Systemic hypertension and hypertensive retinopathy following PPA overdose in a dog.

A 4 yr old spayed female Labrador retriever was examined 4 hr after ingesting an overdose of phenylpropanolamine (PPA). Clinical signs included anxiety, piloerection, mucosal ulceration, cardiac arrhythmia, mydriasis, and hyphema. Clinicopathologic abnormalities included elevated creatine kinase (CK) and aspartate aminotransferase (AST), proteinuria, and pigmenturia. Ventricular tachycardia and severe systemic hypertension were documented. Hyphema and retinal detachment were documented oculus uterque (OU). Phenoxybenzamine, sotalol, and esmolol resolved the ventricular tachycardia, and blood pressure was controlled with nitroprusside. All clinicopathologic and cardiac abnormalities resolved within 7 days, and ocular changes resolved within 1 mo. Monitoring of blood pressure and rapid pharmacologic intervention were successful in controlling hypertension secondary to PPA overdose and minimizing retinal damage.

Evaluation of the effect of tolterodine on pupil diameter and anterior chamber parameters with the Pentacam.

BACKGROUND: To evaluate the effect of tolterodine on pupil diameter and anterior chamber parameters, including volume, depth, and angle, with the Pentacam. METHODS: The 56 eyes of 28 patients who were diagnosed as having overactive bladder and planned to be treated with tolterodine were followed up prospectively in the study. All the patients underwent full ophthalmic examination and scanning with the Pentacam (Oculus, Inc., Wetzlar, Germany) before and 4 weeks after the start date of tolterodine therapy. In addition, the 30 eyes of 15 healthy volunteers were analyzed twice as a control group for repeatability of the measurements. RESULTS: The quantitative descriptors of the anterior chamber before and after the treatment, respectively, were as follows: pupil diameter, 3.02 ± 0.56 mm and 3.01 ± 0.55 mm; anterior chamber depth, 2.74 ± 0.35 mm and 2.75 ± 0.34 mm; anterior chamber volume, 150.23 ± 33.95 mm(3) and 150.27 ± 34.48 mm(3); and anterior chamber angle, 34.56° ± 5.68° and 35.03° ± 5.99°. For all the measurements, the differences did not reach statistical significance (p > .05). Also, the comparison of the same parameters obtained from the first and second measurements of healthy volunteers was not statistically significant (p > .05). CONCLUSION: Our study demonstrates that tolterodine does not affect pupil diameter and anterior chamber parameters, including angle, volume, and depth. Most likely, it is an organ-selective agent, inhibiting muscarinic receptors in the bladder rather than in the anterior segment of the eye.

The relevance of the urinary concentration of ephedrines in anti-doping analysis: determination of pseudoephedrine, cathine, and ephedrine after administration of over-the-counter medicaments.

This article describes a method for the detection and quantitation of cathine, pseudoephedrine, ephedrine, and methylephedrine in urine, using their deuterated analogues as internal standards and derivatization to form the corresponding trimethylsilyl derivatives after a simple liquid-liquid extraction. The study was designed to evaluate whether the urinary cutoff values set by the World Anti-Doping Agency for the banned ephedrines (cathine >5 microg/mL, ephedrine and methylephedrine >10 microg/mL) can be exceeded after the normal self-administration of common over-the-counter medicaments containing nonbanned ephedrines. The present method, after validation, has been applied on real urine samples obtained from 9 healthy volunteers taking different doses of over-the-counter preparations containing ephedrines. Results obtained from excretion studies show high interindividual differences in the urinary concentrations of both pseudoephedrine and cathine, not dependent on body weight or sex nor, in some instances, on the administered dose. The same typical therapeutic dose of pseudoephedrine (60 mg) produced a urinary concentration of more than 5 microg/mL for cathine and of more than 100 microg/mL for pseudoephedrine in 2 of 9 subjects only. When a dose of 120 mg was administered, cathine concentration exceeded 5 microg/mL in 4 of 7 subject, and also concentrations of pseudoephedrine above 100 microg/mL. After administration of 5 x 120 mg of pseudoephedrine (120 mg administered every 7 days for 5 weeks) to one of the subjects exceeding the urinary threshold values, the urinary concentration of cathine and pseudoephedrine exceeded 5 microg/mL (peak concentration 14.8 microg/mL) and 100 microg/mL (peak concentration 275 microg/mL), respectively. When the same subject took 180 mg of pseudoephedrine, the urinary concentration values were below 5 microg/mL for ephedrine and 100 microg/mL for pseudoephedrine. In the case of ephedrine administration in a sustained-release formulation containing 12 mg of ephedrine, 2 of 3 subjects exceeded the urinary cutoff value of 10 microg/mL. The high interindividual variability is still significant even if the urinary concentration values are adjusted by specific gravity and/or creatinine. These results confirm a high interindividual variability in the urinary concentration of ephedrines after the administration of the same therapeutic dose of a preparation.

Tolterodine does not affect memory assessed by passive-avoidance response test in mice.

Antimuscarinics are first-line pharmacotherapy for the treatment of overactive bladder. However, because central nervous system cholinergic neurotransmission is involved in cognition, and the central nervous system-permeable antimuscarinics scopolamine and oxybutynin affect memory, cognitive impairment has been noted as a possible side effect of these drugs. We evaluated the effect of tolterodine, an antimuscarinic for overactive bladder, in a mouse passive-avoidance model of memory. Mice were chosen because like humans, mice but not rats, form the pharmacologically active 5-hydroxymethyl metabolite of tolterodine, DD01. In the passive-avoidance test, tolterodine at 1 or 3 mg/kg had no effect on memory; the latency to cross and percentage of animals crossing were comparable to controls. In contrast, scopolamine induced a memory deficit; the latency to cross was decreased, and the number of animals crossing was increased. Therefore, at a dose exceeding therapeutic exposure by six-fold, tolterodine had no effect on memory in the mouse passive-avoidance model, indicating that tolterodine does not disrupt cognitive function in this testing paradigm.

Transcript of protein kinase A knock-down modulates feeding behavior and neuropeptide Y gene expression in phenylpropanolamine-treated rats.

Neuropeptide Y (NPY) is an appetite-controlling neuromodulator that contributes to the appetite-suppressing effect of phenylpropanolamine (PPA). Aims of this study were to investigate whether protein kinase A (PKA) signaling is involved in regulating NPY gene expression and PPA-induced anorexia. Rats were given daily with PPA for 5 days. Changes in daily food intake and hypothalamic NPY, PKA, cAMP response element binding protein (CREB), and pro-opiomelanocortin (POMC) gene expression were measured and compared. To further determine if PKA was involved, intracerebroventricular infusions of antisense oligodeoxynucleotide were performed at 60 min before daily PPA treatment in freely moving rats. Results showed that daily PKA, CREB, and POMC expression were increased following PPA treatment, which showed a closely reverse relationship with alterations of decreased feeding behaviors and NPY mRNA levels. Results also showed that PKA knock-down could block PPA-induced anorexia as well as restore NPY mRNA level, indicating the involvement of PKA signaling in the regulation of NPY gene expression. It is suggested that hypothalamic PKA signaling may participate in the central regulation of PPA-mediated appetite suppression via the modulation of hypothalamic NPY gene expression. The present findings reveal that manipulations at the molecular level of PKA or cAMP may allow the development of therapeutic agents to improve the undesirable properties of PPA or other amphetamine-like anorectic drugs.

Effect of Catha edulis (khat) on behaviour and its potential to induce seizures in Sprague Dawley rats.

BACKGROUND: Khat is a plant whose young shoots and leaves are habitually used in Eastern Africa and the Arabian Peninsula as a drug of recreation. Although it is used without any control in these regions, it contains two controlled substances, cathinone (schedule I) which is present in fresh khat and cathine (schedule VI) which is a degradation product of cathinone abundant in old khat. OBJECTIVE: To determine the effect of khat on locomotor behaviour and seizures in rats. DESIGN: Experimental study. SETTING: University of Nairobi. SUBJECTS: Adult male rats in groups of six were given fresh khat, old khat, methylphenidate and saline at varying doses and observed over three hours. RESULTS: Fresh khat at low doses and old khat at high doses stimulated locomotor activity. High doses of fresh and old khat induced stereotype behaviour and seizures. CONCLUSION: The results show that khat stimulates locomotor and stereotypic behavioural activity and can induce seizures; results similar to those observed with amphetamine analogs.

Phenylthioalkylamines in experimental tumor treatment in mice.

Two phenylthioalkylamines, phenylthioethylamine (PTEA) and phenylthiopropylamine (PTPA), were prepared and tested for cytotoxicity in vitro and as antitumor agents in (C57BL X DBA/2)F1 (BDF1) mice. Low concentrations of PTEA (median effective concentrations of 8.0, 12.0, and 1.3 micrograms PTEA/ml) inhibited the growth of P388 murine lymphoma, L1210 leukemia, and B16 melanoma cells in culture. PTPA was more effective; concentrations of 0.80, 0.56, and 0.35 micrograms PTPA/ml inhibited the growth of P388, L1210, and B16 in vitro by 50%. PTEA and PTPA treatment increased survival times in BDF1 mice bearing the P388 lymphoma, L1210 leukemia, B16 melanoma, and Lewis lung tumors. Multiple daily administrations of the test compounds were more effective than single daily injections in increasing the life-span in mice bearing the P388 lymphoma and B16 melanoma. Both PTEA and PTPA inhibited the enzyme copper-zinc superoxide dismutase.

Cardiac toxicity from phenylpropanolamine overdose in a dog.

A 5-year-old, 29-kg, female Labrador retriever developed tachypnea, tachycardia, and ataxia following ingestion of approximately 48 mg/kg of phenylpropanolamine. Initial diagnostic tests showed multiform ventricular tachycardia, left ventricular dilatation with a focal dyskinetic region in the dorsal interventricular septum, and elevations in creatinine kinase and cardiac troponin I. All abnormalities resolved within 6 months. The transient electrocardiographic, echocardiographic, and biochemical abnormalities were consistent with myocardial necrosis from infarction or direct catecholamine-induced myocardial toxicity.

High prevalence of potentially hepatotoxic herbal supplement use in patients with fulminant hepatic failure.

HYPOTHESIS: The use of potentially hepatotoxic herbal and dietary supplements is highly prevalent in the fulminant hepatic failure (FHF) patient population at our institution, and this subgroup of patients has a worse prognosis. DESIGN: Retrospective case series. Settings An adult tertiary care university hospital and a Veterans Affairs hospital in Oregon. PATIENTS: All patients referred to the liver transplantation service for FHF from January 2001 through October 2002 (N = 20). We defined FHF as onset of encephalopathy within 8 weeks of onset of jaundice in the absence of preexisting liver disease. All patients underwent investigation for potential causes of liver injury. Potentially hepatotoxic supplements were defined as those with previously published reports of hepatic injury related to their use. RESULTS: Ten patients (50%) were recent or active users of potentially hepatotoxic supplements or herbs; 10 had no history of supplement use. In the supplement group, 7 patients (35%) had no other identified cause for hepatic failure. Six patients in the supplement group and 2 patients in the nonsupplement group underwent orthotopic liver transplantation. Five patients in each group died. There were no significant differences in transplantation rate (P =.07) or survival (P>.99) between groups. Supplement use alone accounted for the most cases of FHF during this period, exceeding acetaminophen toxicity and viral hepatitis. CONCLUSIONS: Herbal and dietary supplements were potential hepatotoxins in a high proportion of patients with FHF at our institution. Enhanced public awareness of the potential hepatotoxicity of these commonly used agents and increased regulatory oversight of their use is strongly urged.

Effects of phenylpropanolamine infusion and withdrawal on body weight and dietary composition in male and female rats.

Male and female rats with ad lib access to separate sources of carbohydrate, fat, and protein were implanted with minipumps providing one of three dosages (0.0, 40.0, or 80.0 mg/kg/day) of phenylpropanolamine (PPA) for 2 weeks. Body weight, macronutrient intake, and water consumption were measured daily before, during, and after PPA treatment. Phenylpropanolamine lowered body weight and caloric intake in males and females, and water consumption in females, but did not alter dietary composition in either sex. After PPA termination, caloric intake returned to control levels in both males and females. However, body weight returned to control levels in males only, while PPA-treated females continued to weigh less than controls. Phenylpropanolamine termination was associated with significant increases in water consumption and the percentage of total calories consumed from protein and reductions in the percentage of calories from carbohydrate in males. In contrast, water and macronutrient consumption was similar comparing PPA-treated females to controls after drug termination. These results suggest there are sex differences in the effects of PPA termination on water and macronutrient consumption that result in differential weight gain in males and females.

Reversal of phenylpropanolamine anorexia in rats by the alpha-1 receptor antagonist benoxathian.

Phenylpropanolamine (PPA) is a phenethylamine anorectic drug that exerts direct agonist effects predominantly on alpha-1 adrenergic receptors, with some alpha-2 adrenergic activity. Direct injections of PPA as well as the alpha-1 agonist 1-phenylephrine into rat paraventricular nucleus (PVN) suppress feeding. In the present study, we evaluate the hypothesis that systemic PPA acts within the PVN on an alpha-1 receptor population to suppress feeding. Accordingly, adult male rats were prepared with a unilateral guide cannula aimed at the PVN. Microinjection of the alpha-1 adrenergic receptor antagonist benoxathian (0, 2.5, 5.0 or 10.0 nmol) into the PVN was found to have no effect on baseline feeding behavior. Microinjection of 10.0 nmol benoxathian into the PVN completely reversed the anorexia induced by 2.5, 5.0 or 10.0 mg/kg PPA (IP), yet did not alter the hypodipsia produced by PPA. These data strongly suggest that PPA anorexia is mediated by an alpha-1 adrenergic satiety mechanism within the PVN.

Assessment of the role of oxytocin receptors in phenylpropanolamine-induced anorexia in rats.

The anorexic effects of phenylpropanolamine (PPA) have been attributed to activation by PPA of alpha 1-adrenoceptors within rat hypothalamic paraventricular nucleus (PVN). The PVN, however, is a nexus for a number of ascending and descending fibers systems that release transmitters and modulators known to inhibit appetite. The focus of the present study was to assess the possibility that oxytocin activity might play a role in the anorexic action of PPA. The present study therefore examined the effects of systemic administration of the oxytocin antagonist L-366,948 on PPA-induced anorexia. Adult male rats (n = 10 per group) were pretreated (i.p.) with either 0, 1, or 2 mg/kg L-366,948 15 min prior to treatment injections (i.p.) of either 0, 5, 10 and 15 mg/kg PPA. Food and water intakes were recorded for a 30 min period (1600 h) starting 30 min after the treatment injection. Rats pretreated with vehicle and then treated with PPA exhibited a dose-dependent suppression of feeding with a maximal effect evident at 15 mg/kg PPA. Pretreatment with 1 or 2 mg/kg L-366,948 alone did not alter feeding nor did these doses alter the anorexia induced by PPA. These results suggest that direct or indirect oxytocin activity is not a factor in the anorexic action of PPA, a finding that further strengthens the notion that PPA inhibits food intake via activation of alpha 1-adrenoceptors.

The identification of neuropeptide Y receptor subtype involved in phenylpropanolamine-induced increase in oxidative stress and appetite suppression.

Hypothalamic neuropeptide Y (NPY) and superoxide dismutase (SOD) have been reported to participate in the regulation of appetite-suppressing effect of phenylpropanolamine (PPA), a sympathomimetic agent. This study explored whether Y1 receptor (Y1R) and/or Y5 receptor (Y5R) was involved in this regulation. Wistar rats were treated with PPA for 24 h. Changes in food intake and hypothalamic NPY, Y1R, Y5R, and SOD contents were assessed and compared. Results showed that food intake and NPY contents were decreased following PPA treatment, while Y1R and SOD contents were increased and Y5R contents remained unchanged. Moreover, although Y1R or Y5R knockdown by themselves could modify the food intake, Y1R but not Y5R knockdown could modify PPA-induced anorexia as well as NPY and SOD contents. In addition, selective inhibition of Y1R but not Y5R could modulate PPA-induced anorexia. It is suggested that Y1R but not Y5R participates in the anorectic response of PPA via the modulation of NPY and SOD. Results provide molecular mechanism of NPY-mediated PPA anorexia and may aid the understanding of the toxicology of PPA.

Preparation, characterization and pharmacological evaluation of tolterodine hydrogels for the treatment of overactive bladder.

In this study, transdermal gel formulations for tolterodine were developed to investigate the effects of gel matrix and chemical enhancers on drug skin permeation from tolterodine hydrogels. In vitro permeation studies of tolterodine through excised mouse skin were carried out using Franz-type diffusion cells. In the optimum gel formulation, Carbopol 940 was selected as the gel matrix. Compared to gels without enhancer, tolterodine hydrogels with N-methyl pyrrolidone (NMP) showed significant enhancing effect on transdermal permeation of tolterodine (p<0.05). The results of in vitro percutaneous delivery experiment showed that the relationship of the steady accumulative percutaneous amount (Q, µg cm(-2)) of tolterodine hydrogels and time was Q4-12h=770.19t(1/2)-966.99. Tolterodine permeated at the steady-state speed of 770.19 µg cm(-2)h(-1) and its release coincided with Higuchi Equation. The pharmacokinetic properties of the optimized tolterodine formulation were studied in rabbits. The absolute bioavailability of tolterodine was 11.47%. Since the absence of hepatic first-pass metabolism, only a single active compound-tolterodine was detected in the plasma. A skin irritation study was also carried out on rabbits, and the results showed tolterodine hydrogels had no skin irritation. In the pharmacodynamic study, the significant effects of tolterodine hydrogels on the inhibition of pilocarpine-induced rat urinary bladder contraction were last to 12h, indicating that tolterodine hydrogels could produce prolonged pharmacological responses. In conclusion, tolterodine hydrogels were formulated successfully using Carbopol 940 and NMP and these results helped in finding the optimum formulation for percutaneous drug release. It is quite evident that tolterodine hydrogels may offer a possibility to avoid the first-pass effect, resulting in a single active compound of tolterodine in plasma, which may profit on the patient under the dose control and the reduction of potential adverse effect from two active compounds in the body.

Myocardial necrosis due to intraperitoneal administration of phenylpropanolamine in rats.

Overdose with the sympathomimetic agent phenylpropanolamine (PPA) may cause arrhythmias and myocardial injury in humans. To study the mechanism of these toxic effects, unanesthetized rats (6 animals per group) were given single intraperitoneal doses of 1, 2, 4, 8, 16, or 32 mg/kg PPA. Increases in blood pressure, measured by tail cuff, were dose related and comparable to increases reported in patients with PPA toxicity. Animals were killed at 24 hr and light microscopic examination showed diffuse, dose-related myocardial necrosis. Histology scores (a measure of severity of necrosis) in groups receiving 8, 16, and 32 mg/kg PPA were 1.4 +/- 0.5, 1.8 +/- 1.0, and 2.3 +/- 0.4, respectively, and were all significantly greater than the histology score of control animals (0.2 +/- 0.3, p less than 0.01). The observed lesion was similar in appearance to the myocardial necrosis produced by large doses of catecholamines or sympathomimetic agents in rats. In summary, single doses of PPA caused myocardial necrosis in rats at doses comparable to those causing toxicity in humans. Myocardial necrosis may contribute to the cardiac toxicity of PPA overdose.

Chromosomal and biochemical studies on the effect of kat extract on laboratory rats.

Kat is being used extensively in many countries as a central nervous system stimulant. The effect of three doses of crude kat extract on chromosomal division and abnormalities in bone marrow, as well as on DNA, RNA, and total protein content in brain and liver was studied in laboratory rats in order to test the possible mutagenicity of the drug. Kat was given as a single subcutaneous injection at 0.05 (usage dose), 0.52 (intermediate dose), and 1.00 (sublethal dose) g/kg body weight. Animals were sacrificed at 6, 24, and 48 hr after treatment. Also, some animals were exposed subacutely for 5 consecutive days with sacrifice occurring 6 hr after the last injection. The mitotic index was reduced by all treatments, with the greatest effect occurring in the subacute treatment. Chromosomal abnormalities were induced by kat at all three doses, administered acutely or subacutely. The significant chromosomal aberrations were in the form of gaps, breaks, centromeric attenuations, and centric fusions. The concentration of DNA, RNA, and total protein in liver and brain decreased at all doses, with the greatest decrease occurring after subacute treatment. These findings suggest that kat has a profound effect on cell proliferation, on chromosomal abnormalities, and on DNA, RNA, and total protein synthesis.