Pharmacokinetics of dolutegravir in HIV-seronegative subjects with severe renal impairment

Purpose

Dolutegravir (DTG), an unboosted HIV integrase inhibitor (INI), is metabolized by UGT1A1 and to a minor extent by CYP3A. Renal elimination of unchanged DTG is very low (< 1 %). As renal impairment may affect pharmacokinetics (PK), even for drugs primarily metabolized or secreted in bile, this study investigated the effect of renal impairment on the PK of DTG.

Methods

This was an open-label, single-dose study of oral DTG 50 mg administered to subjects with severe renal impairment (creatinine clearance [CLcr] <30 mL/min; not on dialysis) and to healthy controls (CLcr >90 mL/min) matched for gender, age and body mass index (8 subjects per group). Serial PK samples were collected up to 72 h post-dose for determination of DTG and DTG-glucuronide (DTG-Gluc) concentrations in plasma. DTG unbound fraction in plasma was determined at 3 and 24 h. PK parameters were determined by non-compartmental methods and compared between groups by analysis of covariance.

Results

DTG was well tolerated with a low incidence of Grade 1 adverse events. DTG PK parameters showed significant overlap between groups. DTG mean exposure was lower in subjects with severe renal impairment compared to healthy, matched subjects: AUC(0-∞) and Cmax were 40 % and 23 % lower, while mean DTG-Gluc was increased. Renal impairment did not affect DTG fraction unbound in plasma.

Conclusions

The modest reductions in mean PK exposures for DTG and increases for DTG-Gluc in the severe renal impairment group are not considered clinically significant. DTG does not require dose adjustment in patients with renal impairment.     

Isolation,synthesis and characterization of ω-TRTX-Cc1a,a novel tarantula venom peptide that selectively targets L-type CaV channels

Spider venoms are replete with peptidic ion channel modulators, often with novel subtype selectivity, making them a rich source of pharmacological tools and drug leads. In a search for subtype-selective blockers of voltage-gated calcium (Ca_V) channels, we isolated and characterized a novel 39-residue peptide, ω-TRTX-Cc1a (Cc1a), from the venom of the tarantula Citharischius crawshayi (now Pelinobius muticus). Cc1a is 67% identical to the spider toxin ω-TRTX-Hg1a, an inhibitor of Ca_V2.3 channels. We assembled Cc1a using a combination of Boc solid-phase peptide synthesis and native chemical ligation. Oxidative folding yielded two stable, slowly interconverting isomers. Cc1a preferentially inhibited Ba²⁺ currents (I_Ba) mediated by L-type (Ca_V1.2 and Ca_V1.3) Ca_V channels heterologously expressed in Xenopus oocytes, with half-maximal inhibitory concentration (IC₅₀) values of 825 nM and 2.24 μM, respectively. In rat dorsal root ganglion neurons, Cc1a inhibited I_Ba mediated by high voltage-activated Ca_V channels but did not affect low voltage-activated T-type Ca_V channels. Cc1a exhibited weak activity at Na_V1.5 and Na_V1.7 voltage-gated sodium (Na_V) channels stably expressed in mammalian HEK or CHO cells, respectively. Experiments with modified Cc1a peptides, truncated at the N-terminus (ΔG1–E5) or C-terminus (ΔW35–V39), demonstrated that the N- and C-termini are important for voltage-gated ion channel modulation. We conclude that Cc1a represents a novel pharmacological tool for probing the structure and function of L-type Ca_V channels.     

Paclitaxel and Carboplatin (TC) Regimen for Ovarian Cancer

The complexity of cancer chemotherapy requires pharmacists be familiar with the complicated regimens and highly toxic agents used. This column reviews various issues related to preparation, dispensing, and administration of antineoplastic therapy, and the agents, both commercially available and investigational, used to treat malignant diseases. Questions or suggestions for topics should be addressed to Dominic A. Solimando, Jr, President, Oncology Pharmacy Services, Inc., 4201 Wilson Blvd #110–545, Arlington, VA 22203, e-mail: ten.tsacmoc@cvSxRcnO; or J. Aubrey Waddell, Professor, University of Tennessee College of Pharmacy; Oncology Pharmacist, Pharmacy Department, Blount Memorial Hospital, 907 E. Lamar Alexander Parkway, Maryville, TN 37804, e-mail: ten.retrahc@ruofddaw.Regimen Name: Paclitaxel and CarboplatinSynonym: TCOrigin of Name: TC is an acronym for the 2 medications in the regimen: paclitaxel (Taxol) and carboplatin.     

Electricians’ chrysotile asbestos exposure from electrical products and risks of mesothelioma and lung cancer

Both mechanistic and epidemiology studies indicate chrysotile asbestos has a threshold below which it does not cause mesothelioma or lung cancer. We conducted a critical review to determine whether electricians are at increased risk for these cancers and, if so, whether their exposure to chrysotile in electrical products could be responsible. We found that most, but not all, epidemiology studies indicate electricians are at increased risk for both cancers. Studies that evaluated electricians’ exposure to asbestos during normal work tasks have generally reported low concentrations in air; an experimental study showed that grinding or drilling products containing encapsulated chrysotile resulted in exposures to chrysotile fibers far below the OSHA permissible exposure limit and the cancer no observed adverse effect level. Studies of other craftsmen who often work in the vicinity of electricians, such as insulators, reported asbestos (including amphibole) exposures that were relatively high. Overall, the evidence does not indicate that exposure to chrysotile in electrical products causes mesothelioma or lung cancer in electricians. Rather, the most likely cause of lung cancer in electricians is smoking, and the most likely cause of mesothelioma is exposure to amphibole asbestos as a result of renovation/demolition work or working in the proximity of other skilled craftsmen.     

Is there a problem with the status quo? Debating the need for standalone ethical guidelines for research with people who use alcohol and other drugs

In 2011, the Australian National Health and Medical Research Council (NHMRC) initiated an inquiry to determine whether there is a need for expanded ethical guidance in the form of a discrete guidance document for alcohol and other drug (AOD) research. An issues paper was developed to frame the inquiry. AOD researchers, Human Research Ethics Committees and others were invited to discuss whether there are distinctive ethical issues facing researchers and Human Research Ethics Committees in the AOD setting. Based on the public submissions, the NHMRC recommended that no AOD research‐specific guidance is required. The inquiry and the NHMRC decision were not widely publicized, and we feel there is a need for further discussion. In order to do so, we have analysed the public inquiry submissions and described the central themes. Few submissions in the inquiry explicitly agreed AOD research warrants a specific guidance framework. Most were concerned that the NHMRC issues paper unfairly targeted people who use drugs as complex research participants. The inquiry highlights tensions around research governance and ethics review boards dealing with illicit and stigmatised behaviours. While we agree that a specific guidance framework for AOD research is not needed and could potentially be harmful and restrictive, we are concerned that the wholesale rejection of a guidance framework has closed the door to much needed debate. There remains, we argue, a need for alternative strategies and tools to support ethical research, inform and streamline institutional ethics approval, and engage and protect participants. [Olsen A, Mooney‐Somers J. Is there a problem with the status quo? Debating the need for standalone ethical guidelines for research with people who use AODs. Drug Alcohol Rev 2014;33:637‐642]     

Key challenges in providing services to people who use drugs: The perspectives of people working in emergency departments and shelters in Atlantic Canada

Aims: Many people who use drugs (PWUD) have multiple health and social needs, and research suggests that this population is increasingly accessing emergency departments (EDs) and shelters for health care and housing. This qualitative study explored the practices of those working in EDs and shelters when providing services to PWUD, with a particular focus on key challenges in service provision. Methods: EDs and shelters were conceptualized as ‘micro environments’ with various components (i.e. social, physical and resource). One-on-one interviews were conducted with 57 individuals working in EDs and shelters in Atlantic Canada. Findings: The social, physical and resource environments within some EDs and shelters are key forces in shaping the challenges facing those providing services. For example, the social environments within these settings are focused on acute health care in the case of EDs, and housing in the case of shelters. These mandates do not encompass the complex needs of many PWUD. Resource issues within the wider community (e.g. limited drug treatment spaces) further contribute to the challenges. Conclusions: Structural issues, internal and external to EDs and shelters need to be addressed to reduce the challenges facing many who work in these settings when providing services to PWUD.