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Microbial transformation of the antihistaminic drug triprolidine hydrochloride.

The production of a known mammalian metabolite of the antihistamine triprolidine through fungal metabolic transformation has been demonstrated. The filamentous fungus Cunninghamella elegans ATCC 9245 was grown in Sabouraud dextrose broth containing triprolidine hydrochloride monohydrate. One major metabolite was extracted with methylene chloride, isolated by high-performance liquid chromatography, and identified by its proton-nuclear magnetic resonance and desorption chemical ionization mass spectral properties as hydroxymethyl triprolidine (2-[1-(4-hydroxymethylphenyl)-3-(1-pyrrolidinyl-1-propenyl)] pyridine). After 240 h of incubation, the hydroxymethyl derivative represented approximately 55.0% of the initial dose. Fungal oxidation of hydroxymethyl triprolidine to the corresponding carboxylic acid triprolidine derivative (also a known mammalian triprolidine metabolite) was not observed. No mutagenic activity was observed for triprolidine and hydroxymethyl triprolidine by reversion of Salmonella typhimurium strains TA97, TA98, TA100, and TA104 at concentrations up to 1000 and 200 micrograms/plate, respectively. These results suggest that the fungal metabolism of triprolidine to the hydroxymethyl derivative occurs predominantly through pathways which do not result in mutagenic activation. Incubation of C. elegans with triprolidine under an 18O2 atmosphere and subsequent electron impact mass spectral analysis of the hydroxymethyl triprolidine formed indicate that molecular oxygen was incorporated into the methyl group and suggest a mono-oxygenase catalyzed reaction. This study parallels previous studies on the mammalian metabolism of triprolidine and clearly indicates that the microbial transformation of triprolidine is a useful alternative for the synthesis of potential mammalian metabolites.

Animals↗

Enhanced efficacy of triprolidine by transdermal application of the EVA matrix system in rabbits and rats.

The bioavailability of triprolidine from the ethylene vinyl acetate (EVA) matrix system containing polyoxyethylene-2-oleyl ether was studied to determine the feasibility of enhanced transdermal delivery of triprolidine in rabbits. The antihistamine effects were also confirmed to determine the percutaneous absorption of triprolidine from the EVA matrix system containing a penetration enhancer and plasticizer in rats. The triprolidine-EVA matrix (50mg/kg) was applied to the abdominal skin of rabbits. Blood samples were collected via the femoral artery for 36 h and the plasma concentrations of triprolidine were determined by HPLC. The pharmacokinetic parameters were calculated using the LAGRAN computer program. The area under the curve(AUC) was significantly higher in the enhancer group (4582+/-1456 ng/mL h) than that (2958+/-997 ng/mL h) in the control group (P<0.05), showing an approximate 155% increased bioavailability. The average Cmax in the enhancer group (241+/-46.5 ng/mL) was significantly higher than that in the control group (198+/-28.9 ng/mL), (P<0.05). The mean Tmax in the enhancer group (8.0+/-2.57 h) was higher than that in the control group (6.0+/-2.24 h, but this was not statistically significantly. The relative bioavailability of triprolidine in the transdermal application was 35.9% in the control group and 55.6% in the enhancer group compared comparing with that after oral administration. As the triprolidine-EVA matrix, which contains polyoxyethylene-2-oleyl ether as an enhancer and triethyl citrate as a plasticizer was administered to the rabbits via the transdermal routes, the relative bioavailability increased approximately 1.55 fold compared with that in the control group, showing a relatively constant, sustained blood concentration with minimal fluctuation. The antihistamine effect was determined using the Evans blue dye procedure by comparing the changes in the vascular permeability increase following the transdermal application. The vascular permeability increase was reduced significantly by the transdermal application of the EVA-triprolidine system containing triethyl citrate and polyoxyethylene-2-oleyl ether. These results show that the plasticizer and penetration enhancer increase the skin permeation of triprolidine and the triprolidine-EVA matrix system could be developed as a transdermal delivery system providing the increased constant plasma concentration and antihistamine effects.

Administration, Cutaneous↗

Triprolidine radioimmunoassay: disposition in animals and humans.

A hapten derivative of triprolidine, bearing an acrylic acid side chain ortho to the pyridine ring nitrogen atom, was synthesized and coupled to bovine serum albumin. Immunization of New Zealand White rabbits with the resulting drug-protein conjugate resulted in the production of antisera capable of binding a radioiodinated tyramine conjugate of the triprolidine hapten derivative at high antiserum dilutions (1:70,000-1:150,000). These antisera were used to develop a radioimmunoassay (RIA) for triprolidine in human plasma with a sensitivity limit of 0.1 ng/mL (0.01 ng of actual mass). The known hydroxymethyl and carboxyl metabolites of triprolidine cross-reacted weakly (less than 2 and less than 0.05%, respectively) with this antiserum. The RIA could be used for the direct analysis of triprolidine in human and rabbit plasma, but not for rat or dog plasma, presumably due to the presence of other interfering substances (possibly metabolites). The validity of the RIA procedure in human plasma was demonstrated by comparative analysis of a number of samples by quantitative TLC (r = 0.985, slope = 1.076). The assay was employed to describe the pharmacokinetics of triprolidine in the rabbit (t 1/2, beta = 1.7 h). The assay had adequate sensitivity to detect low circulating drug concentrations in humans after therapeutic oral doses and also substantiated previous disposition experiments with triprolidine in humans (t 1/2, beta = 2.27 h). TLC analysis demonstrated that the absolute oral bioavailability of triprolidine (1-mg/kg dose) in the dog was low (4%). A comparison of triprolidine pharmacokinetic parameters in dogs, rabbits, rats, and humans revealed considerable similarity in elimination characteristics in these species.

Animals↗

Disposition of triprolidine in the male beagle dog.

Three male beagle dogs were given 2.5 mg/kg doses of [14C]triprolidine HCl monohydrate (2.09 mg/kg of the free base) by intravenous and oral routes, in a nonrandomized cross-over experiment. After either route of administration, approximately 75% of the dose was excreted in the urine, and the remainder was excreted in the feces. Triprolidine was extensively metabolized, with less than 1% of the parent drug recovered in the excreta after either route of administration. Three metabolites were isolated from excreta and identified, including the major metabolite (metabolite 1, 219C69), in which the toluene ring methyl group was oxidized to a carboxylic acid, a metabolite (metabolite 2) in which the pyrrolidine ring was opened with oxidation of the terminal carbon to a carboxylic acid (a gamma-aminobutyric acid), and a metabolite (metabolite 3) that was a pyrrolidinone derivative of 219C69. Other metabolites in urine and feces were present in amounts too small for quantitation or identification. Route of administration had little effect on the metabolic pattern of triprolidine. Thus, after oral administration of triprolidine, a mean of 49.1% of the dose was excreted as 219C69, 12.0% as metabolite 2, 3.4% as metabolite 3, and 0.6% as triprolidine, while after intravenous administration, a mean of 50.8% of the dose was excreted as 219C69, 11.1% as metabolite 2, 4.2% as metabolite 3, and 0.8% as triprolidine. Plasma contained triprolidine, 219C69, and metabolite 2, as well as other apparent metabolites that were present at levels too low for quantitation. Mean pharmacokinetic parameters calculated for triprolidine after intravenous dosing were: CL = 24.4 ml/min/kg, Vdss = 5.8 liters/kg, and Vc = 1.6 liters/kg.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

An investigation of the H1-receptor antagonist triprolidine: pharmacokinetics and antihistaminic effects.

A single oral dose of triprolidine hydrochloride, 0.04 mg/kg (mean dose 2.7 +/- SD 0.4 mg) was administered to seven healthy, fasting adult volunteers who had never been treated previously with H1-receptor antagonists. Blood sampling and intradermal tests with 0.01 ml of histamine phosphate (0.1 mg/ml) were performed at -0.25, 1, 2, 3, 4, 5, 6, 7, 8, and 12 hours after the dose. Wheal-and-flare circumferences were traced, and the areas were measured by planimetry. Pruritus was quantitated by use of a clinical score. Urine was collected in 6-hour pooled aliquots for a total of 24 hours. Serum and urine triprolidine concentrations were measured by high-performance liquid chromatography. Wheal-and-flare areas and pruritus decreased after the triprolidine dose. Suppression of mean flare size was statistically significant at 2, 3, 6 and 8 hours. Suppression of mean wheal size was not statistically significant at any time compared to predose values. The mean triprolidine serum half-life was 2.1 +/- 0.8 hours. The mean peak serum triprolidine concentration of 15.4 +/- 8.3 ng/ml occurred 2 hours after ingestion. No triprolidine was detected in the serum after 12 hours. The mean urinary excretion of unchanged triprolidine during 24 hours was 1.3 +/- 1.0% of the dose administered.

Adult↗

The effects of single and repeated administration of ebastine on cognition and psychomotor performance in comparison to triprolidine and placebo in healthy volunteers.

OBJECTIVE: The cognitive and psychomotor effects of 10 mg, 20 mg and 30 mg ebastine, a second generation H1-receptor antagonist, were compared with sustained release triprolidine 10 mg (as a verum) and placebo in 10 healthy volunteers in a double-blind, randomised cross-over study. METHODS: Following each dose, subjects were required to perform a series of tests of cognitive function and psychomotor performance at 1 h, 2 h, 4 h and 8 h post-dose on days 1 and 5. The test battery consisted of critical flicker fusion, choice reaction time, simulated car tracking task, Sternberg memory scanning task, assessment of subjective sedation (LARS) and subjective evaluation of sleep (LSEQ). RESULTS: Ebastine at all doses investigated was not statistically significant from placebo in any of the objective tests used. However, as expected for a positive internal control, a number of objective measures were significantly disrupted by triprolidine (p < 0.05). Triprolidine produced an overall increase of the peripheral reaction time component of the simulated car tracking task (SCTT), the difference with placebo reaching statistical significance on day 1, 8 h post-dose (p < 0.05). The mean tracking accuracy scores were also significantly impaired following the administration of triprolidine after 8h on day 1 (p < 0.05). Triprolidine also produced a clear decrement on the SMST (Sternberg Memory Scanning Task), which was significantly different from placebo, at 4 h and 8 h post-dose on day 1. Subjective reports of sedation (LARS) were significantly greater at 2 h and 4 h following triprolidine administration on day 1 and ebastine (30 mg) was rated as sedative 4 h following administration on day 5. The perceived sedative activity of ebastine 30 mg was also reflected in the subjective reports on the LSEQ on day 1 (p < 0.05). CONCLUSIONS: These results allow the conclusion that ebastine, at its recommended therapeutic doses of 10-20 mg, is demonstrably free from impairment on objective aspects of psychomotor and cognitive function in a study where the psychometric assessments were shown to be sensitive to disruptive effects, as evidenced by the action of the positive control, triprolidine 10 mg.

Adult↗

Enhanced bioavailability of triprolidine from the transdermal TPX matrix system in rabbits.

The pharmacokinetics and bioavailability of triprolidine, antihistamines, were studied to determine the feasibility of enhanced transdemal delivery of triprolidine from the poly(4-methyl-1-pentene) (TPX) matrix system containing polyoxyethylene-2-oleyl ether in rabbits. The triprolidine-TPX matrix (50 mg/kg) was applied to abdominal skin of rabbits. Blood samples were collected via femoral artery for 36 h and the plasma concentrations of triprolidine were determined by HPLC. Pharmacokinetic parameters was calculated using the LAGRAN computer program. The area under the curve (AUC) was significantly higher in the enhancer group (4058 +/- 1420 ng/ml h) than that (1902 +/- 857 ng/ml h) in control group (P<0.05), showing about 235% increased bioavailability. The average Cmax was increased significantly in the enhancer group (216 +/- 44.3 ng/ml) compared with control group (130 +/- 25.8 ng/ml) (P<0.05). The mean Tmax was increased in the enhancer group (8.0 +/- 2.55 h) compared with the control (6.0 +/- 2.28 h) but was not significant. The relative bioavailability was 23.1% in the control group and 49.3% in the enhancer group compared to the oral route. As the triprolidine-TPX matrix containing polyoxyethylene-2-oleyl ether as an enhancer and tiethyl citrate as a plasticizer was administered to rabbits via the transdermal routes, the relative bioavailability increased by about 2.13-fold compared to the control group, showing a relatively constant, sustained blood concentration with minimal fluctuation. The results of this study shows that triprolidine-TPX matrix could be developed as a transdermal delivery system providing consistent plasma concentration.

Administration, Cutaneous↗

Kinetic spectrophotometric methods for the quantitation of triprolidine in bulk and in drug formulations.

A kinetic method for the accurate and sensitive determination of triprolidine has been described. The method is based on the alkaline oxidation of triprolidine with KMnO(4). At a fixed time of 20 min, the formed manganate ion is spectrophotometrically measured at 612 nm. The concentration of triprolidine is calculated using the calibration equation for the fixed time method. Beer's law was obeyed from 6 to 40 microg ml(-1) and the R.S.D. (n=10) was 0.97%. Recovery was 99.80%. The method is suitable for quantitative determination of triprolidine in the presence of co-formulated drugs, since pseudoephedrine hydrochloride, which is frequently co-formulated with triprolidine did not interfere with this assay. The intra- and inter-day R.S.D. values indicated the ruggedness of the method. The method has been applied successfully to commercial tablet dosage form. The results obtained agreed with those obtained by the BP method. The determination of triprolidine by the fixed-concentration and rate constant methods is feasible with the calibration equations obtained, but the fixed time method proves to be more applicable.

Anti-Allergic Agents↗

The acute effects of acrivastine (BW825C), a new antihistamine, compared with triprolidine on measures of central nervous system performance and subjective effects.

The new H1-antagonist acrivastine (BW825C) in doses of 4, 8, and 16 mg was compared with triprolidine HCl (2.5 and 5 mg) in a double-blind crossover study in 12 subjects. Adaptive tracking performance 1.5 hours after dosing was impaired by triprolidine, 2.5 and 5 mg; the impairment was still detectable 3.5 hours after 5 mg. Acrivastine did not impair adaptive tracking after any of the doses. Triprolidine increased reaction times after 1.5 hours (2.5 and 5 mg) and 3 hours (5 mg), but acrivastine did not have any effect on reaction time at any dose. Both doses of triprolidine caused subjective central nervous system effects after 1.5 hours, and triprolidine, 5 mg, still had some detectable effects on subjective rating scales after 3 hours. No subjective effects were noted after acrivastine. We conclude that acrivastine at doses causing more peripheral H1-antagonism than triprolidine has considerably reduced central nervous system activity.

Administration, Oral↗

A comparison of triprolidine and cyclizine on histamine (H1) antagonism, subjective effects and performance tests in man.

1 The effects of triprolidine and cyclizine on the histamine skin response, performance tests and subjective effects were examined in a controlled, double-blind study in eight healthy volunteers. 2 Triprolidine was considerably more potent that cyclizine in inhibiting the skin response to histamine. Significant inhibition of flare size occurred at 1, 2 an 4 h after triprolidine 2.5 mg. A smaller but significant reduction occurred at 2 and 4 h after cyclizine 100 mg but not after the 50 mg dose. 3 Cyclizine 100 mg produced a significant increase in reaction time at 4.5 h compared with lactose. Smaller though non significant increases followed triprolidine and cyclizine 50 mg. 4 Subjective effects were seen only after cyclizine 100 mg when subjects were significantly more drowsy, feeble, muzzy, lethargic and dreamy than after lactose dummy. No significant changes followed triprolidine 2.5 mg or cyclizine 50 mg. 5 It was concluded that while cyclizine has antihistamine properties, these are weak compared with triprolidine, and are not seen with doses sufficiently low to avoid central nervous system impairment.

Adult↗

Disposition and metabolism of triprolidine in mice.

The disposition of the antihistamine, triprolidine, was studied in male and female CD-1 mice after a single oral 50 mg/kg dose of [14C]triprolidine HCl. Urine and feces collected over 72 hr postdosing were analyzed for total radiocarbon, and for parent drug and metabolites by radiochromatography. Structures of metabolites were determined by GC/MS, direct probe MS, FAB/MS, LC/MS, NMR, and IR techniques. More than 80% of the dose was recovered in the urine, with the remainder recovered in the feces. The carboxylic acid analog of triprolidine (219C69) was found to be the major metabolite in urine and feces, accounting for an average of 57.6% of the administered dose. Three minor metabolites were identified as a gamma-aminobutyric acid analog of triprolidine, a pyrrolidinone analog of 219C69, and a pyridine-ring hydroxylated derivative of triprolidine. Parent drug could only be detected in urine and accounted for 0.3% (females) to 1.1% (males) of the dose. The results of this study showed that triprolidine was absorbed well but extensively metabolized when administered orally to mice.

Animals↗

Determination of triprolidine in human plasma by quantitative TLC.

A chromatographic thin-layer fluorescence procedure, with a sensitivity limit of 0.8 ng/ml, is described for the quantitative analysis of triprolidine in human and rat plasma. Following the intravenous administration of 1 mg/kg of triprolidine to rats, the drug distributed rapidly into tissues and was eliminated from plasma with a half-life of 53 min. The method was used to determine the plasma triprolidine levels in 16 normal human volunteers following oral administration of 3.75 mg of triprolidine hydrochloride in 15 ml of a syrup. The drug obtained a mean peak plasma level of 8.2 ng/ml in 2 hr and was eliminated from the plasma with a half-life of 5 hr. Considerable individual variation was observed in the area under the plasma triprolidine level-time curve; values ranged from 19 to 163 ng hr/ml with a mean value of 75 ng hr/ml.

Administration, Oral↗

A comparison of triprolidine and clemastine on histamine antagonism and performance tests in man: implications for the mechanism of drug induced drowsiness.

The effects of triprolidine hydrochloride 1.25, 2.5 and 5 mg, clemastine 1 and 2 mg and lactose dummy administered orally, in a balanced order, at weekly intervals to 12 healthy volunteers, on the flare and weal responses to intradermal histamine injection, and also on both subjective effects and objective psychomotor tests were examined. The histamine response was significantly larger at 09.00 h falling through the day but increasing by late afternoon. Triprolidine produced a dose-related antagonism of both flare and weal response maximal at 3 h and wearing off after the lower doses at 8 h. Clemastine by contrast produced poor antagonism of histamine at 3 h but a marked effect at 5.5 and 8 h. Auditory vigilance was significantly (p less than 0.05) impaired by all doses of triprolidine 1 to 2 h after administration, but no change followed clemastine at this time. When tested 6 to 7 h after administration significant impairment followed both doses of clemastine but only the 5 mg dose of triprolidine. Both drugs prolonged reaction time in a dose-related manner at 2.5 and 5.0 h but the effects had worn off at 7 h. Digit symbol substitution was impaired by the top doses of both antihistamines but short term memory was unaffected. Subjective effects measured using analogue lines reflected the effects in the vigilance test, in that drowsiness and mental impairment were noted early after triprolidine, while clemastine produced maximal effects at 5 h. Subjects were ranked in order of magnitude of inhibition of both flare and weal, and impairment of vigilance, prolongation of reaction time and subjective drowsiness score. There was no indication of a significant correlation, using Spearman's test, between antagonism of histamine and effects on the central nervous system.

Adult↗

Transport of hydroxyzine and triprolidine across bovine olfactory mucosa: role of passive diffusion in the direct nose-to-brain uptake of small molecules.

Hydroxyzine and triprolidine have both been reported to reach the CNS following nasal administration. The objective of this study was to investigate their in vitro permeation across bovine olfactory mucosa in order to further characterize the biological and physicochemical parameters that influence direct nose-to-brain transport. In vitro experiments were conducted using Sweetana-Grass (Navicyte) vertical diffusion cells to evaluate the effect of directionality, donor concentration and pH on the permeation of hydroxyzine and triprolidine across excised bovine olfactory mucosa. These studies demonstrated that the Jm-s (mucosal-submucosal flux) and Js-m (submucosal-mucosal flux) of hydroxyzine and triprolidine across the olfactory mucosa were linearly dependent upon the donor concentration without any evidence of saturable transport. Hydroxyzine inhibited the efflux of P-gp substrates like etoposide and chlorpheniramine across the olfactory mucosa. Both hydroxyzine and triprolidine reduced the net flux (Js-m-Jm-s) of etoposide with IC50 values of 39.2 and 130.6 microM, respectively. The lipophilicty of these compounds, coupled with their ability to inhibit P-gp, enable them to freely permeate across the olfactory mucosa. Despite the presence of a number of protective barriers such as efflux transporters and metabolizing enzymes in the olfactory system, lipophilic compounds such as hydroxyzine and triprolidine can access the CNS primarily by passive diffusion when administered via the nasal cavity.

Animals↗

Enhanced transdermal delivery of triprolidine from the ethylene-vinyl acetate matrix.

Triprolidine-containing matrix was fabricated with ethylene-vinyl acetate (EVA) copolymer to control the release of the drug. The permeation rate of triprolidine in the stripped skin was greatly larger than that in the whole skin. Thus it showed that the stratum corneum acts as a barrier of skin permeation. The effect of penetration enhancer and stripping of skin on the permeation of triprolidine through the excised mouse skin was studied. Penetrating enhancers showed increased flux probably due to the enhancing effect on the skin barrier, the stratum corneum. Among enhancers used such as glycols, fatty acids and non-ionic surfactants, polyoxyethylene-2-oleyl ether showed the best enhancement. The permeability of triprolidine was markedly increased with stripping of the mouse skin to remove the stratum corneum that acts as a barrier of skin permeation. For the controlling transdermal delivery of triprolidine, the application of EVA membrane containing permeation enhancer could be useful in the development of transdermal drug delivery system.

Administration, Cutaneous↗

Effects of triprolidine and dipipanone in the cold induced pain test, and the central nervous system of healthy volunteers.

1 Twelve healthy volunteers took part in a study of the interaction between the antihistamine triprolidine and the opioid dipipanone in the cold induced pain (CP) test and tests of sedation. They received placebo, triprolidine 2.5 mg, dipipanone 8 mg or the combination of the two active treatments according to a double-blind, randomised, balanced, crossover design. 2 Antihistamine activity was demonstrated by triprolidine reducing the size of wheals and flares produced by intradermal histamine 1.6 micrograms. However, triprolidine produced no analgesia in the CP test, nor did it enhance the analgesia produced by dipipanone alone. 3 Neither treatment alone produced statistically significant sedation, assessed by visual analogue scales (VAS), side effect check list, body sway and reaction times. However, the combination did cause significant sedation. 4 Dipipanone reduced pupil size, depressed respiration, and decreased salivation. Triprolidine had no effects on pupil size and respiration, but reduced salivation slightly. It was concluded that histaminergic (H1) mechanisms are unlikely to be involved in pain produced by cold.

Adult↗

Bioavailability of pseudoephedrine and triprolidine from combination and single-ingredient products.

The bioavailability of pseudoephedrine and triprolidine from combination and single-ingredient products was evaluated in a randomized, four-way crossover study. Healthy men volunteers received single doses of a tablet containing triprolidine hydrochloride and pseudoephedrine hydrochloride, a syrup containing the same two drugs, and single-ingredient tablets of each drug. Blood samples were collected before each dose and at 13 sampling times over 24 hours for determination of drug concentrations by radioimmunoassay. Observed peak concentration (Cmax), corresponding observed peak time (tmax), area under the plasma drug concentration-time curve from dosing to time infinity (AUC), and the ratio between plasma clearance and extent of bioavailability (CL/F) were determined. Nonlinear regression analysis was used to obtain estimates of lag time for absorption, first-order rate constant for absorption, first-order rate constant for elimination, and ratio between volume of distribution and extent of bioavailability. Data were analyzed for 19 of 20 men entering the study; data were complete for 16 of these. Pseudoephedrine concentrations were significantly different for the combination tablet and the syrup at four sampling times; no significant differences were found between pseudoephedrine concentrations for the combination tablet and single-ingredient tablet. Cmax, tmax, AUC, and CL/F for pseudoephedrine were not significantly different for the three formulations. Triprolidine concentrations at 8 hours were significantly higher for the combination tablet than for the single-ingredient tablet, and tmax for triprolidine was significantly higher for the combination tablet than for the syrup. For both pseudoephedrine and triprolidine, the combination tablet was bioequivalent to the syrup and to the single-drug tablets.

Adolescent↗

Triprolidine: 104-week feeding study in rats.

The antihistamine triprolidine hydrochloride, was fed at dietary concentrations of 0, 250, 1000, or 2000 ppm (as the free base) to groups of 60 Fischer 344 (F344) rats of each sex for up to 2 years to evaluate its potential carcinogenicity. Up to 12 per sex from each group were killed at 65 weeks, and hematology, clinical chemistry, and histopathology were evaluated. A complete histopathological evaluation was performed on all other animals; survivors were killed at 2 years. Survival was significantly extended in triprolidine-treated males and females, particularly at the high dose. At the close of the study high-dose males and females had gained significantly less body weight than controls. Among rats killed at 65 weeks females in the mid- and high-dose groups weighed significantly less than controls, but weights of control and dosed males were not significantly different. The incidences of numerous lesions tended to decrease with increasing triprolidine dose. In females, clitoral gland adenomas, thyroid c-cell hyperplasia and neoplasia, mammary gland hyperplasia and fibroadenomas, and uterine stromal polyps, and in males, anterior pituitary gland adenomas, preputial gland neoplasia, thyroid c-cell pancreatic islet neoplasia, mononuclear cell leukemia, and the combination of lymphocytic, histiocytic, and undifferentiated cell malignant lymphomas and mononuclear leukemia, all exhibited negative dose trends. Cytoplasmic alterations of the parotid gland and numerous liver lesions tended to be more frequent in treated than in control animals. Liver lesions that exhibited positive dose trends include chronic inflammation and centrilobular fatty change in both sexes, mixed cell foci, and the combination of mixed cell foci and eosinophilic foci in females, and in males, basophilic foci and eosinophilic foci. Triprolidine was not carcinogenic in F344 rats.

Animals↗