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Assay and stability-indicating micellar electrokinetic chromatography method for the simultaneous determination of valacyclovir, acyclovir and their major impurity guanine in pharmaceutical formulations

Al Azzam KM, Saad B, Makahleah A, Aboul-Enein HY, Elbashir AA

Biomed Chromatogr, 2010 May;24(5):535-43.
PMID: 19739243 DOI: 10.1002/bmc.1323

A micellar electrokinetic chromatography (MEKC) method for the simultaneous determination of the antiviral drugs acyclovir and valacyclovir and their major impurity, guanine, was developed. The influences of several factors (surfactant and buffer concentration, pH, applied voltage, capillary temperature and injection time) were studied. Using tyramine hydrochloride as internal standard, the analytes were all separated in about 4 min. The separation was carried out in reversed polarity mode at 28 degrees C, 25 kV and using hydrodynamic injection (15 s). The separation was effected in a fused-silica capillary 100 microm x 56 cm and a background electrolyte of 20 mM citric acid-1 M Tris solution (pH 2.75), containing 125 mM sodium dodecyl sulphate and detection at 254 nm. The method was validated with respect to linearity, limit of detection and quantification, accuracy, precision and selectivity. Calibration curves were linear over the range 0.1-1 microg/mL (guanine) and from 0.1 to 120 microg/mL for both valacyclovir and acyclovir. The relative standard deviations of intra- and inter-day migration times and corrected peak areas were less than 5.0%. The proposed method was successfully applied to the determination of the analytes in tablets and creams. From the previous study it is concluded that the stability-indicating method developed for acyclovir and valacyclovir can be used for analysis of the drug in various stability samples.

Matched MeSH terms: Valine/analogs & derivatives*
Fulltext A comparison of valsartan and perindopril in the treatment of essential hypertension in the Malaysian population

Bavanandan S, Morad Z, Ismail O, Chandran A, Thayaparan T, Singaraveloo M

Med J Malaysia, 2005 Jun;60(2):158-62.
PMID: 16114156 MyJurnal

This study was conducted to determine the tolerability and efficacy of valsartan (DIOVAN) compared to perindopril (COVERSYL) in Malaysian patients with mild to moderate hypertension. Two hundred and fifty adult Malaysian patients with a mean sitting diastolic blood pressure of more than 95 mmHg and less than 115 mmHg after a 14 day washout period were randomized to receive either valsartan 80 mg once daily (n=125) or perindopril 4 mg daily (n=125) for eight weeks. The primary end point for efficacy was the change in mean sitting systolic and diastolic blood pressure (SiSBP and SiDBP). The primary criteria for evaluation of tolerability was the incidence of adverse events. There were no significant differences between the two groups with respect to sex, age, weight, baseline sitting and standing systolic and diastolic blood pressure. At 0, 4 and 8 weeks the mean SiDBP in the valsartan group were 101.4, 92.8 and 91.0 mmHg respectively. The corresponding BP for the perindopril treated group was 102.6, 93.8 and 93.2 mmHg. (95% CI -1.39 to +3.27). There were no significant differences in the mean BP measurements between the valsartan and perindopril group at 0, 4 and 8 weeks. In each group there were significant differences between the BP at 4 and 8 weeks compared to baseline. A similar pattern was seen with SiSBP. At 4 weeks 28.7% of the valsartan and 25% of the perindopril group had their BP normalized (SiDBP <90 mmHg) The percentages of patients who responded (SiDBP reduction >10 mmHg but SiDBP >90 mmHg) were 21.3 in the valsartan group and 20.8 in the perindopril group. At 8 weeks, 31.1% of the valsartan group and 30.8% of the perindopril group had their BP normalized. The response rate was 27% and 22.5% for valsartan and perindopril respectively. The major adverse event was cough which occurred in 18 patients (14.4%) in the perindopril and 1 (0.8%) in the valsartan group at 4 weeks. At 8 weeks the figures were 24 (19.2%) and 2 (1.6%) respectively. The results indicate that Valsartan is safe and efficacious in the treatment of mild to moderate hypertension. It is equally efficacious to Perindopril and not associated with any major adverse event. It has a better tolerability profile with respect to dry cough.

Matched MeSH terms: Valine/analogs & derivatives*
Effect of angiotensin II on pulse wave velocity in humans is mediated through angiotensin II type 1 (AT(1)) receptors

Rehman A, Rahman AR, Rasool AH

J Hum Hypertens, 2002 Apr;16(4):261-6.
PMID: 11967720

The objective of this study was to examine the effect of angiotensin II (Ang II) and angiotensin II type 1 (AT(1)) receptor blockade on pulse wave velocity (PWV) in healthy humans. We studied nine young male volunteers in a double-blind randomised crossover design. Carotid-femoral PWV (an index of arterial stiffness) was measured by using a Complior machine. Subjects were previously treated for 3 days with once-daily dose of either a placebo or valsartan 80 mg. On the third day, they were infused with either placebo or 5 ng/kg/min of Ang II over 30 min. Subjects thus received placebo capsule + placebo infusion (P), valsartan + placebo infusion (V), placebo + Ang II infusion (A), and valsartan + Ang II infusion (VA) combinations. Heart rate (HR), blood pressure and PWV were recorded at baseline and then every 10 min during infusion and once after the end of infusion. There were significant increases in systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial pressure (MAP) with A compared with P (P = 0.002, P = 0.002, P = 0.001 respectively). These rises in blood pressure were completely blocked by valsartan. A significant rise in PWV by A was seen compared with P (8.38 +/- 0.24 vs 7.48 +/- 0.24 m/sec, P = 0.013) and was completely blocked by valsartan; VA compared with P (7.27 +/- 0.24 vs 7.48 +/- 0.24 m/sec, P = NS). Multiple linear regression analysis showed that blockade of Ang II induced increase in blood pressure by valsartan contributed to only 30% of the total reduction in Ang II induced rise in PWV (R(2) = 0.306). The conclusions were that valsartan completely blocks the effect of Ang II on PWV. The effect of Ang II on PWV is mediated through AT(1)receptors. Reduction in PWV by Ang II antagonist is not fully explained by its pressure lowering effect of Ang II and may be partially independent of its effect on blood pressure.

Matched MeSH terms: Valine/analogs & derivatives
Real-life safety and effectiveness of amlodipine/valsartan combination in the treatment of hypertension

Chazova IE, Dongre N, Vigdorchik AV

Adv Ther, 2011 Feb;28(2):134-49.
PMID: 21240661 DOI: 10.1007/s12325-010-0099-1

The aim of our study was to evaluate the safety and effectiveness of the free combination of amlodipine/valsartan in patients with arterial hypertension in a real-life setting.

Matched MeSH terms: Valine/analogs & derivatives*
Arginase activity in a murine macrophage cell line (RAW264.7) stimulated with lipopolysaccharide from Actinobacillus actinomycetemcomitans

Sosroseno W, Musa M, Ravichandran M, Fikri Ibrahim M, Bird PS, Seymour GJ

Oral Microbiol. Immunol., 2006 Jun;21(3):145-50.
PMID: 16626370

The aim of the present study was to determine whether or not lipopolysaccharide from Actinobacillus actinomycetemcomitans could stimulate arginase activity in a murine macrophage cell line (RAW264.7 cells).

Matched MeSH terms: Valine/analogs & derivatives
Fulltext Efficacy and safety of ravidasvir plus sofosbuvir in patients with chronic hepatitis C infection without cirrhosis or with compensated cirrhosis (STORM-C-1): interim analysis of a two-stage, open-label, multicentre, single arm, phase 2/3 trial

Andrieux-Meyer I, Tan SS, Thanprasertsuk S, Salvadori N, Menétrey C, Simon F, et al.

Lancet Gastroenterol Hepatol, 2021 Jun;6(6):448-458.
PMID: 33865507 DOI: 10.1016/S2468-1253(21)00031-5

BACKGROUND: In low-income and middle-income countries, affordable direct-acting antivirals are urgently needed to treat hepatitis C virus (HCV) infection. The combination of ravidasvir, a pangenotypic non-structural protein 5A (NS5A) inhibitor, and sofosbuvir has shown efficacy and safety in patients with chronic HCV genotype 4 infection. STORM-C-1 trial aimed to assess the efficacy and safety of ravidasvir plus sofosbuvir in a diverse population of adults chronically infected with HCV.
METHODS: STORM-C-1 is a two-stage, open-label, phase 2/3 single-arm clinical trial in six public academic and non-academic centres in Malaysia and four public academic and non-academic centres in Thailand. Patients with HCV with compensated cirrhosis (Metavir F4 and Child-Turcotte-Pugh class A) or without cirrhosis (Metavir F0-3) aged 18-69 years were eligible to participate, regardless of HCV genotype, HIV infection status, previous interferon-based HCV treatment, or source of HCV infection. Once daily ravidasvir (200 mg) and sofosbuvir (400 mg) were prescribed for 12 weeks for patients without cirrhosis and for 24 weeks for those with cirrhosis. The primary endpoint was sustained virological response at 12 weeks after treatment (SVR12; defined as HCV RNA <12 IU/mL in Thailand and HCV RNA <15 IU/mL in Malaysia at 12 weeks after the end of treatment). This trial is registered with ClinicalTrials.gov, number NCT02961426, and the National Medical Research Register of Malaysia, NMRR-16-747-29183.
FINDINGS: Between Sept 14, 2016, and June 5, 2017, 301 patients were enrolled in stage one of STORM-C-1. 98 (33%) patients had genotype 1a infection, 27 (9%) had genotype 1b infection, two (1%) had genotype 2 infection, 158 (52%) had genotype 3 infection, and 16 (5%) had genotype 6 infection. 81 (27%) patients had compensated cirrhosis, 90 (30%) had HIV co-infection, and 99 (33%) had received previous interferon-based treatment. The most common treatment-emergent adverse events were pyrexia (35 [12%]), cough (26 [9%]), upper respiratory tract infection (23 [8%]), and headache (20 [7%]). There were no deaths or treatment discontinuations due to serious adverse events related to study drugs. Of the 300 patients included in the full analysis set, 291 (97%; 95% CI 94-99) had SVR12. Of note, SVR12 was reported in 78 (96%) of 81 patients with cirrhosis and 153 (97%) of 158 patients with genotype 3 infection, including 51 (96%) of 53 patients with cirrhosis. There was no difference in SVR12 rates by HIV co-infection or previous interferon treatment.
INTERPRETATION: In this first stage, ravidasvir plus sofosbuvir was effective and well tolerated in this diverse adult population of patients with chronic HCV infection. Ravidasvir plus sofosbuvir has the potential to provide an additional affordable, simple, and efficacious public health tool for large-scale implementation to eliminate HCV as a cause of morbidity and mortality.
FUNDING: National Science and Technology Development Agency, Thailand; Department of Disease Control, Ministry of Public Health, Thailand; Ministry of Health, Malaysia; UK Aid; Médecins Sans Frontières (MSF); MSF Transformational Investment Capacity; FIND; Pharmaniaga; Starr International Foundation; Foundation for Art, Research, Partnership and Education; and the Swiss Agency for Development and Cooperation.

Matched MeSH terms: Valine/analogs & derivatives*