Burkhard Hinz

Acetaminophen (paracetamol) is a selective cyclooxygenase-2 inhibitor in man

For more than three decades, acetaminophen (INN, paracetamol) has been claimed to be devoid of significant inhibition of peripheral prostanoids. Meanwhile, attempts to explain its action by inhibition of a central cyclooxygenase (COX)‐3 have been rejected. The fact that acetaminophen acts functionally as a selective COX‐2 inhibitor led us to investigate the hypothesis of whether it works via preferential COX‐2 blockade. Ex vivo COX inhibition and pharma‐cokinetics of acetaminophen were assessed in 5 volunteers receiving single 1000 mg doses orally. Coagulation‐induced thromboxane B2 and lipopolysaccharide‐induced prostaglandin E2 were measured ex vivo and in vitro in human whole blood as indices of COX‐1 and COX‐2 activity. In vitro, acetaminophen elicited a 4.4‐fold selectivity toward COX‐2 inhibition (IC50= 113.7 μmol/L for COX‐1;IC50 = 25.8 μmol/L for COX‐2). Following oral administration of the drug, maximal ex vivo inhibitions were 56% (COX‐1) and 83% (COX‐2). Acetaminophen plasma concentrations remained above the in vitro IC50 for COX‐2 for at least 5 h postadministration. Ex vivo IC50 values (COX‐1: 105.2 μmol/L; COX‐2: 26.3 μmol/L) of acetaminophen compared favorably with its in vitro IC50 values. In contrast to previous concepts, acetaminophen inhibited COX‐2 by more than 80%, i.e., to a degree comparable to nonste‐roidal antiinflammatory drugs (NSAIDs) and selective COX‐2 inhibitors. However, a >95% COX‐1 blockade relevant for suppression of platelet function was not achieved. Our data may explain acetaminophens analgesic and antiinflammatory action as well as its superior overall gastrointestinal safety profile compared with NSAIDs. In view of its substantial COX‐2 inhibition, recently defined cardiovascular warnings for use of COX‐2 inhibitors should also be considered for acetaminophen.—Hinz, B., Cheremina, O., Brune, K. Acetaminophen (paracetamol) is a selective cyclooxygenase‐2 inhibitor in man. FASEB J. 22, 383–390 (2007)

The Impact of Unlicensed and Off-Label Drug Use on Adverse Drug Reactions in Paediatric Patients

AbstractBackground and objective: Many drugs that are used to treat children are either not licensed for use in paediatric patients (unlicensed) or prescribed outside the terms of the product licence (off label). The incidence of adverse drug reactions (ADRs) associated with the use of such drugs is yet to be established. This study investigates, for the first time in a German patient population, the impact of unlicensed and off-label drug use on ADRs in paediatric patients. Patients and methods: An 8-month prospective pharmacoepidemiological cohort-based survey was conducted on a ten-bed paediatric isolation ward at the University Hospital Erlangen-Nüremberg, Germany. All patients were intensively monitored for ADRs by a pharmacoepidemiological team. ADRs were characterised according to international classification methods. All drug prescriptions were evaluated retrospectively as to unlicensed or off-label use on the basis of the product information. Results: A total of 178 patients were included in the study and 740 drug prescriptions were given to 156 patients (median three prescriptions per patient). In 198 cases (27.7% of all prescriptions) drugs were used in either an unlicensed (n = 3) or off-label (n = 195) manner. A total of 46 ADRs were observed in 31 patients (17.4%). Patients receiving at least one unlicensed or off-label drug prescription during hospitalisation (n = 92) experienced an ADR significantly more frequently (n = 26 patients) than patients receiving only licensed drugs (n = 64 vs 5 patients). ADRs were associated with 29 (5.6%) of the 517 licensed drug prescriptions and with 12 (6.1%) of the 198 unlicensed or off-label drug prescriptions. The majority of ADRs caused by unlicensed and off-label drug use were recognised by the attending physician. However, statistical analysis revealed no significant difference in the number of licensed and unlicensed/off-label drug prescriptions causing ADRs. Conclusion: This study demonstrated that at a paediatric isolation ward the incidence of ADRs caused by unlicensed or off-label drug use was not significantly more than that caused by the licensed drug use. However, patients treated with unlicensed or off-label drugs were shown to possess a significantly increased risk for developing ADRs.

Rapid non-genomic feedback effects of glucocorticoids on CRF-induced ACTH secretion in rats

AbstractPurpose. The present study investigates fast negative feedback actions of corticosterone (corticosteroid type I/type II receptor agonist) and RU 28362 (corticosteroid type II receptor agonist) on corticotropin-releasing factor (CRF)-induced adrenocorticotropic hormone (ACTH) secretion in rats. Methods. To induce fast feedback, glucocorticoids were administered intravenously immediately before injection of the hypophyseotropic stimulus CRF. Plasma ACTH levels, being determined 5 to 30 min thereafter, were used as markers of fast feedback. Results. Fast inhibitory effects on CRF-induced ACTH secretion became evident within 15 min (corticosterone) and 5 min (RU 28362) after steroid administration. Rapid feedback inhibition was also observed in the presence of other corticosteroids (cortisol, dexamethasone, aldosterone), whereas structurally-unrelated steroids (β-estradiol, progesterone, potassium canrenoate, alphaxalone) were inactive in this respect. Pretreatment of rats with the corticosteroid type II receptor antagonist RU 486 or the transcription inhibitor actinomycin D left fast feedback effects unaltered. Conclusions. Our results demonstrate that glucocorticoids exert fast negative feedback at the pituitary level via a mechanism that is independent of corticosteroid type II receptor occupation and de novo synthesis of mRNA. In conclusion, corticosteroid-specific non-genomic effects may underly rapid glucocorticoid responses on CRF-induced ACTH secretion.

Selective cyclooxygenase-2 inhibitors: similarities and differences

The enzyme cyclooxygenase (COX) was shown to exist as two distinct isoforms about a decade ago. COX‐1 is constitutively expressed as a ‘housekeeping’ enzyme in nearly all tissues, and mediates physiological responses (e.g. cytoprotection of the stomach, and platelet aggregation). On the other hand, COX‐2, expressed by cells involved in inflammation (e.g. macrophages, monocytes, synoviocytes), has emerged as the isoform that is primarily responsible for the synthesis of prostanoids involved in acute and chronic inflammatory states. Consequently, the hypothesis that selective inhibition of COX‐2 might have therapeutic actions similar to those of non‐steroidal anti‐inflammatory drugs, but without causing gastrointestinal side effects, was the rationale for the development of selective inhibitors of the COX‐2 isoenzyme. Selective COX‐2 inhibitors currently used in the clinic are the sulphonamides celecoxib and valdecoxib (parecoxib is a prodrug of valdecoxib), as well as the methylsulphones rofecoxib and etoricoxib. Furthermore, the phenylacetic acid derivative lumiracoxib has gained permission recently to be marketed in Europe. This review discusses the clinically relevant similarities and differences of these substances, with particular emphasis on their diverse pharmacokinetic characteristics.

Dipyrone elicits substantial inhibition of peripheral cyclooxygenases in humans: new insights into the pharmacology of an old analgesic

Dipyrone (INN, metamizol) is a common analgesic used worldwide. Its widespread prescription or over‐the‐counter use in many countries (e.g., Brazil, Israel, Mexico, Russia, Spain) requires insight into its mode of action. This study therefore addressed the impact of its metabolites 4‐methyl‐amino‐antipyrine (MAA) and 4‐amino‐antipyrine (AA) on peripheral cyclooxygenases (COX). Pharmacokinetics of metabolites and ex vivo COX inhibition were assessed in five volunteers receiving dipyrone at single oral doses of 500 or 1000 mg. Coagulation‐induced thromboxane B2 formation and lipopolysaccha‐ride‐induced prostaglandin E2 synthesis were measured in vitro and ex vivo in human whole blood as indices of COX‐1 and COX‐2 activity. In vitro, metabolites elicited no substantial COX‐1/COX‐2 selectivity with MAA (IC50 = 2.55 μmol/L for COX‐1;IC50 =4.65 μmol/L for COX‐2), being ~8.2‐ or 9‐fold more potent than AA. After administration of dipyrone, MAA plasma concentrations remained above the IC50 values for each isoform for at least 8 h (500 mg) and 12 h (1000 mg) postdose. COX inhibition correlated with MAAplasma levels (exvivo IC50 values of 1.03 μmol/L [COX‐1] and 0.87 μmol/L [COX‐2]). By contrast, plasma peak concentrations of AA after the 1000 mg dose were 2.8‐ and 6.5‐fold below its IC50 values for COX‐1 and COX‐2, respectively. Maximal inhibitions of COX‐1 and COX‐2 were 94% and 87% (500 mg), 97% and 94% (1000 mg). Taken together, dipyrone elicits a substantial and virtually equipotent inhibition of COX isoforms via MAA. Given the profound COX‐2 suppression by dipyrone, which was considerably above COX‐2 inhibition by single analgesic doses of celecoxib and rofecoxib, a significant portion of its analgesic action may be ascribed to peripheral mechanisms. In view of the observed COX‐1 suppression, physicochemical factors (lack of acidity) rather than differential COX‐1 inhibition may be responsible for dipyrones favorable gastrointestinal tolerability compared with acidic COX inhibitors.—Hinz, B., Cheremina, O., Bachmakov, J., Renner, B., Zolk, O., Fromm, M. F., Brune, K. Dipyrone elicits substantial inhibition of peripheral cyclooxygenases in humans: new insights into the pharmacology of an old analgesic. FASEB J. 21, 2343–2351 (2007)

Cannabidiol inhibits cancer cell invasion via upregulation of tissue inhibitor of matrix metalloproteinases-1.

Although cannabinoids exhibit a broad variety of anticarcinogenic effects, their potential use in cancer therapy is limited by their psychoactive effects. Here we evaluated the impact of cannabidiol, a plant-derived non-psychoactive cannabinoid, on cancer cell invasion. Using Matrigel invasion assays we found a cannabidiol-driven impaired invasion of human cervical cancer (HeLa, C33A) and human lung cancer cells (A549) that was reversed by antagonists to both CB(1) and CB(2) receptors as well as to transient receptor potential vanilloid 1 (TRPV1). The decrease of invasion by cannabidiol appeared concomitantly with upregulation of tissue inhibitor of matrix metalloproteinases-1 (TIMP-1). Knockdown of cannabidiol-induced TIMP-1 expression by siRNA led to a reversal of the cannabidiol-elicited decrease in tumor cell invasiveness, implying a causal link between the TIMP-1-upregulating and anti-invasive action of cannabidiol. P38 and p42/44 mitogen-activated protein kinases were identified as upstream targets conferring TIMP-1 induction and subsequent decreased invasiveness. Additionally, in vivo studies in thymic-aplastic nude mice revealed a significant inhibition of A549 lung metastasis in cannabidiol-treated animals as compared to vehicle-treated controls. Altogether, these findings provide a novel mechanism underlying the anti-invasive action of cannabidiol and imply its use as a therapeutic option for the treatment of highly invasive cancers.

15-Deoxy-Δ12,14-prostaglandin J2 inhibits the expression of proinflammatory genes in human blood monocytes via a PPAR-γ-independent mechanism ☆

The peroxisome proliferator-activated receptor-gamma (PPAR-gamma) has been implicated in inhibition of the expression of proinflammatory cytokines and inducible enzymes such as cyclooxygenase-2 (COX-2). Using real-time RT-PCR the present study investigates the impact of two PPAR-gamma agonists, 15-deoxy-Delta(12,14)-prostaglandin J(2) (15d-PGJ(2)) and ciglitazone, on the expression of several proinflammatory genes in lipopolysaccharide (LPS)-stimulated human blood monocytes. Stimulation of cells with LPS resulted in a profound induction of the expression of COX-2, interleukin (IL)-1, IL-6, tumor necrosis factor (TNF), and granulocyte-macrophage colony-stimulating factor (GM-CSF). Treatment of cells with 15d-PGJ(2) (10 microM) was associated with a nearly complete inhibition of the expression of all genes that remained unaltered in the presence of the PPAR-gamma antagonist bisphenol A diglycidyl ether (BADGE; 100 microM). By contrast, treatment of cells with another potent PPAR-gamma agonist, ciglitazone (50 microM), and the PPAR-alpha agonist WY-14,643 (100 microM) did not suppress LPS-induced expression of the investigated genes. Stimulation of monocytes with LPS resulted in an 88% inhibition of PPAR-gamma mRNA expression that was fully restored by 15d-PGJ(2) but only to a partial extent by ciglitazone and WY-14,643. Again, BADGE did not alter the effect of 15d-PGJ(2). Collectively, our results show that alterations of gene expression by 15d-PGJ(2) in LPS-stimulated human blood monocytes are mediated by PPAR-gamma-independent mechanisms. Moreover, it is concluded that both inhibition of proinflammatory gene expression and restoration of LPS-induced decrease of PPAR-gamma expression may contribute to the biological action of 15d-PGJ(2).

Celecoxib inhibits metabolism of cytochrome P450 2D6 substrate metoprolol in humans

In vitro data have shown that celecoxib inhibits the metabolism of cytochrome P450 (CYP) 2D6 substrates. However, very limited data are available on the influence of cyclooxygenase 2 inhibitors on the disposition of CYP2D6 substrates in humans. Therefore the objective of this study was to examine the effect of celecoxib and rofecoxib on the pharmacokinetics of the clinically relevant CYP2D6 substrate metoprolol.

Paracetamol and cyclooxygenase inhibition: is there a cause for concern?

Paracetamol is recommended as first-line therapy for pain associated with osteoarthrosis and is one of the most widely used over-the-counter analgesic drugs worldwide. Despite its extensive use, its mode of action is still unclear. Although it is commonly stated that paracetamol acts centrally, recent data imply an inhibitory effect on the activity of peripheral prostaglandin-synthesising cyclooxygenase enzymes. In this context paracetamol has been suggested to inhibit both isoforms in tissues with low levels of peroxide by reducing the higher oxidation state of cyclooxygenase enzymes. Two recent studies have also demonstrated a preferential cyclooxygenase 2 (COX-2) inhibition by paracetamol under different clinically relevant conditions. This review attempts to relate data on paracetamols inhibitory action on peripheral cyclooxygenase enzymes to the published literature on its anti-inflammatory action and its hitherto underestimated side-effects elicited by cyclooxygenase inhibition. As a result, a pronounced COX-2 inhibition by paracetamol is expected to occur in the endothelium, possibly explaining its cardiovascular risk in epidemiological studies. A careful analysis of paracetamols cardiovascular side-effects in randomised studies is therefore strongly advised. On the basis of epidemiological data showing an increased gastrointestinal risk of paracetamol at high doses or when co-administered with classic cyclooxygenase inhibitors, paracetamols long-term gastrointestinal impact should be investigated in randomised trials. Finally, paracetamols fast elimination and consequently short-lived COX-2 inhibition, which requires repetitive dosing, should be definitely considered to avoid overdosage leading to hepatotoxicity.

Cannabidiol inhibits lung cancer cell invasion and metastasis via intercellular adhesion molecule-1

Cannabinoids inhibit cancer cell invasion via increasing tissue inhibitor of matrix metalloproteinases‐1 (TIMP‐1). This study investigates the role of intercellular adhesion molecule‐1 (ICAM‐1) within this action. In the lung cancer cell lines A549, H358, and H460, cannabidiol (CBD; 0.001‐3 μM) elicited concentration‐dependent ICAM‐1 up‐regulation compared to vehicle via cannabinoid receptors, transient receptor potential vanilloid 1, and p42/44 mitogen‐activated protein kinase. Up‐regulation of ICAM‐1 mRNA by CBD in A549 was 4‐fold at 3 μM, with significant effects already evident at 0.01 μM. ICAM‐1 induction became significant after 2 h, whereas significant TIMP‐1 mRNA increases were observed only after 48 h. Inhibition of ICAM‐1 by antibody or siRNA approaches reversed the anti‐invasive and TIMP‐1‐up‐regulating action of CBD and the likewise ICAM‐1‐inducing cannabinoids Δ9‐tetrahydrocannabinol and R(+)‐methanandamide when compared to isotype or nonsilencing siRNA controls. ICAM‐1‐dependent anti‐invasive cannabinoid effects were confirmed in primary tumor cells from a lung cancer patient. In athymic nude mice, CBD elicited a 2.6‐ and 3.0‐fold increase of ICAM‐1 and TIMP‐1 protein in A549 xenografts, as compared to vehicle‐treated animals, and an antimetastatic effect that was fully reversed by a neutralizing antibody against ICAM‐1 [% metastatic lung nodules vs. isotype control (100%): 47.7% for CBD + isotype antibody and 106.6% for CBD + ICAM‐1 antibody]. Overall, our data indicate that cannabinoids induce ICAM‐1, thereby conferring TIMP‐1 induction and subsequent decreased cancer cell invasiveness.—Ramer, R., Bublitz, K., Freimuth, N., Merkord, J., Rohde, H., Haustein, M., Borchert, P., Schmuhl, E., Linnebacher, M., Hinz, B. Cannabidiol inhibits lung cancer cell invasion and metastasis via intercellular adhesion molecule‐1. FASEB J. 26, 1535‐1548 (2012). www.fasebj.org