Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.6.3.44 (P-glycoprotein)
 13,344 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Recently, a study of docetaxel in combination with the new orally administered P-glycoprotein (P-gp) inhibitor R101933 showed that this combination was feasible. However, due to the low oral bioavailability of R101933 and high interpatient variability, no further attempts to increase the level of P-gp inhibition were made. Here, we assessed the feasibility of combining docetaxel with intravenously (i.v.) administered R101933, and determined the disposition of docetaxel with and without the P-gp inhibitor. Patients received i.v. R101933 alone at a dose escalated from 250 to 500 mg on day 1 (cycle 0), docetaxel 100 mg/m(2) as a 1-h infusion on day 8 (cycle 1) and the combination every 3 weeks thereafter (cycle 2 and further cycles). 12 patients were entered into the study, of whom 9 received the combination treatment. Single treatment with i.v. R101933 was associated with minimal toxicity consisting of temporary drowsiness and somnolence. Dose-limiting toxicity consisting of neutropenic fever was seen in cycles 1 and 2 or in further cycles at both dose levels. The plasma pharmacokinetics of docetaxel were not changed by the R101933 regimen at any dose level tested, as indicated by plasma clearance values of 22.5+/-6.2 l/h/m(2) and 24.2+/-7.4 l/h/m(2) (P=0.38) in cycles 1 and 2, respectively. However, the faecal excretion of unchanged docetaxel decreased significantly after the combination treatment from 2.5+/-2.1% to less than 1% of the administered dose of docetaxel, most likely due to inhibition of the intestinal P-gp by R101933. Plasma concentrations of R101933 were not different in cycles 0 or 2 and the concentrations achieved in the first 12-h period after i.v. infusion were capable of inhibiting P-gp in an ex vivo assay. We conclude that the combination of 100 mg/m(2) i.v. docetaxel and 500 mg i.v. R101933 is feasible, lacks pharmacokinetic interaction in plasma, and shows evidence of P-gp inhibition both in an ex vivo assay and in vivo as indicated by the inhibition of intestinal P-gp.
 ...
PMID:Disposition of docetaxel in the presence of P-glycoprotein inhibition by intravenous administration of R101933. 1200 97

Drug development in neuro-oncology remains a challenge for neoplasms of the central nervous system (CNS). Drugs can be administered peripherally (i.e., oral or intravenous) or locally (into the tumor or the adjacent neuropil). Each of these routes has advantages and disadvantages. Like the treatment for non-CNS cancers, peripheral side effects are encountered (i.e., diarrhea, myelosuppression, rash); however, there also may be neural-specific side effects for patients that may be acute or delayed (i.e., seizures, somnolence, hearing loss). The nervous system is also a privileged site protected by the blood-brain barrier, so many agents developed for peripheral administration will not penetrate into the CNS due to issues of size, charge, or lack of lipid solubility. In addition, the abnormal vasculature, increased interstitial pressure, and inherent mechanisms of tumor resistance (methyl-guanine-methyl transferase [MGMT], P-glycoprotein, etc.) within brain neoplasms reduce the efficacy of many agents designed for neuro-oncologic indications. Each of these issues alone, and all of them in aggregate, are reasons for the limited success of therapeutic agents directed against CNS tumors despite promising data acquired using cell lines and animal models.
 ...
PMID:Issues in developing drugs for primary brain tumors: barriers and toxicities. 2114 33

Antihistamines have been classifed as first or second generation drugs, according to their pharmacokinetic properties, chemical structure and adverse effects. The adverse effects of antihistamines upon the central nervous system (CNS) depend upon their capacity to cross the blood-brain barrier (BBB) and bind to the central H1 receptors (RH1). This in turn depends on the lipophilicity of the drug molecule, its molecular weight (MW), and affinity for P-glycoprotein (P-gp) (CNS xenobiotic substances extractor protein). First generation antihistamines show scant affinity for P-gp, unlike the second generation molecules which are regarded as P-gp substrates. Histamine in the brain is implicated in many functions (waking-sleep cycle, attention, memory and learning, and the regulation of appetite), with numerous and complex interactions with different types of receptors in different brain areas. Bilastine is a new H1 antihistamine that proves to be effective in treating allergic rhinoconjunctivitis (seasonal and perennial) and urticaria. The imaging studies made, as well as the objective psychomotor tests and subjective assessment of drowsiness, indicate the absence of bilastine action upon the CNS. This fact, and the lack of interaction with benzodiazepines and alcohol, define bilastine as a clinically promising drug with a good safety profile as regards adverse effects upon the CNS.
 ...
PMID:Bilastine and the central nervous system. 2218 45

The most commonly occurring allergic diseases can involve a daytime drowsiness associated with the condition itself. The antihistamines used in their treatment can also have central effects and affect certain occupations concerned with risk, road safety and maritime and air navigation. Cognitive tests, experimental studies and epidemiological data recommend avoiding 1st generation antihistamines for people who must drive regularly and/or professions concerned with safety. Although there are no comparative studies on real driving between 1st and 2nd generation antihistamines, in this type of patients there should be a preference for prescribing those with least possible central effect, especially those which are a good substrate for transmembrane transporter pumps such as P-glycoprotein and therefore have a low capacity for crossing the hematoencephalic barrier, thus allowing a broader window for therapy. In this sense, bilastine is a good P-glycoprotein substrate and shows good tolerance at CNS level, in both psychometric trials and real driving test protocols, even at double the dose recommended in the technical file.
 ...
PMID:Antihistamines in drivers, aircrew and occupations of risk. 2467 92

This review set out to examine published papers detailing the efficacy of bilastine in skin models and urticaria to assess whether it meets the optimal profile for updosing in urticaria, that is, strong clinical efficacy and freedom from unwanted side effects, particularly sedation. Bilastine is a highly effective H1 -antihistamine even when used at the basic dose of 20 mg daily. Its facilitated uptake after oral dosage gives it a rapid onset and long duration of action. In both wheal and flare studies and in urticaria updosing fourfold showed increased effectiveness. With respect to somnolence, bilastine is a substrate for P-glycoprotein, a membrane pump which prevents it crossing the blood-brain barrier. Consequently, bilastine is a practically 'non-sedating' H1 -antihistamine. In conclusion, the excellent profile of bilastine in both efficacy and safety make it the ideal H1 -antihistamine for updosing the daily dose fourfold in difficult-to-treat urticaria as recommended by the EAACI/GA2 LEN/EDF/WAO guideline for the management of urticaria.
 ...
PMID:Bilastine: a new H1 -antihistamine with an optimal profile for updosing in urticaria. 2846 71

Respiratory syncytial virus (RSV) is a major cause of lower respiratory tract infections in young children. Presatovir (previously GS-5806) is a novel, orally administered RSV fusion inhibitor with a favorable safety profile and proven antiviral efficacy in preclinical and clinical studies. In vitro, presatovir is a substrate of the efflux transporters P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) and hepatic uptake transporters organic anion transporting polypeptide (OATP) 1B1 and OATP1B3 and is slowly metabolized by cytochrome P450 (CYP) 3A4 and CYP3A5. This study enrolled 64 healthy subjects to evaluate the effect of cyclosporine, a P-gp, BCRP, and OATP1B1/1B3 inhibitor; rifampin, a strong CYP3A4 and P-gp inducer; efavirenz, a moderate CYP3A4 inducer; and cobicistat, a potent CYP3A inhibitor, on presatovir pharmacokinetics. Presatovir plasma exposures (maximum observed plasma concentration [Cmax ] and area under the plasma concentration-time curve from time 0 extrapolated to infinity [AUCinf ]) were not affected by coadministration of cyclosporine, suggesting presatovir is not a sensitive substrate of P-gp, BCRP, or OATP1B1/1B3. As expected, based on the role of CYP3A in presatovir metabolism, presatovir exposure was increased by cobicistat (122% in AUCinf ), and decreased by rifampin (40.3% in Cmax and 82.5% in AUCinf ) and efavirenz (55.7% in AUCinf ). These data support coadministration of presatovir with inhibitors of P-gp, BCRP, OATP1B1/1B3, or CYP3A, but not with moderate or strong CYP3A4 inducers. Presatovir was well-tolerated with the most common drug-related adverse events of dizziness (n = 12) and somnolence (n = 4) reported during efavirenz treatment.
 ...
PMID:The Drug-Drug Interaction Profile of Presatovir. 2941 63

We currently have a wide range of antidepressants available. However, the mechanisms of action are different, giving a theoretical justification for their combination in the failure of monotherapy. However, the combination of drugs entails, in addition to benefits, an increase in the risk of, for example, drug interactions. Many drug interactions in psychiatry are due to the pharmacokinetic interactions between drugs, where their plasma concentrations are altered by inhibiting or inducing cytochrome P450 isoenzymes, especially CYP2D6 and CYP3A4 and P-glycoprotein. When treating depression, we should consider the risks and benefits of combination therapy in individual patients and take measures to minimize the side effects of medicines. The case report describes a case of a patient who reported significant depression after adding paroxetine and mirtazapine to psychiatric medication. As a theoretical cause, it discusses the possible clinically demonstrated interaction between paroxetine and mirtazapine, which has been clinically manifested by fatigue and pronounced daytime sleepiness.
 ...
PMID:Combination of mirtazapine and paroxetine: possible clinically demonstrated interaction? 3199 99