Clinical Pharmacology & Therapeutics (2003) 73, P31–P31; doi:

Objective.-To investigate the potential for interactions involving drugs likely to be coadministered with frovatriptan.Background.-Frovatriptan is a new 5-hydroxytryptamine (5-HT)(1B/1D) agonist. Preclinical data suggest that the pharmacokinetic and pharmacological profile of frovatriptan may differ from that of the currently available triptans.Methods.-The potential for interactions between frovatriptan and other drugs was investigated using in vitro methods, studies in healthy volunteers, and retrospective analysis of data from phase I trials.Results.-In vitro, frovatriptan was principally metabolized by cytochrome P-450 (CYP) 1A2 but was found not to be an inhibitor or inducer of this or other CYP isoenzymes. Frovatriptan was only a weak inhibitor of monoamine oxidase at very high concentrations in vitro and was not a substrate for this enzyme (unlike some other triptans). Coadministration with moclobemide, at doses known to inhibit monoamine oxidase-A, did not affect the pharmacokinetics of frovatriptan. Binding to plasma proteins was low (15%), and binding to erythrocytes was moderate (60%) and unlikely to be a source of interaction with other drugs. The pharmacokinetics of frovatriptan were not affected by moderate alcohol intake. There were slight increases in area under the curve and maximum concentration on concomitant administration with the combined oral contraceptives, propranolol, and fluvoxamine; and slight decreases in these parameters on concomitant administration with ergotamine and in tobacco smokers; these findings were considered to have no clinical significance in view of frovatriptan's large therapeutic index (well tolerated at doses ranging from 2.5 to 40 mg). These effects can be attributed primarily to modification of CYP1A2 activity but their impact is limited, probably due to frovatriptan also undergoing renal clearance and the likely role of blood cell binding in controlling the amount of unbound drug available for elimination.Conclusions.-Because it has no inhibitory or inducing effect on CYP isoenzymes and is only slightly bound to plasma proteins, it is unlikely that frovatriptan will alter the pharmacokinetics of concomitantly administered drugs. Frovatriptan, therefore, appears to have a low risk of interaction with other drugs, and adjustments of dose are unlikely to be required when it is coadministered with other agents.

The effects of frusemide on the urinary excretion of dopamine and 5-hydroxytryptamine (5-HT) were investigated in eight healthy male subjects in a randomized, placebo-controlled, cross-over study. Frusemide produced the expected rise in urinary dopamine excretion but it did not affect 5-HT excretion when compared with placebo. The lack of an effect on 5-HT excretion in man contrasts with studies in the rat which have reported a marked increase in 5-HT excretion after administration of this loop diuretic.

1. Equimolar amounts of gamma-L-glutamyl-L-3,4-dihydroxyphenylalanine (gludopa) and gamma-L-glutamyl-5-hydroxy-L-tryptophan were infused separately and together in eight healthy, salt-replete male subjects in a placebo-controlled, cross-over study to investigate whether the administration of one amine precursor affects the renal metabolism of the other and to determine whether dopamine or 5-hydroxytryptamine would be generated preferentially. The overall effect on sodium excretion was also measured when both precursors were administered simultaneously. 2. Administration of gludopa was associated with marked increases in the urinary excretion of L-dopa, dopamine and 3,4-dihydroxyphenylacetic acid, together with a rise in the urinary excretion of sodium. gamma-L-Glutamyl-5-hydroxy-L-tryptophan, on the other hand, produced marked increases in the urinary excretion of 5-hydroxy-L-tryptophan, 5-hydroxy-tryptamine and 5-hydroxyindoleacetic acid, and this was accompanied by a slight, but non-significant, reduction in sodium excretion. About 27% of the infused dose of gludopa (on a molar basis) was recovered in the urine as dopamine whereas 15% of the given dose of gamma-L-glutamyl-5-hydroxy-L-tryptophan was excreted as 5-hydroxytryptamine. 3. The urinary excretion values of L-dopa, dopamine and 3,4-dihydroxyphenylacetic acid after the simultaneous infusion of gludopa and gamma-L-glutamyl-5-hydroxy-L-tryptophan were not significantly different from those observed after infusion of gludopa only. Similarly, the urinary excretion values of 5-hydroxy-L-tryptophan, 5-hydroxytryptamine and 5-hydroxy-indoleacetic acid during the co-infusion were similar to those measured after administration of gamma-L-glutamyl-5-hydroxy-L-tryptophan only. The net effect of the concomitant infusion of both glutamyl derivatives was an increase in urinary sodium excretion. 4. Our study in salt-replete individuals suggests that dopamine rather than 5-hydroxytryptamine was preferentially produced when equimolar amounts of their precursors were provided and that the natriuretic effect of dopamine, generated intrarenally from gludopa, was greater than the sodium retaining action of 5-hydroxytryptamine derived from gamma-L-glutamyl-5-hydroxy-L-tryptophan. Comparison of the urinary metabolite data after the separate and concomitant infusion of the two glutamyl compounds provided no evidence of competitive inhibition of synthesis of either amine.

Panitumumab is a new humanized anti-epidermal growth factor receptor (EGFR) monoclonal antibody (mAb) approved for the treatment of advanced colorectal cancer. There is an increase in the use of this drug due to a good response rate and possible secondary resection in advance colorectal cancer. Here we present 18F-FDG PET/CT imaging findings of cardiac arrhythmia in a patient receiving Panitumumab for the treatment of metastatic infiltrating rectal adenocarcinoma. Cardiotoxicity is a known adverse effect associated with Panitumumab. By far to our knowledge, no documented imaging findings for the same are available in the literature.

1. This randomized, placebo-controlled, cross-over study compared the relative effectiveness of gamma-L-glutamyl-5-hydroxy-L-tryptophan (glu-5-HTP) and gamma-L-glutamyl-L-tryptophan (glu-TRP) in terms of their ability to act as substrates for renal 5-hydroxytryptamine (5-HT) synthesis and their actions on urinary sodium excretion. 2. Urinary excretion of 5-HT and sodium were determined before, during and after 1 h intravenous infusion of an equimolar amount (45 nmol kg-1 min-1) of glu-5-HTP or glu-TRP or placebo in nine healthy male subjects. 3. Cumulative urinary 5-HT excretion over the 4 h after the start of glu-5-HTP infusion was 350-fold greater than that after placebo, and this was associated with a reduction in the urinary excretion of sodium. 4. In contrast, the urinary excretion values of 5-HT and sodium after administration of glu-TRP were not significantly different from those observed on the placebo day. 5. The marked increase in urinary 5-HT excretion and the retention of sodium after administration of glu-5-HTP have been demonstrated in previous studies and result from increased intrarenal generation of 5-HT. The absence of a rise in urinary excretion of 5-HT after glu-TRP infusion suggests that there was no significant conversion of this glutamyl compound to 5-HT within the kidney. As a result, there was no effect on urinary sodium excretion.

Six healthy male subjects received equimolar amounts of two 5-hydroxytryptamine (5-HT) precursors, 5-hydroxy-L-tryptophan (5-HTP) and gamma-L-glutamyl-5-hydroxy-L-tryptophan (glu-5-HTP), on two occasions in a randomised cross-over study. There were marked increases in urinary 5-HTP and 5-HT excretion after infusion of both compounds. Mean urinary excretion rate of 5-HT, which was < 0.7 nmol min-1 before dosing, rose to a peak value of 412 +/- 92 nmol min-1 at the end of 5-HTP infusion and 303 +/- 29 nmol min-1 after administration of glu-5-HTP. This occurred without significant changes in blood 5-HT levels measured in platelet-rich plasma. These findings provide further evidence that the increase in urine 5-HT after administration of both 5-HT precursors is largely due to 5-HT synthesised within the kidney.

BACKGROUND:Patients with the sleep apnoea/hypopnoea syndrome have increased salt and water excretion at night which has been reported to be associated with an increase in plasma levels of atrial natriuretic peptide (ANP). A study was performed to determine whether any rise in plasma ANP levels was related to nocturnal hypoxaemia.METHODS:Nine patients with sleep apnoea/hypopnoea syndrome were studied on two nights, one breathing air and the other 28% oxygen, the order being randomised. Venous levels of ANP, aldosterone, and renin activity were measured.RESULTS:No decrease in plasma ANP levels on oxygen was seen, and, indeed, there was no evidence of an overnight increase in ANP levels.CONCLUSION:Oxygen therapy does not diminish nocturnal plasma ANP levels in patients with sleep apnoea/hypopnoea syndrome.

1. The effects of inhibition of peripheral aromatic L-amino acid decarboxylase during infusion of the relatively renally selective 5-hydroxytryptamine (5-HT) prodrug, gamma-L-glutamyl-5-hydroxy-L-tryptophan (glu-5-HTP), were examined in eight healthy male subjects in a randomised, placebo-controlled, cross-over study. 2. Each subject received oral carbidopa (100 mg) or placebo followed, 1 h later, by a 60 min intravenous infusion of glu-5-HTP (16.6 micrograms kg-1 min-1) or placebo. 3. After administration of glu-5-HTP, cumulative urinary excretion of 5-HT was 430-fold greater than that after placebo, and was associated with a period of sodium retention. 4. Pretreatment with carbidopa substantially attenuated the increase in 5-HT excretion after glu-5-HTP and abolished its antinatriuretic effect. 5. These results are in keeping with the proposition that the antinatriuretic action of glu-5-HTP is dependent on its decarboxylation to 5-HT.

andweighing61.5 to 99.5 kg(mean71.3 kg),tookpartinthisrandomised,placebo-controlled, cross-over study. Theywere normalonclinical examinationandnone hadlaboratory evidence ofhepatic, renal orhaematological abnormality. Theywereonnomedica-tionforatleast2weeksbeforethestartofthestudyandnodrugsapartfromthestudymedicationswereallowedduring the experimental period. They refrained fromalcohol for 24 hbefore each study day. Thestudywasapprovedbythe MedicalandClinical OncologyEthics

1. The disposition and kinetics of p-aminohippuric acid (PAH) were studied in 27 healthy male volunteers, 10 healthy female volunteers and 10 patients with chronic renal impairment following rapid intravenous injection of 10 mg kg-1. In addition, the renal clearances of PAH and its metabolite N-acetyl-PAH were measured in 10 of the healthy male volunteers following conventional administration of PAH by loading dose and constant infusion, and in another eight during sequential 'step-up' and 'step-down' infusions intended to maintain low, medium and high plasma concentrations below the threshold for onset of saturation of tubular transport. 2. PAH was eliminated rapidly with a mean half-life of less than 30 min in the healthy volunteers and 72 min in the renal patients. The corresponding estimates for acetyl-PAH were 49 and 153 min. In both groups the rate of disappearance of PAH slowed progressively over the period of observation and there was no true log-linear terminal elimination phase. 3. In the healthy volunteers about 50% of the dose was excreted in the urine in 30 min with quantitative recovery in 3 h. In 8 h, 17% of the dose was recovered as acetyl-PAH. In the patients with renal impairment the 8 h recovery was only 83.6% of the dose with 26.9% of the total appearing as acetyl-PAH. 4. The volume of distribution (Vss) of PAH was 16-18 l in the healthy subjects and renal patients. Acetyl-PAH appeared to have a much larger distribution volume (mean 65.5 l in the healthy volunteers). 5. In the healthy volunteers the renal clearance of PAH fell dramatically from 599 +/- 115 ml min-1 1.73m-2 during the first hour after administration to 300 +/- 208 ml min-1 1.73 m-2 during the second hour (P < 0.001). The corresponding renal clearances of acetyl-PAH were 775 +/- 196 and 916 +/- 212 ml min-1 1.73 m-2. In the patients with renal impairment the renal clearance of PAH fell from 194 +/- 83 ml min-1 1.73 m-2 in the first hour to only 61 +/- 19 ml min-1 1.73 m-2 from 4 to 6 h. Over the same period there was no significant fall in the clearances of acetyl-PAH or total PAH (acetyl-PAH + PAH).(ABSTRACT TRUNCATED AT 400 WORDS)

1. The effects of 1 h intravenous infusions of equimolar amounts (45 nmol min-1 kg-1) of two putative 5-hydroxytryptamine renal prodrugs, 5-hydroxy-L-tryptophan and gamma-L-glutamyl-5-hydroxy-L-tryptophan, were investigated in a randomized, placebo-controlled, cross-over study in nine healthy male subjects. 2. Cumulative urinary 5-hydroxytryptamine excretion over the 3 h observation period rose by about 370-fold after 5-hydroxy-L-tryptophan and 390-fold after gamma-L-glutamyl-5-hydroxy-L-tryptophan when compared with placebo infusion. Urinary 5-hydroxy-L-tryptophan excretion was three times higher after administration of gamma-L-glutamyl-5-hydroxy-L-tryptophan than after 5-hydroxy-L-tryptophan infusion. Urinary 5-hydroxyindole-3-acetic acid excretion after 5-hydroxy-L-tryptophan infusion was significantly greater than that after gamma-L-glutamyl-5-hydroxy-L-tryptophan administration. Urinary dopamine excretion was not affected by either compound when compared with placebo. 3. 5-Hydroxy-L-tryptophan significantly reduced urine flow rate and urinary sodium excretion. gamma-L-Glutamyl-5-hydroxy-L-tryptophan was antinatriuretic but did not affect urine output. These changes occurred without significant alterations in effective renal plasma flow and glomerular filtration rate. 4. Both 5-hydroxy-L-tryptophan and gamma-L-glutamyl-5-hydroxy-L-tryptophan significantly increased plasma aldosterone concentration without a concomitant rise in plasma renin activity.(ABSTRACT TRUNCATED AT 250 WORDS)

1. Renal and systemic responses to infusion of angiotensin II (1.25 and 2.5 ng min-1 kg-1 body weight) were examined in ten normal males 12 h after single doses of 750 mg of lithium carbonate, 250 mg of lithium carbonate (n = 6) or placebo. 2. Baseline mean arterial pressure [mean (SEM)] was higher after 750 mg of lithium [93.1 (1.7) versus 89.5 (1.9 mmHg, P = 0.014], and the subsequent rise in blood pressure during angiotensin II infusion was lower [8.2 (1.8) versus 12.2 (2.4) mmHg, P less than 0.02]. 3. Lithium at a dose of 750 mg increased overnight urinary sodium excretion before the study. The fall in fractional sodium excretion during angiotensin II infusion was reduced after pretreatment with 750 mg of lithium [750 mg of lithium, 2.73 (0.24) to 1.34 (0.08)%; placebo, 2.69 (0.26) to 1.01 (0.11)%; P = 0.02]. The increases in effective filtration fraction [750 mg of lithium, 5.4 (1.0)%; placebo, 8.6 (0.7)%; P less than 0.05] and total effective renal vascular resistance [750 mg of lithium, 3700 (390) dyn s cm-5; placebo 5100 (460) dyn s cm-5; P = 0.03] during angiotensin II infusion were also attenuated after 750 mg of lithium. Responses after 250 mg of lithium did not differ from those after placebo. 4. The fall in plasma renin activity and the increase in plasma aldosterone concentration during angiotensin II infusion were similar on each study day. 5. Renal responses to exogenous angiotensin II are altered after pretreatment with a 750 mg dose of lithium in normal man. This dose of lithium is not an inert marker of sodium handling.

1. The effects of tenoxicam on renal function were studied in 10 patients with chronic renal failure (creatinine clearance 46.7 +/- 11.9 ml min-1 1.73 m-2) and eight healthy volunteers. A parallel treatment control group of eight healthy volunteers received placebo. Tenoxicam was given orally in a dose of 40 mg daily for 2 days followed by 20 mg daily for a further 8 days. Renal function was assessed by measurement of the renal clearances of inulin and p-aminohippurate (PAH) using the single injection technique before and during administration of tenoxicam. 2. In the healthy volunteers there were no changes in glomerular filtration rate, effective renal plasma flow, or the urinary excretion of N-acetylglucosaminidase and beta 2-microglobulin on the 3rd and 10th days of treatment with tenoxicam. The mean urinary excretion of prostaglandins E2 and 6-keto F1 alpha decreased during treatment but there was great individual variation and the differences were not statistically significant. Tenoxicam had no effect on the half-life, clearance, volume of distribution or urinary recovery of inulin and PAH. 3. There was no significant change in the clearance of inulin and creatinine after treatment with tenoxicam for 10 days in the patients with chronic renal failure. However, in this group there was a significant increase in plasma creatinine on the 3rd and 6th days with a return to pretreatment levels by the 10th day. The administration of tenoxicam for 10 days was associated with a small but significant increase in the plasma half-life and volume of distribution of inulin.(ABSTRACT TRUNCATED AT 250 WORDS)

Conference Abstract| March 01 1991 Effect of Lithium on Systemic and Renal Responses to Angiotensin II Infusion in Normal Man D.W. Eadington; D.W. Eadington 1Medical Renal Unit and Clinical Pharmacology Unit, Royal Infirmary, Edinburgh, EH3 9YW Search for other works by this author on: This Site PubMed Google Scholar S. Freestone; S. Freestone 1Medical Renal Unit and Clinical Pharmacology Unit, Royal Infirmary, Edinburgh, EH3 9YW Search for other works by this author on: This Site PubMed Google Scholar K. Craig; K. Craig 1Medical Renal Unit and Clinical Pharmacology Unit, Royal Infirmary, Edinburgh, EH3 9YW Search for other works by this author on: This Site PubMed Google Scholar M.R. Lee; M.R. Lee 1Medical Renal Unit and Clinical Pharmacology Unit, Royal Infirmary, Edinburgh, EH3 9YW Search for other works by this author on: This Site PubMed Google Scholar C.P. Swainson C.P. Swainson 1Medical Renal Unit and Clinical Pharmacology Unit, Royal Infirmary, Edinburgh, EH3 9YW Search for other works by this author on: This Site PubMed Google Scholar Clin Sci (Lond) (1991) 80 (s24): 15P. https://doi.org/10.1042/cs080015P Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Facebook Twitter LinkedIn MailTo Cite Icon Cite Get Permissions Citation D.W. Eadington, S. Freestone, K. Craig, M.R. Lee, C.P. Swainson; Effect of Lithium on Systemic and Renal Responses to Angiotensin II Infusion in Normal Man. Clin Sci (Lond) 1 March 1991; 80 (s24): 15P. doi: https://doi.org/10.1042/cs080015P Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsClinical Science Search Advanced Search This content is only available as a PDF. © 1991 The Biochemical Society and the Medical Research Society1991 Article PDF first page preview Close Modal You do not currently have access to this content.

To clarify the contribution made by the renin-angiotensin system activation to the short lived hypotensive response to fenoldopam, the haemodynamic effects of a combination of fenoldopam (100 mg) and enalapril (5 mg) were compared with fenoldopam alone, enalapril alone and placebo in a balanced, randomised, double blind, single dose study in eight hypertensive patients. Fenoldopam caused an acute fall in blood pressure which lasted approximately 3 h after dosing and was associated with a reflex tachycardia. Enalapril caused a more gradual fall in blood pressure (onset 2 h) without a reflex tachycardia. The combination of drugs produced greater reductions in blood pressure sustained for a longer period than fenoldopam alone and with a more rapid onset than enalapril alone. In combination the hypotensive effects of fenoldopam and enalapril were clearly additive and not synergistic. Activation of the renin-angiotensin system does not antagonise significantly the hypotensive effect of fenoldopam.

1. Factors influencing the total body and renal clearances of inulin were investigated in a total of 37 healthy adult volunteers and 10 patients with stable chronic renal failure after the single intravenous injection of a dose of 70 mg/kg given over 5 min. 2. The elimination of inulin was highly concentration-dependent, and in healthy volunteers the renal clearance fell from 103.7 +/- 14.4 ml min-1 1.73 m-2 during the first hour after administration to 49.1 +/- 20.9 ml min-1 1.73 m-2 over the period 6-8 h. In the patients with renal failure the renal clearance fell correspondingly from 39.7 +/- 16.5 to 26.6 +/- 8.6 ml min-1 1.73 m-2. There were no changes in the simultaneously measured clearances of creatinine. 3. The values obtained for the total body clearance of inulin after a single injection depend critically on dose, the number and timing of blood samples, the choice of pharmacokinetic model, the number of data points chosen for estimation of the slope of the terminal elimination phase for analysis by the methods of residuals, and the weighting used for curve fitting by non-linear regression analysis. 4. With standardized conditions of sampling from 0 to 2 h and weighted non-linear regression analysis of the plasma concentration-time data, the total body and renal clearances of inulin were almost identical in subjects with normal renal function at 105.2 +/- 10.2 and 102.9 +/- 13.0 ml min-1 1.73 m-2. In the patients with chronic renal failure sampling was continued for 3 h and the corresponding clearances were 40.4 +/- 15.3 and 38.9 +/- 15.7 ml min-1 1.73 m-2. 5. The 0-2 h total body and renal clearances of inulin were measured by the single injection method and the renal clearance was measured by the standard constant infusion method on different occasions in 10 healthy volunteers. The respective clearances were similar at 101.4 +/- 6.6, 94.9 +/- 11.9 and 88.4 +/- 12.1 ml min-1 1.73 m-2. 6. The reproducibility of the single injection and constant infusion methods was compared by measuring the inulin clearance with both techniques on three occasions in separate groups of eight and nine healthy volunteers. The mean coefficient of variation for the total body clearance with the single injection method was only 3.9% compared with 9.5% for the renal clearance determined the same way and 12.0% for the renal clearance during constant infusion.(ABSTRACT TRUNCATED AT 400 WORDS)

We report mefenamic acid-induced non-oliguric renal failure and severe neutropenia occurring simultaneously in two elderly females. The neutropenia was due to maturation arrest of the myeloid series in one patient. Both patients were also hypothyroid, but it is not clear whether this was a predisposing factor to the development of these adverse reactions. However, it would seem prudent not to use mefenamic acid in hypothyroid patients until the hypothyroidism has been corrected.