Texture Optimization of Water‐in‐Oil Emulsions

The aim of this research is to demonstrate the effect of variations in certain parameters of the oily phase (OP) in water‐in‐oil (W/O) emulsions on rheological and texture properties of finished products. The formulated emulsions were selected according to an optimal experimental procedure. The applied variations were nature of the OP, its volume fraction, the hydrophilic‐lipophilic balance (HLB) value, and the surfactant proportion. Results are presented for the followed tests carried out on the emulsions: texture analysis, rheology, and particle size analysis. The oils used in the study were sweet almond oil, liquid paraffin, maize oil, cyclomethicone, dimethicone, and wheat germ oil. The resulting data demonstrate a notable influence of the volume fraction oil on hardness, viscosity, adhesiveness, and cohesiveness of W/O emulsions. Emulsion hardness and viscosity increased as the OP percentage increased; this effect being even more pronounced for the vegetable oils. In contrast, emulsion adhesiveness and cohesiveness decreased as the volume fraction oil increased. The HLB value of the surfactant mixture of the emulsion also influenced hardness, adhesiveness, and elasticity, increasing or decreasing as HLB value did.     

Pro‐cognitive activity in rats of 3‐furan‐2‐yl‐N‐p‐tolyl‐acrylamide,a positive allosteric modulator of the α7 nicotinic acetylcholine receptor

Background and Purpose

α7 nicotinic acetylcholine receptors (α7 nAChRs) may represent useful targets for cognitive improvement. The aim of this study is to compare the pro‐cognitive activity of selective α7‐nAChR ligands, including the partial agonists, DMXBA and A‐582941, as well as the positive allosteric modulator, 3‐furan‐2‐yl‐N‐p‐tolyl‐acrylamide (PAM‐2).

Experimental Approach

The attentional set‐shifting task (ASST) and the novel object recognition task (NORT) in rats, were used to evaluate the pro‐cognitive activity of each ligand [i.e., PAM‐2 (0.5, 1.0, and 2.0 mg·kg⁻¹), DMXBA and A‐582941 (0.3 and 1.0 mg·kg⁻¹)], in the absence and presence of methyllycaconitine (MLA), a selective competitive antagonist. To determine potential drug interactions, an inactive dose of PAM‐2 (0.5 mg·kg⁻¹) was co‐injected with inactive doses of either agonist ‐ DMXBA: 0.1 (NORT); 0.3 mg·kg⁻¹ (ASST) or A‐582941: 0.1 mg·kg⁻¹.

Key Results

PAM‐2, DMXBA, and A‐582941 improved cognition in a MLA‐dependent manner, indicating that the observed activities are mediated by α7 nAChRs. Interestingly, the co‐injection of inactive doses of PAM‐2 and DMXBA or A‐582941 also improved cognition, suggesting drug interactions. Moreover, PAM‐2 reversed the scopolamine‐induced NORT deficit. The electrophysiological results also support the view that PAM‐2 potentiates the α7 nAChR currents elicited by a fixed concentration (3 μM) of DMXBA with apparent EC₅₀ = 34 ± 3 μM and E_max = 225 ± 5 %.

Conclusions and Implications

Our results support the view that α7 nAChRs are involved in cognition processes and that PAM‐2 is a novel promising candidate for the treatment of cognitive disorders.

Abbreviations

α7 nAChR

nicotinic acetylcholine receptor with α7 subunit

AD

Alzheimer''s disease

apparent EC₅₀

enhancement potency

ASST

attentional set‐shifting task

CD

compound discrimination

DI

discrimination index

E

exploration time

ED

extra‐dimensional

E_max

ligand efficacy

ID

intra‐dimensional

ITI

inter‐trial interval

MLA

methyllycaconitine

NORT

novel object recognition task

n_H

Hill coefficient

PAM

positive allosteric modulator

PAM‐2

3‐furan‐2‐yl‐N‐p‐tolyl‐acrylamide

Rev

reversal of discrimination

SD

simple discrimination

T1

familiarisation trial

T2

retention trial

     

Intravesical delivery of 5‐aminolevulinic acid from water‐in‐oil nano/submicron‐emulsion systems

The present work reports on the development of water‐in‐oil (w/o) emulsions for the intravesical administration of 5‐aminolevulinic acid (ALA). The physicochemical properties of droplet size, zeta potential, and viscosity of the emulsions are characterized and the ability of the emulsions to release ALA following in vitro application is tested. The delivery systems are administered intravesically for 1 and 3 h in rats to examine the drug accumulation in bladder tissue. The mean size and zeta potential of the emulsions are 50–200 nm and ?3 to ?14 mV, respectively. The loading of ALA into the emulsions resulted in a slower and sustained release. The release extent was found to be inversely related to the droplet size of the emulsions. The emulsions did not increase the drug permeation into tissues during short exposure duration (1 h). When the dwell time was extended to 3 h, the systems showed a 2.7‐fold increase in the ALA concentration in the bladder wall. Images of confocal laser scanning microscopy demonstrated a higher and deeper fluorescence signal, with emulsion administration, as compared to the aqueous control. Intravesical emulsion delivery provides a significant advantage for drugs targeting bladder tissues. © 2009 Wiley‐Liss, Inc. and the American Pharmacists Association J Pharm Sci 99: 2375–2385, 2010     

Protective Effect of N‐Acetylcysteine Against Arsenic‐Induced Depletion In Vivo of Carbohydrate

N‐acetylcysteine (NAC), a synthetic aminothiol, possesses antioxidative and cytoprotective properties. The present study evaluates the effect of NAC supplementation on arsenic‐induced depletion in vivo of carbohydrates. Arsenic (as sodium arsenite) treatment (i.p.) of male Wistar rats (120–140 g b.w.) at a dose of 5.55 mg/kg body weight (35% of LD₅₀) per day for a period of 30 days produced a significant decrease in blood glucose level (hypoglycemia) and a fall in liver glycogen and pyruvic acid contents. The free amino acid nitrogen content of liver increased while that of kidney decreased after arsenic treatment. Arsenic also enhanced the liver lactate dehydrogenase activity whereas glucose 6‐phosphatase activity in both liver and kidney decreased significantly following arsenic treatment. Transaminase activities in liver and kidney were not significantly altered except the glutamate–pyruvate transaminase activity that was reduced in kidney after arsenic treatment. Oral administration of NAC (163.2 mg/kg/day) for last 7 days of treatment prevented the arsenic‐induced hypoglycemia and glycogenolytic effects to an appreciable extent. There was also recovery of liver pyruvic acid as well as liver and kidney free amino acid nitrogen content after NAC supplementation. Arsenic‐induced alteration of glucose 6‐phosphatase activity in both liver and kidney was also counteracted by NAC. It is suggested that carbohydrate depletion in vivo due to exposure to arsenic can be counteracted by NAC supplementation.     

A comparison of medical symptoms reported by cocaine‐, opiate‐, and alcohol‐dependent patients

Substance abuse is frequently associated with adverse medical consequences. The differences in medical symptoms reported by 101 alcohol‐, 113 cocaine‐, and 107 opiate‐dependent individuals receiving outpatient treatment were studied using a 134‐item questionnaire (MILCOM). Data analysis revealed interesting and unexpected findings, with cocaine patients reporting the fewest total symptoms among the three groups. Moreover, cocaine patients reported significantly fewer CNS and musculo‐skeletal symptoms compared to both alcohol and opiate patients and significantly fewer GI and urinary symptoms than the alcohol but not the opiate patients. In addition, there were sex‐ and race‐related differences in the pattern of symptoms reported. Women reported significantly more CVS, mood, nose/throat, CNS, skin, and GI symptoms than men. Similarly, Caucasians reported significantly more mood, CNS, nose/throat, head/neck, musculoskeletal, and GI symptoms than African‐Americans. The study highlights the influence of drug of choice, gender, and race on medical needs of substance‐abusing persons.     

Protective effect of 23‐hydroxybetulinic acid on doxorubicin‐induced cardiotoxicity: a correlation with the inhibition of carbonyl reductase‐mediated metabolism

Background and Purpose

The clinical use of doxorubicin, an effective anticancer drug, is severely hampered by its cardiotoxicity. 23‐Hydroxybetulinic acid (23‐HBA), isolated from P ulsatilla chinensis, enhances the anticancer effect of doxorubicin while simultaneously reducing its cardiac toxicity, but does not affect the concentration of doxorubicin in the plasma and heart. As the metabolite doxorubicinol is more potent than doxorubicin at inducing cardiac toxicity, in the present study we aimed to clarify the role of doxorubicinol in the protective effect of 23‐HBA.

Experimental Approach

Doxorubicin was administered to mice for two weeks in the presence or absence of 23‐HBA. The heart pathology, function, myocardial enzymes and accumulation of doxorubicin and doxorubicinol were then analysed. A cellular pharmacokinetic study of doxorubicin and doxorubicinol, carbonyl reductase 1 (CBR1) interference and molecular docking was performed in vitro.

Key Results

23‐HBA alleviated the doxorubicin‐induced cardiotoxicity in mice, and this was accompanied by inhibition of the metabolism of doxorubicin and reduced accumulation of doxorubicinol selectively in hearts. In H9c2 cells, the protective effect of 23‐HBA was shown to be closely associated with a decreased rate and extent of accumulation of doxorubicinol in mitochondria and nuclei. siRNA and docking analysis demonstrated that CBR1 has a crucial role in doxorubicin‐mediated cardiotoxicity and 23‐HBA inhibits this metabolic pathway.

Conclusions and Implications

Inhibition of CBR‐mediated doxorubicin metabolism might be one of the protective mechanisms of 23‐HBA against doxorubicin‐induced cardiotoxicity. The present study provides a new research strategy guided by pharmacokinetic theory to elucidate the mechanism of drugs with unknown targets.

Linked Articles

This article is part of a themed section on Chinese Innovation in Cardiovascular Drug Discovery. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2015.172.issue-23

Abbreviations

23‐HBA

23‐hydroxybetulinic acid

AST

aspartate aminotransferase

CBR1

carbonyl reductase 1

CMC

carboxymethyl cellulose

CK

creatine kinase

CK‐MD

creatine kinase isoenzyme

EF

ejection fraction

FS

fractional shortening

i.g

intragastrically

LV

left ventricle

MDR

multidrug resistance

TCM

traditional Chinese medicine

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Prevention and treatment of glucocorticoid‐induced osteoporosis

Glucocorticoidinduced osteoporosis is a common clinical problem. This review briefly summarizes the pathogenesis of this disorder. All relevant studies on the prevention and treatment of glucocorticoidinduced osteoporosis are discussed more in detail. As the results of these studies are inconclusive, a proposal for a practical approach of the individual patient is formulated.     

In Vitro Regioselective Stability of β‐1‐O‐ and 2‐O‐Acyl Glucuronides of Naproxen and Their Covalent Binding to Human Serum Albumin

β‐1‐O‐ (NAG) and 2‐O‐glucuronides (2‐isomer) of (S)‐naproxen (NA) were prepared to determine which positional isomer‐(s) of the acyl glucuronide of NA is responsible for forming covalent adducts with human serum albumin (HSA). Their comparative stability and covalent binding adduct formation with HSA were investigated at pH 7.4 and at 37 °C. NA and its acyl glucuronides were simultaneously determined by HPLC. Three positional isomers were formed successively after incubation of NAG in the buffer only. However, when NAG was incubated with HSA (30 mg/mL), isomers other than the 2‐isomer were formed in little or negligible quantities. In HSA solution, NAG (k_d = 2.08 ± 0.08 h⁻¹) was four times less stable than 2‐isomer (k_d = 0.51 ± 0.02 h⁻¹). NAG was degraded by hydrolysis (k_hyd = 1.01 ± 0.10 h⁻¹) and isomerization (k_iso = 1.07 ± 0.07 h⁻¹) to the same extent; however, hydrolysis was predominant for the 2‐isomer (k_d = 0.51 ± 0.02 h⁻¹). The incubation of both NAG and 2‐isomer with HSA led to the formation of a covalent adduct; however, the adduct formation from the 2‐isomer proceeded more slowly than that from NAG. The present results suggest that the covalent binding of NA to HSA via its acyl glucuronides proceeds through both transacylation (direct nucleophilic displacement) and glycation mechanisms; NAG rapidly forms an adduct that may be unstable, and the protein adduct from the 2‐O‐acyl glucuronide is as important for the covalent binding as those from the 1‐O‐acyl glucuronides.     

Can Controlled Ice Nucleation Improve Freeze‐Drying of Highly‐Concentrated Protein Formulations?

The aim of this study was to investigate if controlled ice nucleation with our previouly published method is applicable to highly‐concentrated protein formulations of bovine serum albumin (100 mg/ml and 193.9 mg/ml) and a monoclonal antibody (161.2 mg/ml) and if positive effects on primary drying time as well as reconstitution times can be achieved. We observed that for both proteins, ice nucleation at a product temperature of ?5 °C significantly reduced primary drying time. Furthermore, reconstitution times of the lyophilized cakes could be shortened, especially for the monoclonal antibody formulation with a reconstitution time of 5 minutes instead of 15 minutes. © 2013 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 102:3915–3919, 2013     

Impacts of Compression on Crystallization Behavior of Freeze‐Dried Amorphous Sucrose

An amorphous matrix comprised of sugar molecules is used as excipient and stabilizing agent for labile ingredients in the pharmaceutical industry. The amorphous sugar matrix is often compressed into a tablet form to reduce the volume and improve handling. Herein, the effect of compression on the crystallization behavior of an amorphous sucrose matrix was investigated. Amorphous sucrose samples were prepared by freeze‐drying and compressed under different conditions, followed by analyses by differential scanning calorimetry, isothermal crystallization tests, X‐ray powder diffractometry, Fourier transform infrared spectroscopy (FTIR), and gas pycnometry. The compressed sample had a lower crystallization temperature and a shorter induction period for isothermal crystallization, indicating that compression facilitates the formation of the critical nucleus of a sucrose crystal. Based on FTIR and molecular dynamics simulation results, the conformational distortion of sucrose molecules due to the compression appears to contribute to the increase in the free energy of the system, which leads to the facilitation of critical nucleus formation. An isothermal crystallization test indicated an increase in the growth rate of sucrose crystals by the compression. This can be attributed to the transformation of the microstructure from porous to nonporous, as the result of compression. © 2009 Wiley‐Liss, Inc. and the American Pharmacists Association J Pharm Sci 99: 1452–1463, 2010     

Genotyping of the arylamine N‐acetyltransferase polymorphism in the prediction of idiosyncratic reactions to trimethoprim‐sulfamethoxazole in infants.

The pathogenesis of hypersensitivity to trimethoprimsulfamethoxazole (TMPSMX) is supposed to be associated with the slow acetylation phenotype. This pharmacogenetic defect is associated with the mutations of the arylamine Nacetyltransferase (NAT2) encoding gene. The aim of the study was to compare the usefulness of the acetylation phenotype and NAT2 coding genotype in the prediction of idiosyncratic reaction to Cotrimoxazole in infants. The study was carried out in the group of 20 infants, aged 212 months (mean age 6.3 months) treated with Cotrimoxazole, administered at 100 mg/kg b.w./24 h doses. In seven children (35%) no adverse effects of the treatment have been observed, whereas in 13 (65%) children various adverse effects occurred as a result of the therapy, such as rash (4 children), granulocytopenia with anemization (5 children) or liver impairment (4 children). The acetylation phenotype of each child was determined on the basis of urine of Nacetyl isoniazid/isoniazid ratio, after ingestion of isoniazid as a model drug. Furthermore we used polymerase chain reaction (PCR) followed by the analysis of restriction fragments length polymorphism (RFLP) technique to identify the known mutant alleles of the NAT2 gene. It has been presumed that the genotype determining fast acetylation contains at least one of wildtype allele. No correlation has been found between the observed adverse effects of Cotrimoxazole and age, gender and acetylation phenotype. However, it has been demonstrated that the risk of adverse effects of Cotrimoxazole is considerably higher in children with mutations of the NAT2 encoding gene. The comparison of the results from PCRRFLP genotyping with phenotyping suggested that in infants, the NAT2 genotype rather than phenotype provides the basis for the detection of hypersensitivity to TMPSMX.     

High‐density lipoprotein inhibits human M1 macrophage polarization through redistribution of caveolin‐1

Background and Purpose

Monocyte‐derived macrophages are critical in the development of atherosclerosis and can adopt a wide range of functional phenotypes depending on their surrounding milieu. High‐density lipoproteins (HDLs) have many cardio‐protective properties including potent anti‐inflammatory effects. We investigated the effects of HDL on human macrophage phenotype and the mechanisms by which these occur.

Experimental Approach

Human blood monocytes were differentiated into macrophages in the presence or absence of HDL and were then induced to either an inflammatory macrophage (M1) or anti‐inflammatory macrophage (M2) phenotype using LPS and IFN‐γ or IL‐4, respectively.

Key Results

HDL inhibited the induction of macrophages to an M1‐phenotype, as evidenced by a decrease in the expression of M1‐specific cell surface markers CD192 and CD64, as well as M1‐associated inflammatory genes TNF‐α, IL‐6 and MCP‐1 (CCL2). HDL also inhibited M1 function by reducing the production of ROS. In contrast, HDL had no effect on macrophage induction to the M2‐phenotype. Similarly, methyl‐β‐cyclodextrin, a non‐specific cholesterol acceptor also suppressed the induction of M1 suggesting that cholesterol efflux is important in this process. Furthermore, HDL decreased membrane caveolin‐1 in M1 macrophages. We confirmed that caveolin‐1 is required for HDL to inhibit M1 induction as bone marrow‐derived macrophages from caveolin‐1 knockout mice continued to polarize into M1‐phenotype despite the presence of HDL. Moreover, HDL decreased ERK1/2 and STAT3 phosphorylation in M1 macrophages.

Conclusions and Implications

We concluded that HDL reduces the induction of macrophages to the inflammatory M1‐phenotype via redistribution of caveolin‐1, preventing the activation of ERK1/2 and STAT3.

Linked Articles

This article is part of a themed section on Inflammation: maladies, models, mechanisms and molecules. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2016.173.issue-4

Abbreviations

BMDMs

bone marrow‐derived macrophages

Cav‐1^−/−

caveolin‐1 knockout

HDL

high‐density lipoprotein

MβCD

methyl‐beta‐cyclodextrin

M1

inflammatory macrophage

M2

anti‐inflammatory macrophage

WT

wild‐type

     

Pharmacodynamics,pharmacokinetics and safety of GSK2190915, a novel oral anti‐inflammatory 5‐lipoxygenase‐activating protein inhibitor

Aim

To assess the pharmacokinetics, pharmacodynamics, safety and tolerability of the 5‐lipoxygenase‐activating protein inhibitor, GSK2190915, after oral dosing in two independent phase I studies, one in Western European and one in Japanese subjects, utilizing different formulations.

Method

Western European subjects received single (50–1000 mg) or multiple (10–450 mg) oral doses of GSK2190915 or placebo in a dose‐escalating manner. Japanese subjects received three of four GSK2190915 doses (10–200 mg) plus placebo once in a four period crossover design. Blood samples were collected for GSK2190915 concentrations and blood and urine were collected to measure leukotriene B₄ and leukotriene E₄, respectively, as pharmacodynamic markers of drug activity.

Results

There was no clear difference in adverse events between placebo and active drug‐treated subjects in either study. Maximum plasma concentrations of GSK2190915 and area under the curve increased in a dose‐related manner and mean half‐life values ranged from 16–34 h. Dose‐dependent inhibition of blood leukotriene B₄ production was observed and near complete inhibition of urinary leukotriene E₄ excretion was shown at all doses except the lowest dose. The EC₅₀ values for inhibition of LTB₄ were 85 nm and 89 nm in the Western European and Japanese studies, respectively.

Conclusion

GSK2190915 is well‐tolerated with pharmacokinetics and pharmacodynamics in Western European and Japanese subjects that support once daily dosing for 24 h inhibition of leukotrienes. Doses of ≥50 mg show near complete inhibition of urinary leukotriene E₄ at 24 h post‐dose, whereas doses of ≥150 mg are required for 24 h inhibition of blood LTB₄.     

Lyophilised liposome‐based formulations of α‐tocopheryl succinate: Preparation and physico‐chemical characterisation

α‐Tocopheryl succinate (α‐TOS) is a semisynthetic analogue of α‐tocopherol with selective toxicity to the cancer cells and anticancer activity in vivo. Yet, no suitable formulation of α‐TOS for medical application has been reported. Various formulations, for example, solutions in organic solvents, oil emulsions and vesicules prepared by spontaneous vesiculation, polyethylene glycol conjugates and liposomes of various compositions have been tested. We developed and characterised a stable lyophilised liposome‐based α‐TOS formulation. α‐TOS (15 mol%) was incorporated into large oligolamellar vesicles (OLVs) composed of soy phosphatidylcholine (SPC) by the method of lipid film hydration followed by extrusion through polycarbonate filters. Stabilised liposomal formulation was prepared by lyophilisation in the presence of sucrose (molar ratio lipid/sucrose, 1:5). The size distribution of the liposomes (130–140 nm, polydispersity index 0.14) as well as the stable lipid and α‐TOS contents were preserved during storage in the lyophilised form at 2–8°C for at least 6 months. The data indicate good physical and chemical stability of the lyophilised preparation of α‐TOS liposomes that can be used in clinical medicine. © 2009 Wiley‐Liss, Inc. and the American Pharmacists Association J Pharm Sci 99: 2434–2443, 2010     

Regulator of G‐protein signalling 5 protects against atherosclerosis in apolipoprotein E‐deficient mice

Background and Purpose

Atherosclerosis is a chronic inflammatory disease, in which ‘vulnerable plaques’ have been recognized as the underlying risk factor for coronary disease. Regulator of G‐protein signalling (RGS) 5 controls endothelial cell function and inflammation. In this study, we explored the effect of RGS5 on atherosclerosis and the potential underlying mechanisms.

Experimental Approach

RGS5^−/− apolipoprotein E (ApoE)^−/− and ApoE ^−/− littermates were fed a high‐fat diet for 28 weeks. Total aorta surface and lipid accumulation were measured by Oil Red O staining and haematoxylin–eosin staining was used to analyse the morphology of atherosclerotic lesions. Inflammatory cell infiltration and general inflammatory mediators were examined by immunofluorescence staining. Apoptotic endothelial cells and macrophages were assayed with TUNEL. Expression of RGS5and adhesion molecules, and ERK1/2 phosphorylation were evaluated by co‐staining with CD31. Expression of mRNA and protein were determined by quantitative real‐time PCR and Western blotting respectively.

Key Results

Atherosclerotic phenotypes were significantly accelerated in RGS5^−/− ApoE ^−/− mice, as indicated by increased inflammatory mediator expression and apoptosis of endothelial cells and macrophages. RGS5 deficiency enhanced instability of vulnerable plaques by increasing infiltration of macrophages in parallel with the accumulation of lipids, and decreased smooth muscle cell and collagen content. Mechanistically, increased activation of NF‐κB and MAPK/ERK 1/2 could be responsible for the accelerated development of atherosclerosis in RGS5‐deficient mice.

Conclusions and Implications

RGS5 deletion accelerated development of atherosclerosis and decreased the stability of atherosclerotic plaques partly through activating NF‐κB and the MEK‐ERK1/2 signalling pathways.

Linked Articles

This article is part of a themed section on Chinese Innovation in Cardiovascular Drug Discovery. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2015.172.issue-23

Abbreviations

ApoE

apolipoprotein E

CHD

coronary heart disease

H&E

haematoxylin‐eosin

ICAM‐1

intercellular adhesion molecue‐1

LDL

low‐density lipoprotein

MEK

MAPK/ERK kinase

RGS

regulator of G‐protein signalling

SMC

smooth muscle cell

VCAM‐1

vascular cell adhesion molecule‐1

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Antisense‐mediated reduction of proprotein convertase subtilisin/kexin type 9 (PCSK9): a first‐in‐human randomized,placebo‐controlled trial

AimsLDL‐receptor expression is inhibited by the protease proprotein convertase subtilisin/kexin type 9 (PCSK9), which is considered a pharmacological target to reduce LDL‐C concentrations in hypercholesterolaemic patients. We performed a first‐in‐human trial with SPC5001, a locked nucleic acid antisense inhibitor of PCSK9.MethodsIn this randomized, placebo‐controlled trial, 24 healthy volunteers received three weekly subcutaneous administrations of SPC5001 (0.5, 1.5 or 5 mg kg^–1) or placebo (SPC5001 : placebo ratio 6 : 2). End points were safety/tolerability, pharmacokinetics and efficacy of SPC5001.ResultsSPC5001 plasma exposure (AUC(0,24 h)) increased more than dose‐proportionally. At 5 mg kg^–1, SPC5001 decreased target protein PCSK9 (day 15 to day 35: −49% vs. placebo, P < 0.0001), resulting in a reduction in LDL‐C concentrations (maximal estimated difference at day 28 compared with placebo −0.72 mmol l^–1, 95% confidence interval − 1.24, −0.16 mmol l^–1; P < 0.01). SPC5001 treatment (5 mg kg^–1) also decreased ApoB (P = 0.04) and increased ApoA1 (P = 0.05). SPC5001 administration dose‐dependently induced mild to moderate injection site reactions in 44% of the subjects, and transient increases in serum creatinine of ≥20 μmol l^–1 (15%) over baseline with signs of renal tubular toxicity in four out of six subjects at the highest dose level. One subject developed biopsy‐proven acute tubular necrosis.ConclusionsSPC5001 treatment dose‐dependently inhibited PCSK9 and decreased LDL‐C concentrations, demonstrating human proof‐of‐pharmacology. However, SPC5001 caused mild to moderate injection site reactions and renal tubular toxicity, and clinical development of SPC5001 was terminated. Our findings underline the need for better understanding of the molecular mechanisms behind the side effects of compounds such as SPC5001, and for sensitive and relevant renal toxicity monitoring in future oligonucleotide studies.