Secondary Pharmacological Effects Research Articles

Non-clinical safety evaluation of intranasal iota-carrageenan.

Carrageenan has been widely used as food additive for decades and therefore, an extended oral data set is available in the public domain. Less data are available for other routes of administration, especially intranasal administration. The current publication describes the non-clinical safety and toxicity of native (non-degraded) iota-carrageenan when applied intranasally or via inhalation. Intranasally applied iota-carrageenan is a topically applied, locally acting compound with no need of systemic bioavailability for the drug’s action. Animal experiments included repeated dose local tolerance and toxicity studies with intranasally applied 0.12% iota-carrageenan for 7 or 28 days in New Zealand White rabbits and nebulized 0.12% iota-carrageenan administered to F344 rats for 7 days. Permeation studies revealed no penetration of iota-carrageenan across nasal mucosa, demonstrating that iota-carrageenan does not reach the blood stream. Consistent with this, no relevant toxic or secondary pharmacological effects due to systemic exposure were observed in the rabbit or rat repeated dose toxicity studies. Data do not provide any evidence for local intolerance or toxicity, when carrageenan is applied intranasally or by inhalation. No signs for immunogenicity or immunotoxicity have been observed in the in vivo studies. This is substantiated by in vitro assays showing no stimulation of a panel of pro-inflammatory cytokines by iota-carrageenan. In conclusion, 0.12% iota-carrageenan is safe for clinical use via intranasal application.

Preclinical safety pharmacology studies on the rapid-acting insulin analogue insulin aspart.

[B28 Asp]-human insulin (insulin aspart, CAS 116094-23-6, X14) is a rapidly absorbed analogue of human insulin currently undergoing development for the treatment of diabetes mellitus. Cardiovascular studies and a range of standard behavioural, neurological and organ function tests were conducted in various animal species to investigate potential secondary pharmacological effects of insulin aspart. Single intravenous injections (to ensure maximum bioavailability) of a range of doses of insulin aspart were compared with a soluble human insulin preparation. The validity of the test systems was always tested with appropriate positive and/or negative (vehicle) control compounds. Secondary effects due to hypoglycaemia were identified by simultaneous administration of a glucose solution along with the highest dose of insulin aspart and the vehicle as negative control. No safety issues were raised by these experiments; insulin aspart and soluble human insulin exhibited similar pharmacological profiles throughout.

Pharmacology of the Phosphate Binder, Lanthanum Carbonate

Studies were conducted to compare the phosphate-binding efficacy of lanthanum carbonate directly with other clinically used phosphate binders and to evaluate any potential adverse pharmacology. To examine the phosphate-binding efficacy, rats with normal renal function and chronic renal failure received lanthanum carbonate, aluminum hydroxide, calcium carbonate, or sevelamer hydrochloride in several experimental models. Lanthanum carbonate and aluminum hydroxide markedly increased excretion of [32P]-phosphate in feces and reduced excretion in urine in rats with normal renal function (p < 0.05), indicating good dietary phosphate-binding efficacy. In rats with chronic renal failure, lanthanum carbonate and aluminum hydroxide reduced urinary phosphate excretion to a greater degree and more rapidly than calcium carbonate, which in turn was more effective than sevelamer hydrochloride. The potential to induce adverse pharmacological effects was assessed systematically in mice, rats, and dogs with normal renal function using standard in vivo models. There was no evidence of any adverse secondary pharmacological effects of lanthanum carbonate on the central nervous, cardiovascular, respiratory, or gastrointestinal systems. These studies indicate that lanthanum carbonate is the more potent of the currently available dietary phosphate binders. No adverse secondary pharmacological actions were observed in vivo in a systematic evaluation at high doses.

SEEING THROUGH THE MIST: ABUNDANCE VERSUS PERCENTAGE. COMMENTARY ON METABOLITES IN SAFETY TESTING

Recent attention has been given to the potential roles that metabolites could play in safety evaluations of new drugs. In 2002, a proposal was published on "metabolites in safety testing" ("MIST"), which suggested some guidelines regarding when it is necessary to provide greater assessment of the safety of metabolites. However, this proposal was based on relative abundance values, i.e., the percentage that a metabolite comprises of total exposure to drug-related material. In the present commentary, we propose that absolute abundance criteria be used rather than relative abundance. The absolute abundance of a metabolite in circulation or excreta in humans should be combined with other information regarding the chemical structure of the metabolite (e.g., similarity to the parent drug, presence of chemically reactive substituents) and potential mechanisms of toxicity (e.g., suprapharmacological effects, secondary pharmacological effects, nonspecific effects). Decision trees are described that can be used to address human metabolites in safety testing.

Lack of awareness of community-acquired adverse drug reactions upon hospital admission : dimensions and consequences of a dilemma.

Adverse drug reactions (ADRs) are a well-known cause of hospital admission. Nevertheless a quantitative estimate of the preventability of and physicians' awareness of these reactions is lacking. Using intensive bedside and computer-assisted drug surveillance methods a 13-month prospective pharmacoepidemiological survey was carried out on patients admitted to two medical wards of the Erlangen-Nuremberg University Hospital in Erlangen, Germany. This study aimed to define the incidence of preventable and unavoidable ADRs. In addition we investigated the awareness of the physicians to ADRs at the time of admission and the rate of contraindicated pre-admission prescriptions. In 78 (8.5%) of 915 (10.9%) admissions a total of 102 (42 preventable) community-acquired ADRs were detected on admission. In 45 (3.8%) of the admissions ADRs led directly to hospitalisation. 56.9% of the ADRs were not recognised by the attending physician on admission. Marked correlation was found between the awareness of ADRs and their probability and severity scores (r = 0.85 and r = 0.94, respectively; p < 0.05). The most frequently detected ADRs were due to direct toxicity and secondary pharmacological effects. Idiosyncratic reactions were often missed and 18.6% of all drugs prescribed prior to admission were contraindicated. Leading the list were diuretics, analgesics/NSAIDs and antipsychotics/sedatives. Awareness of existing ADRs on hospital admission and appropriate prescribing prior to hospital admission require attention. Early detection of ADRs on hospital admission can be achieved by the use of computer support systems. Many ADRs could be prevented by adhering to indications and contraindications.

Effects of the 5-HT2A agonist psilocybin on mismatch negativity generation and AX-continuous performance task: implications for the neuropharmacology of cognitive deficits in schizophrenia.

Previously the NMDA (N-methyl-D-aspartate) receptor (NMDAR) antagonist ketamine was shown to disrupt generation of the auditory event-related potential (ERP) mismatch negativity (MMN) and the performance of an 'AX'-type continuous performance test (AX-CPT)--measures of auditory and visual context-dependent information processing--in a similar manner as observed in schizophrenia. This placebo-controlled study investigated effects of the 5-HT(2A) receptor agonist psilocybin on the same measures in 18 healthy volunteers. Psilocybin administration induced significant performance deficits in the AX-CPT, but failed to reduce MMN generation significantly. These results indirectly support evidence that deficient MMN generation in schizophrenia may be a relatively distinct manifestation of deficient NMDAR functioning. In contrast, secondary pharmacological effects shared by NMDAR antagonists and the 5-HT(2A) agonist (ie disruption of glutamatergic neurotransmission) may be the mechanism underlying impairments in AX-CPT performance observed during both psilocybin and ketamine administration. Comparable deficits in schizophrenia may result from independent dysfunctions of 5-HT(2A) and NMDAR-related neurotransmission.

Recent developments in the use and abuse of growth promoters

During the last few years, control within the European Union (EU) for illegal growth promoters in cattle and pigs revealed only a limited number of positives. Analysis of illegal preparations, however, showed that steroids, often (esters of) natural hormones, and β-agonists are still used. Corticosteroids, controlled to a much lesser extent, seem to have become the most important group, while even thyreostats remain. Alarming information was obtained from specific investigations in which a large variety of products were found, some of which had never been reported to be misused in the field of growth promotion. For β-agonists and quinoxaline compounds, analogues of known compounds are synthesised. Other compounds are readily available as they are registered as growth promoters in some countries outside Europe or are allowed for specific veterinary purposes. Some classes of veterinary drugs are misused for their secondary pharmacological effects, e.g. benzodiazepines as feed intake enhancers and non-steroidal anti-inflammatory drugs (NSAIDs) as pale meat-making agents. Several non-traditional substances are suspected to be used in the field of breeding animals. This is the case for growth hormones (GHs) and all substances acting over this anabolic compound, as for instance, orally GH secretagogue. Moreover, ecdysteroids, which according to old Russian studies, have anabolic activity, are actually very easy to purchase on the Internet. Recent findings in different classes of growth promoters are discussed in detail.

Adverse drug reactions in patients with gastroenterological diseases: does age increase the risk?

It has been claimed that the risk of adverse drug reactions increases with age. However, only limited data exist for disease-group specific risks and none for patients with liver and gastrointestinal diseases. To determine the incidence and characteristics of adverse drug reactions and the physicians' awareness of adverse drug reactions. During a 7-month period, a prospective survey of 532 male patients (158 aged 65 years or older; 30%) was conducted on a hepatogastroenterological ward of a tertiary-care university hospital, using intensive bedside and computer-assisted drug surveillance methods. No difference was found in the overall rate of adverse drug reactions between older and younger patients (25.9% vs. 24.2%) during 6213 treatment days. However, a significantly higher risk for developing adverse drug reactions could be shown for the elderly with biliary tract diseases (P < 0.01). Independently of age, patients suffering from gastric ulcers, acute episodes of pancreatitis, cholangitis or inflammatory bowel diseases were at high risk of adverse drug reactions. Adverse drug reaction-associated mortality was encountered in four elderly and none of the younger patients. Secondary pharmacological effects and drug toxicity were the main types of adverse drug reactions for both age groups. Although 75.3% of the adverse drug reactions were predictable, only 37.5% of all adverse drug reactions were recognized by the staff physicians. In hepatogastroenterological patients, advancing age was not associated with an overall increased risk of adverse drug reactions except for patients with biliary tract diseases. In the elderly, adverse drug reactions were more severe and carried higher mortality. Guidelines and educational programs should be developed to increase the awareness of adverse drug reactions and their prevention, especially in high risk patients and, thus, to improve patient outcomes.

Clinical and regulatory perspectives on general/safety pharmacology tests: Results of a pharmaceutical industry survey

AbstractGeneral/safety pharmacology is an emerging discipline within the pharmaceutical industry in which unanticipated effects of new drug candidates on major organ function (i.e., secondary pharmacological effects) are critically assessed in a variety of animal models. A survey was conducted to obtain customer input on the role and strategies of this emerging discipline. Four surveys were distributed to each of 30 U.S. pharmaceutical companies. Two surveys went to individuals within the regulatory department, and two went to individuals within the clinical department of each company. All responses were returned anonymously to the survey authors. Sixty‐six responses from at least 19 different companies were obtained. The responses from the clinical and regulatory departments were essentially the same and led to the following conclusions: (1) Major organ functions are monitored routinely in clinical trials to assess potential adverse drug effects; (2) major organ function studies are considered an essential part of non‐clinical drug safety testing; (3) respiratory, gastrointestinal, autonomic, and endocrine evaluations are considered an important part of major organ function studies, whereas cardiovascular, renal and central nervous evaluations are considered essential; (4) non‐clinical testing of these major organ functions should be conducted early in drug development, preferably before initiation of clinical trials; and (5) organ function investigations involving mechanisms of secondary pharmacological effects or drug interaction are considered an important part of general/safety pharmacology testing. © 1995 Wiley‐Liss, Inc.

General pharmacology, the international regulatory environment, and harmonization of guidelines

AbstractThe performance of general pharmacology procedures on new drug candidates supports both drug discovery and safety assessment activities; however, the potential contribution of general pharmacology to safety assessment has had less attention than other aspects of non‐clinical testing. Pharmaceutical companies are divided as to whether or not general pharmacology is integrated with the rest of toxicology testing or carried out as part of the discovery program, and, recently, discussions have taken place within Europe as to whether or not these studies should be subject to Good Laboratory Practice (GLP) conditions. All three regions (the United States, Europe, and Japan) require data on the pharmacological properties of new drugs to be included in a marketing application. This should cover primary and secondary pharmacological effects, and should provide information concerning potential adverse reactions. In addition, Europe and the United States request non‐clinical data on potential drug interactions. However, the most detailed requirements are described in the Japanese guidelines. This paper reviews the current regulatory environment in the European Community (EC), Japan, and the United States, highlighting some general features of the three regulatory systems which are relevant to general pharmacology, and summarising the specific guidelines for these studies in the three regions. Although there are significant differences between the detailed Japanese general pharmacology requirements and the more flexible Western approach, it is not clear that it is appropriate to include general pharmacology within the international harmonization discussions. Rather, deregulation in this area is a desirable goal for the future.

(2R,5R)-6-heptyne-2,5-diamine, an extremely potent inhibitor of mammalian ornithine decarboxylase

It was previously shown that 5-hexyne-1,4-diamine is a potent enzyme-activated irreversible inhibitor of mammalian ornithine decarboxylase. However this compound has secondary pharmacological effects owing to its in vivo oxidation to 4-aminohex-5-ynoic acid, an irreversible inhibitor of 4-aminobutyrate aminotransferase. The first step of this oxidation is catalysed by mitochondrial monoamine oxidase. The monomethyl and dimethyl analogues of 5-hexyne-1,4-diamine, i.e. 6-heptyne-2,5-diamine and 2-methyl-6-heptyne-2,5-diamine, which cannot be substrate of monoamine oxidase, were tested as selective irreversible inhibitors of ornithine decarboxylase. Our results demonstrate that (2R,5R)-6-heptyne-2,5-diamine is greater than 10 times more potent, both in vitro and in vivo , than α-difluoromethylornithine, the most widely used irreversible inhibitor of this enzyme.