Possible interaction between fluoxetine and pimozide causing sinus bradycardia

Fluoxetine has been reported to have interactions with antipsychotics and other antidepressants with symptoms of toxicity of these drugs. We report a case of a possible interaction with pimozide which led to a potentially life threatening bradycardia. Careful monitoring should be done when these two drugs are prescribed at the same time, especially in the elderly and in patients with cardiac disease.

Pre-natal benzodiazepine exposure. III. Lorazepam exposure is associated with a shift toward inverse agonist efficacy

Pre-natal exposure to benzodiazepines has been associated with neurobehavioral alterations in human and animal studies. To evaluate effects of pre-natal exposure on subsequent efficacy of benzodiazepine ligands, we exposed mice to lorazepam, 2 mg/kg/day, during days 14-20 of gestation and evaluated offspring at 6 weeks of age using pentylenetetrazol-induced convulsions. Mice exposed to lorazepam were similar to vehicle-exposed and untreated mice in pentylenetetrazol threshold. However, lorazepam-exposed mice had a reduced threshold after an acute dose of lorazepam compared to vehicle-exposed and untreated mice. For the proconvulsant inverse agonist compound FG 7142, threshold was also reduced after pre-natal lorazepam exposure compared to the other treatment groups. These data indicate that pre-natal lorazepam exposure is associated in mature mice with a shift in benzodiazepine efficacy toward the inverse agonist range of the benzodiazepine spectrum.

Electroconvulsive shock alters GABAA receptor subunit mRNAs: use of quantitative PCR methodology

Electroconvulsive shock (ECS) may affect several neurotransmitter systems in brain, including the GABAergic inhibitory system. We used a quantitative PCR-based assay to evaluate mRNAs for five GABAa receptor subunits at 2 to 24 h after ECS. mRNAs for the alpha 1 and beta 2 subunits were significantly increased in cerebellum at 4 and 8 h after ECS, and returned to control levels at 24 h. No changes were observed in alpha 2, beta 3, gamma 1, or gamma 2 subunits, and no changes in any subunit evaluated were observed in cortex or hippocampus. These data corroborate prior results obtained for the alpha 1 subunit using Northern hybridization, and illustrate the utility of the PCR assay in quantitating low-abundance mRNAs.

Physician awareness of prescription drug costs: a missing element of drug advertising and promotion

BACKGROUND

Although the cost of prescription drugs is recognized as an important facet of health care expenditures, many physicians are purportedly unaware of actual drug costs. To test this hypothesis, we surveyed physician awareness of the cost of 20 actively marketed prescription drugs.

METHODS

A questionnaire listing four possible cost categories for each drug was administered to 305 registrants of a 5-day family medicine continuing education course.

RESULTS

Ninety-two physicians completed the questionnaire. Only one, a 40-year-old, board-certified physician who had been in practice for 3 years, answered 70% of questions correctly. The average score for the other participants was 37% (range 0% to 75%).

CONCLUSIONS

The majority of physicians questioned could not accurately identify the price range of commonly prescribed drugs. We recommend drug cost disclosure in drug advertising to help address this problem.

Chronic benzodiazepine administration. XII. Anticonvulsant cross-tolerance but distinct neurochemical effects of alprazolam and lorazepam

Tolerance to the sedative and anticonvulsant effects of benzodiazepines has been reported, but cross-tolerance among benzodiazepines is poorly characterized. To evaluate cross-tolerance between lorazepam and alprazolam in a reliable anticonvulsant pharmacodynamic model, we treated mice with either drug for 14 days, and with the two drugs sequentially for 7 days each. Pentylenetetrazole-induced seizure thresholds were similar in mice treated for 14 days with lorazepam or alprazolam, 2 mg/kg/day. For both compounds, a discontinuation effect characterized by reduced seizure threshold occurred at 4 days after discontinuation. Substitution of alprazolam for lorazepam after 1 week, and vice versa, did not interrupt tolerance. [3H]flumazenil binding in vivo was downregulated in cortex after 14 days of either drug. However, binding was also reduced in hippocampus for lorazepam but not for alprazolam. Substitution of alprazolam for lorazepam resulted in downregulation in cortex only, similar to lorazepam alone. Conversely, substitution of lorazepam for alprazolam led to binding changes similar to lorazepam alone. These data demonstrate cross-tolerance to the convulsant effects of pentylenetetrazole between lorazepam and alprazolam. However, effects of the two compounds on benzodiazepine receptor binding in hippocampus remain distinct.

Improving prescription documentation in the ambulatory setting

Use of a standard prescription pad, although it adequately meets the needs of drug delivery, requires the physician to document prescribed medications separately in the medical record. Failure to do so may lead to under-recognition of problems of potential drug interactions and adverse drug reactions, delays in prescription refills, and other areas of quality of care, especially in a setting where multiple physicians may be involved in the care of a patient. Of 83 prescriptions written in a primary care clinic, only 11 (13%) were noted on the chart medication form when physicians used prescription pads. Implementation of a "one-write" noncarbon prescription form that generated an instant copy increased prescription documentation to 83% (49 of 59 prescriptions) (x2 = 68.86; p < 0.005) over a one-week period. In a follow-up study conducted approximately 3.5 years after the initial intervention, use of the "one-write" form had maintained at 82% prescription documentation (32 of 39) prescriptions) (x2 = 52.05; p < 0.005). A "one-write" copy system could improve clinical care by improving medication documentation in the medical record.

Dicyclomine for medical management of persistent anal fissure with associated spasm of the internal sphincter

The case of a 43-year-old woman with persistent anal fissure responsive to dicyclomine is described. Associated spasm of the internal sphincter had precluded fissure healing. The spasm of the internal sphincter relaxed within 24 hours of dicyclomine administration and subsequently allowed healing. Surgery was avoided.

Benzodiazepine receptor binding of benzodiazepine hypnotics: Receptor and ligand specificity

Benzodiazepine (BDZ) hypnotics bind at a specific receptor located on postsynaptic neurons. Some data support specificity of binding for several hypnotics to receptor subtypes. We evaluated BDZ receptor binding in cerebral cortical membranes using agonist, antagonist, and subtype-specific ligands for commonly used hypnotics and their metabolites. All hypnotics competed similarly at BDZ1 and BDZ2 receptor subtypes except quazepam and its metabolite 2-oxo-quazepam and to a lesser extent hydroxyethyl flurazepam (EtOH) flurazepam. These compounds had relative specificity for the BDZ1 site. Triazolam, estazolam, and flurazepam bound equally to sites labeled by agonists and antagonists but desalkylflurazepam, EtOH flurazepam, temazepam, quazepam, and 2-oxo-quazepam did not; in addition, these four compounds did not bind to the "peripheral" BDZ site labeled by Ro 5-4864. BDZ hypnotics differ in their receptor subtype and ligand binding characteristics.

Kinetics, brain uptake, and receptor binding of tandospirone and its metabolite 1-(2-pyrimidinyl)-piperazine

Tandospirone is an azaspirodecanedione derivative under investigation as an antidepressant. Metabolism of tandospirone in humans and rodents leads to 1-(2-pyrimidinyl)-piperazine (1-PP), presumed to have pharmacologic activity. To determine the relative contributions of tandospirone and 1-PP after tandospirone administration, we evaluated open-field activity, pharmacokinetics, and receptor binding of tandospirone and 1-PP in a mouse model. Tandospirone significantly reduced open-field activity during 30 minutes at doses of 1-20 mg/kg. 1-PP had no significant effect on activity except for a trend toward reduction at 20 mg/kg. At 30 minutes after administration, plasma and cortex concentrations of tandospirone and 1-PP increased in proportion to dose. Plasma protein binding (free fraction) for tandospirone was 30.4%, and for 1-PP, 87.5%. Receptor binding studies indicated that tandospirone bound with high affinity to serotonin1A sites, and with low affinity to serotonin2, alpha 1, alpha 2, and benzodiazepine sites. 1-PP bound with high affinity to alpha 2 sites and with low affinity to the other sites evaluated. A "receptor occupancy index" of tandospirone cortex concentrations divided by receptor affinity suggests that after acute administration of tandospirone, effects are likely to be due to the parent compound rather than to the metabolite. Similar conclusions are likely to be correct for other azaspirodecanediones, including buspirone.

Oxaprozin: a once-daily nonsteroidal anti-inflammatory drug

The pharmacology, pharmacokinetics, clinical efficacy, adverse effects, and dosage of oxaprozin are reviewed. Oxaprozin, a nonsteroidal anti-inflammatory drug (NSAID) under consideration for approval by the Food and Drug Administration, is characterized as a propionic acid. By inhibiting cyclo-oxygenase, oxaprozin decreases the formation of prostaglandin (PG) precursors from arachidonic acid, resulting in decreased PG biosynthesis and reduced pain and inflammatory responses. Oxaprozin is well absorbed after oral administration, and peak plasma concentration is reached in three to six hours. Oxaprozin is primarily eliminated by urinary excretion of the unchanged drug. It has a long elimination half-life and persists in synovial fluid. In clinical studies, oxaprozin was equally or more effective than aspirin and as effective as naproxen in the treatment of rheumatoid arthritis. For treatment of osteoarthritis, oxaprozin was as effective as naproxen and more effective than aspirin or piroxicam. Studies have also shown oxaprozin to be effective therapy for juvenile rheumatoid arthritis and ankylosing spondylitis. Oxaprozin, like other NSAIDs, can cause gastrointestinal adverse effects. Other possible adverse effects include allergic reactions, analgesic nephropathy, hepatotoxicity, and increased bleeding times. For adults, the anticipated daily dosage is 600-1200 mg given as a single dose for rheumatoid arthritis, osteoarthritis, and analgesia. In children, oxaprozin 10-20 mg/kg/day has been used to treat juvenile rheumatoid arthritis. Oxaprozin is as effective as other NSAIDs and offers once-daily dosing; however, it does not offer any therapeutic advantage over other currently available NSAIDs.

Chronic benzodiazepine administration. X. Concurrent administration of the peripheral-type benzodiazepine ligand PK11195 attenuates chronic effects of lorazepam

Chronic administration of benzodiazepine active at the tau-aminobutyric acidA receptor ("central" benzodiazepine sites) is associated with behavioral tolerance and receptor downregulation. Recent reports indicate possible interactions between central sites and benzodiazepines active at "peripheral-type" sites located primarily on non-neuronal cells. To evaluate these interactions during chronic administration, we treated mice with lorazepam for 1 to 14 days alone or in combination with the peripheral-type site ligand PK11195 [N-methyl-N-(methyl-1-propyl)chloro-2-phenyl-1-isoquinoline-3-carboxamid e]. Lorazepam was associated with tolerance at 7 days, but tolerance was not observed during concurrent administration of PK11195. Lorazepam was also associated with benzodiazepine receptor down-regulation in cortex and hippocampus at 7 days. With concurrent administration of PK11195, this effect remained in cortex but was absent in hippocampus. tau-Aminobutyric acid-dependent chloride uptake was reduced in both cortex and hippocampus with lorazepam, but not with concurrent lorazepam and PK11195. PK11195 administration alone did not affect behavior or neurochemical parameters, or did it alter brain lorazepam concentrations. These data indicate that concurrent PK11195 administration attenuates behavioral and neurochemical effects of chronic lorazepam administration.

Chronic low-dose alprazolam augments gamma-aminobutyric acid(A) receptor function

After acute administration of low doses, alprazolam displays unusual behavioral and neurochemical characteristics. To determine whether chronic low-dose alprazolam has unique effects, we treated mice for 1-14 days with alprazolam 0.2 mg/kg per day and evaluated open-field activity, benzodiazepine receptor binding, t-butylbicyclophosphorothionate binding, and muscimol-stimulated chloride uptake. Open-field activity in treated mice was similar to that of control mice at each timepoint during alprazolam administration. Similarly, benzodiazepine receptor binding in vivo was unchanged in five brain regions. Benzodiazepine receptor binding in vivo was unchanged in five brain regions. Benzodiazepine binding in vitro in the cortex was unaffected by alprazolam treatment, as was t-butylbicyclophosphorothionate binding in the cortex. However, muscimol-stimulated chloride uptake was increased after 2 and 4 days of alprazolam compared with results after 1, 7, and 14 days. These results are consistent with prior reports of unusual effects of low-dose alprazolam and extend these findings to chronic administration.

Persistent dystonia possibly induced by flecainide

A 55-year-old man developed clicking of his teeth, involuntary biting, chewing and grimacing within three days of initiation of flecainide. We suggest flecainide should be added to the list of benzamide derivatives associated with drug-induced movement disorders.

Increased GABAA-dependent chloride uptake in mice selectively bred for low aggressive behavior

Selective breeding for aggressive behavior alters GABA-dependent chloride uptake and behavioral response to benzodiazepine treatment. Pharmacological and biochemical studies examined subjects from three lines of adult male ICR mice selectively bred for either high levels or low levels of aggressive behavior, as well as unselected controls. Selective breeding produced two lines of behaviorally distinct males. During 5-min dyadic confrontations with an outbred stimulus animal, untreated low-aggressive mice spent more time in walking, rearing, and social interaction than untreated high-aggressive mice. The three lines also showed different responsiveness to the aggression increasing and decreasing effects as well as the sedative effects of benzodiazepine treatment. High doses of chlordiazepoxide (17, 30 mg/kg) reduced motor behaviors (walk, rear and groom) in the low-aggressive line without altering these behaviors in the high aggressive line. In the high-aggressive line, the same doses of chlordiazepoxide (17, 30 mg/kg) produced a behavioral shift; aggressive behaviors were reduced while social behaviors increased to levels similar to the untreated low-aggressive line. In contrast, only the unselected line pursued and threatened more after a low dose of chlordiazepoxide (3 mg/kg). The three lines also showed alterations at the GABAA-benzodiazepine receptor complex. Specific uptake of [3H]Ro-15-1788 was increased in cerebral cortex, hypothalamus and hippocampus in the low-aggressive line, and was reduced in these areas in high-aggressive line when compared with unselected controls. Similarly, GABA-dependent chloride uptake in cortical synaptoneurosomes was augmented in low-aggressive mice and decreased in high-aggressive mice when compared to unselected controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Sleep disturbances and epileptiform activity in a subpopulation of children with attention deficit hyperactivity disorder (ADHD): a literature review generating an hypothesis with implications for drug therapy

The use of electroencephalography and sleep studies in attention deficit hyperactivity disorder (ADHD), and the associated behavioral disorders is reviewed. Based on the available literature, we propose a hypothesis indicating four subtypes of ADHD. The usefulness of EEGs and sleep laboratory indices in detecting a subgroup of patients with submaximal responses to methylphenidate is also discussed.

Chronic benzodiazepine administration. IX. Attenuation of alprazolam discontinuation effects by carbamazepine

Clinical studies suggest that carbamazepine may attenuate effects of alprazolam discontinuation. Since discontinuation of chronic alprazolam in a mouse model is associated with behavioral alterations and upregulation at the gamma-aminobutyric acidA (GABAA) receptor, we studied the effects of carbamazepine administration after alprazolam (2 mg/kg/day) discontinuation. Open-field activity was increased in mice 4 days after alprazolam discontinuation, but this effect was reduced significantly by continuous infusion of carbamazepine, 25 or 100 mg/kg/day. Benzodiazepine receptor binding in vivo was increased in cortex at 2 and 4 days after alprazolam discontinuation, and in hypothalamus at 4 days; with carbamazepine, 100 mg/kg/day, binding in both regions at these time points was similar to control values. Similar results were observed in cortex with benzodiazepine receptor binding in vitro. GABA-dependent chloride uptake was also increased at 4 days alprazolam administration. Treatment with carbamazepine attenuated (P less than 0.10) this increase. Carbamazepine alone after vehicle did not alter benzodiazepine binding or GABA-dependent chloride uptake. These results indicate that carbamazepine administration after alprazolam discontinuation attenuates behavioral and neurochemical alterations associated with discontinuation.

Platelet activating factor antagonists interact with GABAA receptors

Platelet activating factor (PAF) is ubiquitous in mammals, and may have multiple functions in the central nervous system. Triazolobenzodiazepine compounds are active both at the GABAA receptor and as PAF antagonists. To investigate whether PAF antagonist activity is involved in the actions of triazolobenzodiazepines, we examined effects of two non-benzodiazepine PAF antagonists on binding and function at the GABAA receptor. The gingkolide terpene, BN 52021 and the dioxolane-based compound BN 52115 had no effect on benzodiazepine binding or chloride channel binding in cortical membrane preparations. However, chloride uptake into cortical synaptoneurosomes was enhanced with 1 microM BN 52021 but not 1 microM BN 52115. The effect of BN 52021 was prevented by 1 microM flumazenil. PAF antagonists appear to augment GABAA receptor function without affecting binding.

Naproxen-associated nightmares

We have reported what we believe to be the first case of naproxen-associated nightmares. Our brief review of basic sleep physiology and the several questions we have raised might help explain this seemingly unusual adverse effect of naproxen.

Prenatal benzodiazepine administration. II. Lorazepam exposure is associated with decreases in [35S]TBPS binding but not benzodiazepine binding

Prenatal benzodiazepine exposure has been associated with neurobehavioral alterations in humans and animals. To determine effects of prenatal benzodiazepine exposure on binding at the benzodiazepine and t-butylbicyclophosphorothionate (TBPS) sites on the GABAA receptor in mature offspring, we treated mice with lorazepam, 2 mg/kg/day, during days 13-20 of gestation. Binding was assessed at 6 weeks of age. There were no differences among controls, vehicle- or lorazepam-exposed mice in benzodiazepine receptor binding determined in vivo or in vitro. However, receptor density for [35S]TBPS binding sites was decreased in lorazepam-exposed offspring compared to the other groups. These data are consistent with prior neurochemical results indicating decreased TBPS binding and GABAA receptor function in several systems.

Chronic benzodiazepine administration. VIII. Receptor upregulation produced by chronic exposure to the inverse agonist FG-7142

Treatment with benzodiazepine agonists is associated with the development of behavioral tolerance and receptor downregulation, whereas antagonist administration has been reported to lead to increased activity and receptor upregulation. To determine the effects of chronic inverse agonist administration, mice were treated with FG-7142 (20 mg/kg/day) by implanted s.c. osmotic pumps for 1 to 14 days. No seizures were observed in FG-7142-exposed animals. Open-field activity was unchanged as compared to controls at days 1 and 2, but was elevated significantly at days 4 and 7. Activity was reduced below control values at day 14. Benzodiazepine receptor binding determined in vivo was unchanged for days 1, 4 and 7 within the hippocampus but was elevated at day 14. Binding remained unchanged in the cortex, cerebellum, hypothalamus and pons-medulla for the duration of drug exposure. Cortical benzodiazepine binding assessed in vitro was unchanged at days 1 and 2 but increased at days 4, 7 and 14 vs. vehicle treated controls. Binding at the gamma-aminobutyric acid site was increased at day 7 whereas binding of t-[35S]butylbicyclophosphoro-thionate was increased at days 7 and 14 of FG-7142 exposure. Maximal muscimol-slimulated [36Cl-] uptake was elevated at days 4, 7 and 14 compared to day 1 of exposure. These results demonstrate that chronic continuous exposure to FG-7142 is associated with an absence of kindled seizures and with behavioral and neurochemical changes indicative of gamma-aminobutyric acidA receptor upregulation.

Chronic exposure to a benzodiazepine partial agonist does not alter GABAA receptor function in cultured neurons

The benzodiazepine partial agonist Ro16-6028 does not lead to GABAA receptor downregulation in vivo. To assess effects of this compound in vitro, cultured neurons were exposed to Ro16-6028, 1 and 10 microM. GABA-dependent chloride uptake was unaffected at either dose of Ro16-6028 from 2 to 10 days, in contrast to decreased function observed with clonazepam, 1 microM, at 10 days, Ro16-6028 exposure did not alter GABA-independent chloride uptake, total neuronal protein, or cellular protein synthesis.

Decreased GABAA receptor subunit mRNA concentrations following chronic lorazepam administration

Chronic benzodiazepine administration has been associated with alterations in binding and function at the GABAA receptor. To evaluate effects of chronic benzodiazepine exposure on messenger RNA (mRNA) concentrations for several GABAA receptor subunits, we treated mice with lorazepam, 2 mg kg-1 daily for 1-28 days and evaluated mRNAs for the alpha 1 and gamma 2 subunits by Northern hybridization. In cerebral cortex, concentrations of mRNA for the alpha 1 and gamma 2 subunits were unchanged from vehicle or control after 1-10 days of lorazepam. However, after 14 days of treatment mRNA concentrations for both subunits decreased to approximately 50% of control values and remained decreased at 28 days. In contrast, no significant alterations were observed for either subunit mRNA in hippocampus or cerebellum over the same time course. Alterations in mRNAs in cortex occur after the development of tolerance and receptor downregulation in this model.

Chronic benzodiazepine administration: from the patient to the gene

Chronic benzodiazepine administration is associated with the development of tolerance and dependence. To evaluate the cellular mechanisms for these phenomena the authors developed a mouse model of chronic benzodiazepine exposure. The benzodiazepine agonists lorazepam, alprazolam, and clonazepam produced tolerance in this system, which was associated in each case with benzodiazepine and GABAA receptor downregulation. After discontinuation, a syndrome that included increased motor activity and receptor upregulation occurred with each of these compounds. A benzodiazepine antagonist, flumazenil, and an inverse agonist, FG 7142, were associated with receptor upregulation and increased activity during chronic administration. In contrast, a partial agonist (Ro16-6028) did not produce tolerance or receptor changes. Similar results were obtained in a culture system for clonazepam, flumazenil, and FG 7142. The increase in receptor binding after lorazepam discontinuation may be due to enhanced receptor synthesis. Changes in gene expression for GABAA receptor subunits also occur with chronic lorazepam administration, and they follow alterations in binding.

Persistent elevation in GABAA receptor subunit mRNAs following social stress

Stress is associated with alterations in GABA/benzodiazepine binding and function. We evaluated effects of social stress on GABAA receptor subunit (alpha 1 and gamma 2) mRNAs by Northern hybridization. In cortex, no change was observed in either subunit mRNA immediately after stress, but a 4 hours mRNAs for both subunits were increased. These changes persisted for 72 hours after stress, and returned to baseline levels at 7 days. No changes in mRNAs were observed in sham-treated mice. No changes in either subunit mRNA were observed in stressed or sham-treated mice in cerebellum or hippocampus. In undefeated resident mice, mRNAs for both subunits in cortex were unaffected at 24 hours after the stress episode. Social stress is associated with increases in GABAA receptor alpha 1 and gamma 2 subunit mRNAs in cortex.