pharmacokinetic parameters at day 7 did not differ from those usually reported in the literature. CONCLUSION Short-term, combined use of paracetamol and AZT does not lead to a change in the pharmacokinetics of either AZT or paracetamol. The effect of long-term use of this combination remains unknown. A recent case report of AZT-induced paracetamol hepatotoxicity [Am J Med 1992;93: 94-96] indicates that clinicians should still be aware of potential drug toxicity when prescribing both AZT and paracetamol.
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Affiliation(s)
- D M Burger
- Department of Pharmacy, Slotervaart Hospital, Amsterdam, Netherlands
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20
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Burger DM, Meenhorst PL, Koks CH, Beijnen JH. Pharmacokinetics of zidovudine and acetaminophen in a patient on chronic acetaminophen therapy. Ann Pharmacother 1994; 28:327-30. [PMID: 8193419 DOI: 10.1177/106002809402800306] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
OBJECTIVE To report a case of a potential interaction between acetaminophen and zidovudine in a patient who had used high daily doses of acetaminophen over many years. CASE SUMMARY A 43-year-old man presented with HIV-1 infection, recurrent oral candidiasis, and chronic use of acetaminophen, codeine, and diazepam before he started zidovudine therapy. Although literature was available regarding short-term combined use of acetaminophen and zidovudine, information was lacking on zidovudine therapy and kinetics after long-term use of acetaminophen. Acetaminophen and zidovudine pharmacokinetics were determined on several occasions. The results showed extremely rapid absorption of both drugs (tmax the time to reach maximum concentration, 10-15 minutes for acetaminophen and 15-20 minutes for zidovudine) and, consequently, relatively high maximum plasma concentration (Cmax). No influence on other pharmacokinetic parameters of either drug could be detected. Because the effect of high Cmax values of zidovudine is unknown, the patient was treated with a third of the dose of zidovudine used at that time (zidovudine 100 mg q6h). No toxicity or opportunistic infections developed within the next 8 months, after which the patient died of a cause unrelated to HIV infection. DISCUSSION The observed pharmacokinetic profiles of both drugs are discussed and compared with two studies dealing with zidovudine therapy in combination with short-term use of acetaminophen and with a case report of acetaminophen-induced hepatotoxicity during concomitant use of zidovudine. CONCLUSIONS Long-term use of acetaminophen may accelerate the absorption of zidovudine. Although other causes cannot be ruled out, there was no influence on other pharmacokinetic parameters of zidovudine. No influence of zidovudine on acetaminophen concentrations was found. Combined use of zidovudine 100 mg q6h and acetaminophen 500 mg q4h appeared to be safe and effective for at least eight months.
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Affiliation(s)
- D M Burger
- Department of Pharmacy, Slotervaart Hospital, Amsterdam, The Netherlands
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Burger DM, Kraaijeveld CL, Meenhorst PL, Mulder JW, Koks CH, Bult A, Beijnen JH. Penetration of zidovudine into the cerebrospinal fluid of patients infected with HIV. AIDS 1993; 7:1581-7. [PMID: 8286068 DOI: 10.1097/00002030-199312000-00006] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
OBJECTIVE To investigate penetration of zidovudine (ZDV) into the cerebrospinal fluid (CSF) of HIV-infected patients for whom a lumbar puncture was indicated. DESIGN A prospective study. SETTING General 525-bed hospital with special funding for treatment and research of HIV-infected patients. PATIENTS, PARTICIPANTS Thirty-nine patients with a medical indication for lumbar puncture who used ZDV chronically were included in this study (50 samples in total). MAIN OUTCOME MEASURE Determination of ZDV and proteins in CSF and plasma samples. RESULTS CSF concentrations of ZDV showed little fluctuation 1-8 h after the last ingestion of ZDV. In contrast, plasma levels displayed large variability in this period and decreased exponentially over time. As a result, the CSF/plasma ratio increased linearly over time. No significant relation between the ZDV dose, neither the medical indication for lumbar puncture nor the protein ratio (as a measure for the integrity of the blood-brain barrier), and CSF levels of ZDV was found. The CSF/plasma ratio of ZDV did not give essential information on drug distribution into CSF. CONCLUSIONS Penetration of ZDV into the CSF appears to be independent of the dose (range, 200-1250 mg daily), which may be an explanation for the efficacy of low doses of ZDV in the prevention and treatment of HIV-related neurological diseases. ZDV levels were at steady-state during the first 6 h after ingestion. The CSF/plasma ratio of ZDV concentrations is not an appropriate marker for drug penetration into CSF.
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Affiliation(s)
- D M Burger
- Department of Pharmacy, Slotervaart Hospital, Amsterdam, The Netherlands
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Abstract
A potential pharmacokinetic interaction between rifampin (Rimactan, Rifadin) and zidovudine (AZT, Retrovir) was investigated in the population of human immunodeficiency virus-infected patients at our hospital. The results from four patients who were on long-term (> or = 6 months) combination therapy with zidovudine and rifampin are presented. In all cases of combined use of zidovudine and rifampin, a lower area under the plasma concentration-time curve (AUC) and, consequently, a higher apparent clearance of zidovudine were found, compared with a reference population of zidovudine users. Patients had a low to normal maximum concentration of zidovudine in plasma. Elimination half-lives were normal in all but one patient. Zidovudine glucuronide concentrations were determined in three patients and three control subjects. The patients all had relatively higher peak plasma concentrations and higher AUCs of zidovudine glucuronide than the control subjects. In one patient, zidovudine and zidovudine glucuronide were also measured 2.5 months after discontinuation of rifampin. The AUC of zidovudine increased by a factor of 2. These data are in agreement with an enzyme-inducing effect of rifampin on the glucuronidation of zidovudine. They indicate that long-term combination therapy of rifampin and zidovudine leads to increased clearance of zidovudine, which may have therapeutic consequences.
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Affiliation(s)
- D M Burger
- Department of Pharmacy, Slotervaart Hospital, Amsterdam, The Netherlands
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Keijer WJ, Burger DM, Neuteboom GH, Vrooland JL, Meenhorst PL, Koks CH, Beijnen JH. Ocular complications of the acquired immunodeficiency syndrome. Focus on the treatment of cytomegalovirus retinitis with ganciclovir and foscarnet. Pharm World Sci 1993; 15:56-67. [PMID: 8387852 DOI: 10.1007/bf01874084] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The most common ocular complication in patients with the acquired immunodeficiency syndrome (AIDS) is cytomegalovirus retinitis. Incidence figures vary from 20 to 76%. Patients with cytomegalovirus may suffer from mild visual impairment of one or both eyes, but as the disease progresses the retinitis will almost certainly lead to blindness. Although cytomegalovirus retinitis is not a life-threatening infection, it can largely diminish the patient's quality of life. Clinical trials for the treatment of cytomegalovirus retinitis with a number of antiviral drugs have resulted in two drugs of choice, ganciclovir and foscarnet. Both drugs have an initial efficacy with induction therapy of 80-90%, but maintenance therapy is always needed to prevent a relapse. To exclude systemic side-effects of ganciclovir, intravitreal administration has been investigated with good results. Combination therapy of foscarnet and ganciclovir may be worthwhile in resistant cytomegalovirus retinitis.
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Affiliation(s)
- W J Keijer
- Department of Pharmacy, Slotervaart Hospital, Amsterdam, The Netherlands
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Abstract
In this article the literature about didanosine, an antiretroviral drug, is reviewed. The mechanism of action, biochemical pharmacology, pharmacokinetics, and clinical results of phase-I trials are discussed. Serious adverse effects such as pancreatitis and peripheral neuropathy have occurred in these trials. An antiretroviral effect was observed in terms of an increase in CD4+ lymphocytes and a decrease in p24 antigen levels in HIV-infected individuals. Didanosine seems to be a promising drug against HIV infection, but knowledge about its clinical efficacy is scanty.
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Affiliation(s)
- R M Franssen
- Department of Pharmacy, Slotervaart Hospital, Amsterdam, The Netherlands
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Beijnen JH, Meenhorst PL, van Gijn R, Hazelager WA, Koks CH, Underberg WJ. Gas chromatographic analysis, with electron capture detection, of the antifungal drug fluconazole in microvolumes of human plasma. J Pharm Biomed Anal 1991; 9:1173-5. [PMID: 1822192 DOI: 10.1016/0731-7085(91)80063-f] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- J H Beijnen
- Department of Pharmacy, Slotervaart Hospital/Netherlands Cancer Institute, Amsterdam
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Koks CH, Van der Kam HJ, Brouwers JR. A simple high pressure liquid chromatographic method for the determination of fluorouracil to monitor patients on regional infusion for hepatic metastases. Pharm Weekbl Sci 1990; 12:154-7. [PMID: 2277762 DOI: 10.1007/bf01970157] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
A rapid and sensitive high pressure liquid chromatographic method has been developed for the routine monitoring in serum of the antineoplastic agent fluorouracil, during continuous intraportal administration. Serum spiked with internal standard, bromouracil, was gently shaken for 10 min with ethylacetate at an acidic pH. The evaporated extract was dissolved in the mobile phase containing potassium phosphate buffer. Assays were performed at ambient temperature on a Chrompack LiChrosorb RP 18 column (2 X 100 X 3.0 mm) equipped with a guard column. The retention time of fluorouracil was 2-6 min. The calibration curve was linear from 25 to 2,000 ng/ml. The coefficient of variation was less than or equal to 1.6% for within-run precision and less than or equal to 2.9% for day-to-day precision. The mean recovery of fluorouracil was 57%.
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Affiliation(s)
- C H Koks
- Department of Clinical Pharmacy and Pharmacokinetics, General Hospital De Tjongerschans, Heerenveen, The Netherlands
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Koks CH, Brouwers JR, Sleijfer DT. Regional infusion of fluoropyrimidines for hepatic metastases of colorectal cancer. Pharm Weekbl Sci 1988; 10:69-75. [PMID: 2969092 DOI: 10.1007/bf01962681] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Recent reports on regional chemotherapy for hepatic metastases of colorectal origin are reviewed. Because of reported side effects and lack of evidence for its superiority over conventional intravenous administration, intra-arterial administration of fluoropyrimidines cannot be advised for routine use, but should be restricted to centres participating in clinical trials on this subject.
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Affiliation(s)
- C H Koks
- Department of Clinical Pharmacy, General Hospital De Tjongerschans, Heerenveen, The Netherlands
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Janknegt R, Koks CH. Pharmacokinetic aspects during continuous ambulatory peritoneal dialysis: a literature review. Pharm Weekbl Sci 1984; 6:229-36. [PMID: 6393041 DOI: 10.1007/bf01954550] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Since its introduction some years ago continuous ambulatory peritoneal dialysis (CAPD) has proved to be a valuable alternative to haemodialysis in the treatment of uraemia. Factors contributing to the transport of solutes through the peritoneal membrane are discussed and the literature concerning the pharmacokinetic aspects of CAPD is reviewed.
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