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PubMedDate not supplied

Med-psych drug-drug interactions update. Antiretrovirals, part III: antiretrovirals and drugs of abuse.

The third in a series reviewing the HIV/AIDS antiretroviral drugs, this report summarizes the interactions between antiretrovirals and common drugs of abuse. In an overview format for primary care physicians and psychiatrists, the metabolism and drug interactions in the context of antiretroviral therapy are presented for the following drugs of abuse: alcohol, benzodiazepines, cocaine, GHB (liquid X), ketamine (special K), LSD (acid), MDMA (Ecstasy), opiates, PCP (angel dust), and THC (marijuana).

Acquired Immunodeficiency Syndrome↗
PubMed2006

Isolation of drug delivery from drug effect: problems of optimizing drug delivery parameters.

A recurring question in the treatment of malignant brain tumors has been whether treatment failure is due to inadequate delivery or ineffective drugs. To isolate these issues, we tested a paradigm in which the "therapeutic" agent was a toxin about which there could be no question of efficacy, provided it was delivered in adequate amounts; we used 10% formalin. We infused 10% formalin into 5- to 8-mm subcutaneous RG-2 and D54-MG gliomas at increasing rates until we achieved 100% tumor cell kill. In RG-2 gliomas, infusions of 10 microl/h x 7 days, and 2, 4, 6, and 8 microl/min x 2 h failed to kill tumors, although growth was delayed, while infusion rates of 12 microl/min x 60 min and 48 microl/min x 15 min produced 100% tumor kill. In D54-MG tumors, infusions of 4, 8, and 24 microl/min produced 100% tumor kill. 14C-Formalin autoradiographs showed a heterogeneous distribution after infusions of 2 microl/min x 2 h, whereas infusions of 48 microl/min x 15 min showed a homogeneous distribution within the tumor, but more than 95% of tissue radioactivity was found in tissue surrounding tumor. Drug delivery remains a major issue in brain tumor treatment: Distribution inhomogeneity, rapid efflux, and consequent treatment failures are likely due to high interstitial fluid pressure. Because the infusion rates being used in the treatment of human brain tumors are low and the tumors are larger, treatment failures can be expected on the basis of inadequate drug delivery alone, regardless of the effectiveness of the drug.

Animals↗
PubMed1999

"Guidance for Industry: For the Submission of Chemistry, Manufacturing and Controls and Establishment Description Information for Human Blood and Blood Components Intended for Transfusion or for Further Manufacture and for the Completion of the Form FDA 356h, 'Application to Market a New Drug, Biologic or an Antibiotic Drug for Human Use;'" availability. Food and Drug Administration, HHS. Notice.

The Food and Drug Administration (FDA) is announcing the availability of a document entitled "Guidance for Industry: For the Submission of Chemistry, Manufacturing and Controls and Establishment Description Information for Human Blood and Blood Components Intended for Transfusion or for Further Manufacture and For the Completion of the Form FDA 356h, 'Application to Market a New Drug, Biologic or an Antibiotic Drug for Human Use.'" This guidance document is intended to assist applicants in the preparation of the content and format of the chemistry, manufacturing, and controls (CMC) section and the establishment description section of a biologics license application (BLA), revised Form FDA 356h, for human blood and blood components intended for transfusion or for further manufacture. In addition, this guidance document provides assistance for the completion of the BLA. This action is part of FDA's continuing effort to achieve the objectives of the President's "Reinventing Government" initiatives and the Food and Drug Administration Modernization Act of 1997 (Modernization Act), to reduce unnecessary burdens for industry without diminishing public health protection.

Blood↗
PubMed2004

Drug-protein adducts: an industry perspective on minimizing the potential for drug bioactivation in drug discovery and development.

It is generally accepted that there is neither a well-defined nor a consistent link between the formation of drug-protein adducts and organ toxicity. Because the potential does exist, however, for these processes to be causally related, the general strategy at Merck Research Laboratories has been to minimize reactive metabolite formation to the extent possible by appropriate structural modification during the lead optimization stage. This requires a flexible approach to defining bioactivation issues in a variety of metabolism vectors and typically involves the initial use of small molecule trapping agents to define the potential for bioactivation. At some point, however, there is a requirement to synthesize a radiolabeled tracer and to undertake covalent binding studies in vitro, usually in liver microsomal (and sometimes hepatocyte) preparations from preclinical species and human, and also in vivo, typically in the rat. This paper serves to provide one pragmatic approach to addressing the issue of bioactivation from an industry viewpoint based on protocols adopted by Merck Research Laboratories. The availability of a dedicated Labeled Compound Synthesis group, coupled to a close working relationship between Drug Metabolism and Medicinal Chemistry, represents a framework within which this perspective becomes viable; the overall aim is to bring safer drugs to patients.

Animals↗
PubMed1999

Internal analgesic, antipyretic, and antirheumatic drug products for over-the-counter human use; final rule for professional labeling of aspirin, buffered aspirin, and aspirin in combination with antacid drug products; technical amendments. Department of Health and Human Services (HHS), Public Health Service (PHS), Food and Drug Administration (FDA). Final rule; technical amendments.

The Food and Drug Administration (FDA) is amending the regulations for internal analgesic, antipyretic, and antirheumatic drug products for over-the-counter (OTC) use to correct inadvertent errors and to clarify the labeling for over-the-counter drug products written for health professionals.

Animals↗
PubMedDate not supplied

Drug targeting to the liver with lactosylated albumins: does the glycoprotein target the drug or is the drug targeting the glycoprotein?

The isolated perfused rat liver preparation was employed to study hepatic disposition of the model drug-carrier conjugate fluorescein-lactosylated albumin (F-LnHSA) with special reference to the influence of the organic anion fluorescein on liver cell specificity of the endocytosed neoglycoprotein. Hepatic clearance of fluoresceinated neoglycoproteins was significantly faster than clearance of radioiodinated neoglycoproteins. Perfusate clearance of F-L7HSA and F-L25HSA could not completely be inhibited by a dose of 10 mg asialoorosomucoid that saturates the hepatocyte receptor-mediated endocytic process. From these data, we inferred an additional hepatic uptake mechanism, competing with the Ashwell-receptor-mediated internalization of galactose-terminated glycoproteins. Clearance experiments with fluoresceinated 125I-human serum albumin in the presence of the polyanionic probe dextran sulfate revealed a nearly complete (approximately 90%) inhibition of hepatic uptake, while also a pronounced effect was obtained with colloidal carbon. These data point to nonparenchymal cell uptake of fluoresceinated protein via interaction with scavenger receptors. In wash-out studies, it was shown that about 25% of ligand sequestrated by sinusoidal liver cells escaped degradation and recycled to the perfusion medium. Our results show that care should be taken in the use of neoglycoproteins as drug carriers to hepatocytes, since a load of only 2 to 3 moles fluorescein per mole neoglycoprotein considerably affects intrahepatic distribution. The relative contribution of nonparenchymal cell uptake by coupling of acidic drugs to the neoglycoproteins is very probably inversely related to the number of exposing galactose groups per molecule neoglycoprotein. This phenomenon of "inversed targeting" could therapeutically both be useful or detrimental, dependent on the spectrum of cell types that should be reached by the drug.

Animals↗
PubMed1995

Regional drug delivery II: relationship between drug targeting index and pharmacokinetic parameters for three non-steroidal anti-inflammatory drugs using the rat air pouch model of inflammation.

PURPOSE: To quantify the advantage gained by direct administration to a target site for two non-steroidal anti-inflammatory drugs (NSAIDs) piroxicam and diclofenac in the rat air pouch model of inflammation. To derive a model relating drug targeting index (DTI) to the pharmacokinetic parameters of the target and systemic sites, and to compare predictions with observations. METHODS: DTI was calculated based on area under the concentration time curve at target (pouch) and systemic site (venous blood) following administration into and sampling from both sites. A model was derived relating DTI to systemic clearance, target permeability, plasma protein binding and fraction of the targeted dose that is systemically available. RESULTS: Both NSAIDs exhibited linear pharmacokinetics over the dose ranges studies. They differed primarily in total body clearance which was approximately 16 fold greater for diclofenac (213 ml hr-1 per 250 g) than piroxicam (13 ml hr-1 per 250 g). Observed DTIs (11, 114 and 276 for piroxicam, S[+]ibuprofen [studied previously] and diclofenac) were ranked in order of total body clearance but were approximately 7.5 fold lower than predicted (101, 700 and 2214 respectively). CONCLUSIONS: The discrepancy was explained by the influx of the plasma binding protein, albumin, into the target site due to increased vascular permeability associated with the inflammatory response. The originally derived equation for DTI, which assumed only unbound drug diffuses across the target site, was modified to take into account the simultaneous flux of bound drug.

Animals↗
PubMed2003

Antiherpesvirus drugs: a promising spectrum of new drugs and drug targets.

In the absence of effective vaccines to control herpesvirus infections, nucleosidic antiviral drugs have been the mainstay of clinical treatment since their development in the late 1970s. However, given the drawbacks of these drugs, including the increasing emergence of drug-resistant clinical isolates, new strategies for treating herpesvirus infections are warranted. A range of promising new drugs with novel molecular targets has been developed, but will they cure latent infections?

Antiviral Agents↗
PubMed2002

Hepatotoxicity of commonly used drugs: nonsteroidal anti-inflammatory drugs, antihypertensives, antidiabetic agents, anticonvulsants, lipid-lowering agents, psychotropic drugs.

Hepatotoxic adverse drug reactions have contributed to the decline of many promising therapies, even among mainstream medication classes (bromfenac and troglitazone are recent examples). The spectrum of nonsteroidal anti-inflammatory drug-related liver toxicity continues to expand, with reports in children, interactive toxicity in persons with hepatitis C, and recognition of the toxicity of both the preferential and selective cyclooxygenase-2 inhibitors. Of the antihypertensive agents, methyldopa is now rarely prescribed and adverse effects are reported infrequently, whereas cases of liver injury associated with the angiotensin receptor and converting enzyme inhibitors are increasingly reported. Of the antidiabetic agents, acarbose, gliclazide, metformin, and human insulin have been implicated in causing liver injury. To date, the newer thiazolidinediones do not appear to share the hepatotoxic potential of troglitazone, although a few reports of acute hepatitis have accrued. Although liver injury has been associated with the "statins," the frequency of such toxicity is lower than that of the background population and the value of biochemical monitoring remains unproved. Newer concepts in anticonvulsant hepatotoxicity have been the recognition of the reactive metabolite syndrome, delineation of the risk factors for valproic acid toxicity, the potential role of carnitine in preventing valproic acid hepatotoxicity, and the toxicity of second-line antiepileptic drugs. Liver injury associated with newer psychotropic agents, particularly the selective serotonin reuptake inhibitors, is also discussed. The focus of the review is the hepatotoxicity of commonly used drugs with particular reference to recent and novel reports of toxicity. Well-known causes of liver injury such as chlorpromazine, phenytoin, and methyldopa are not discussed.

Adult↗
PubMed1993

Epigenetic mechanisms of drug resistance: drug-induced DNA hypermethylation and drug resistance.

In a model system employing Chinese hamster V-79 cells, the DNA synthesis inhibitor 3'-azido-3'-deoxythymidine (BW A509U, AZT) was shown to induce genome-wide DNA hypermethylation, low-frequency silencing of thymidine kinase (TK; EC 2.7.1.21) gene expression, and resistance to AZT. Twenty-four hours of exposure of V-79 cells to 150 microM AZT led to > 2-fold enhancement of genomic 5-methylcytosine levels and produced TK- epimutants at a rate approximately 43-fold above background. Such AZT-induced TK- epimutants were shown to be severely reduced in their capacity to activate AZT to its proximate antiviral form, AZT 5'-monophosphate, as compared with the TK+ parental cell line from which they were derived. TK- clones isolated under these conditions were shown to be 9- to 24-fold more resistant to the cytotoxic effects of AZT than the parental TK+ cell line and showed collateral resistance to 5-fluoro-2'-deoxyuridine. Three of four TK- epimutants could be reactivated at very high frequency (8-73%) to the TK+ AZT-sensitive phenotype by 24 hr of exposure to the demethylating agent 5-azadeoxycytidine (5-azadC), implying that drug-induced DNA hypermethylation, rather than classical mutation, was involved in the original gene-silencing event in these three clones. These 5-azadC-induced TK+ revertants concomitantly regained the ability to metabolize AZT to its 5'-monophosphate. RNA slot blot analyses indicated that the four AZT-induced TK- clones expressed 8.9%, 15.6%, 17.8%, and 11.1% of the parental level of TK mRNA. The three clones that were reactivatable by 5-azadC showed reexpression of TK mRNA to levels 84.4%, 51.1%, and 80.0% that of the TK+ parental cell line. These experiments show that one potential mechanism of drug resistance involves drug-induced DNA hypermethylation and resulting transcriptional inactivation of cellular genes whose products are required for drug activation.

Animals↗
PubMed2005

Box-Behnken experimental design in the development of a nasal drug delivery system of model drug hydroxyurea: characterization of viscosity, in vitro drug release, droplet size, and dynamic surface tension.

The purpose of the research was to investigate the changes in physicochemical properties and their influence on nasal formulation performance using 5-factor, 3-level Box-Behnken experimental design on the combined responses of viscosity, droplet size distribution (DSD), and drug release. Gel formulations of hydroxyurea (HU) with surface-active polymers (hydroxyethylcellulose [HEC] and polyethylene-oxide [PEO]) and ionic excipients (sodium chloride and calcium chloride) were prepared using Box-Behnken experimental design. The rheology and dynamic surface tension (DST) of the test formulations was investigated using LV-DV-III Brookfield rheometer and T60 SITA tensiometer, respectively. Droplet size analysis of nasal aerosols was determined by laser diffraction using the Malvern Spraytec with the InnovaSystems actuator. In vitro drug release studies were conducted on Franz diffusion cells. With PEO gel, calcium chloride increased the viscosity and DSD and retarded drug release, while sodium chloride decreased the viscosity, DST, and DSD and accelerated the release of HU. With HEC gel, the addition of the above salts resulted in less significant changes in viscosity, DSD, and DST, but both salts significantly increased the release of HU. Droplet size data obtained from a high viscosity nasal pump was dependent on type of polymer, polymer-excipient interactions, and solvent properties. The applications of Box-Behnken experimental design facilitated the prediction and identified major excipient influences on viscosity, DSD, and in vitro drug release.

Administration, Intranasal↗
PubMed1999

[Biological addictive drugs--is there a change in drug taking behavior of young drug addicts?].

Abuse of natural products was frequently noticed among young patients with multiple substance abuse. 180 patients of a rehabilitation clinic for young addicts filled out a questionnaire regarding their regularly consumed drugs. Ayahuasca and cactus, the natural drugs of the 70's are rarely found. The patients frequently consumed psilocybin, amanita and datura. We inform about the toxicological basis of the used drugs. A specific exploration of patients with multiple substance abuse in regard to the use of biological drugs is an necessary as random and multicentre follow-up-studies.

Adult↗
PubMed1990

Drug use patterns and demographics of employed drug users: data from the 1988 National Household Survey on Drug Abuse.

This paper has identified some characteristics of full-time working populations who are at higher risk to be substance abusers. In summary, employed people who use drugs are generally between the ages of 18 and 34. Heavy drinkers fall mainly between 18 and 25 years of age. Males are much more likely than females to use marijuana, cocaine, or other illicit drugs and alcohol on a frequent basis. For males, past month use of any illicit drugs and marijuana was higher among those with the lowest personal incomes. For females, past year use of cocaine was higher among those with the highest personal incomes. Females and males with high personal incomes were also more likely than their low income counterparts to use alcohol on a weekly basis. Industries with high percentages of male substance abusers were: construction, wholesale trade, finance, repair services and professionals. Industries with substantial numbers of female drug abusers were manufacturing, retail trade and professionals.

Accidents, Occupational↗