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Research Article | Volume 14 Issue: 4 (Jul-Aug, 2024) | Pages 71 - 81
Comparative evaluation of different brands of sacubitril/valsartan for the presence of co-crystallization
 ,
 ,
1
Head, Department of Cardiology & Interventional Cardiology, PRS Hospital, Trivandrum, Kerala, India;
2
Director and Lead Consultant, Heart Rhythm Services & Cardiac pacing Division, Fortis Hospital Mohali, Punjab, India;
3
Principal Director & Chief of Cath Labs (Pan Max) Cardiac Sciences, Max Super Specialty Hospital, Saket, Delhi, India.
Under a Creative Commons license
Open Access
Received
May 20, 2024
Revised
June 13, 2024
Accepted
June 30, 2024
Published
July 14, 2024
Abstract

Background: Sacubitril/valsartan, marketed as Azmarda (manufactured by the innovator company) is a cocrystal consisting 6 sacubitril and valsartan molecules, along with sodium cations and water molecules. This formulation is considered a major mechanism of benefit of this molecule. This study was aimed to assess various brands of sacubitril/valsartan in the market for the presence of the cocrystal forms and compare them with Azmarda. a brand of sacubitril/valsartan manufactured by the innovator company.

Methods: The study involved analysis of various marketed products containing sacubitril/valsartan tablets, including Azmarda. Both the Azmarda and marketed products were characterized using differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD). Sodium content and dissolution studies were also performed .

Results: A total of 16 brands of marketed products including Azmarda were studied.  During DSC studies, unique melting pattern was observed in Azmarda, with exothermic peaks of sacubitril/valsartan detected at 140°C and 102°C, respectively. PXRD analysis revealed that none of the products exhibited the same crystal lattice as Azmarda. Azmarda, with a sodium level of 1.773%, was comparable to brand 2 (1.61%), brand 4 (1.73%), and brand 7 (1.58%). Azmarda demonstrated 64% release of sacubitril and 57% release of valsartan within 30 minutes in 0.1N HCl. Brand 7, brand 12, and brand 13 showed 52%, 57%, and 52% release of sacubitril, respectively, and 45%, 52%, and 48% release of valsartan, respectively, in 30 minutes.

Conclusion: The absence of identical crystal lattice structures, highlights absence of co-crystals in generic formulations. Such variations may impact the bioavailability and efficacy, emphasizing the importance of ensuring consistent and reliable therapeutic outcomes.

 

Keywords
INTRODUCTION

Sacubitril/valsartan represents a pioneering class of medications, combining neprilysin inhibition with angiotensin II receptor antagonism. This unique combination effectively enhances endogenous natriuretic peptides while inhibiting the renin–angiotensin-aldosterone system [1]. Sacubitril/valsartan is a cocrystal consisting of 6 sacubitril and 6 valsartan moieties in their anionic forms, 18 penta- and hexa-coordinated sodium cations, and 15 water molecules.

According to the PARADIGM-HF trial findings, sacubitril/valsartan demonstrated a significant advantage over enalapril in reducing cardiovascular mortality, heart failure hospitalization risk, heart failure symptoms, and physical limitations. The trial was prematurely stopped after a median follow-up of 27 months, revealing substantial advantages of sacubitril/valsartan [2]. The TRANSITION study further demonstrated the feasibility of achieving target doses within 10 weeks. This study revealed that initiating sacubitril/valsartan stabilized patients with heart failure with reduced ejection fraction (HFrEF) following an acute heart failure event, whether in the hospital or shortly after discharge [3].

Valsartan, classified as a Biopharmaceutical Classification System (BCS) Class II, exhibits low solubility and high permeability [4]. This classification suggests that bioavailability from oral dosage forms is dissolution rate limited. Sacubitril/valsartan are highly hygroscopic in nature and difficult to handle when used in amorphous (non-crystalline) form and can adversely affect it invitro and in vivo performance including storage concerns.  A drug's efficacy depends on various factors, including solubility, stability, dissolution rate, and hygroscopicity [5]. Ongoing research explores methods to enhance oral absorption for medications with low water solubility and/or limited permeability, with pharmaceutical cocrystals emerging as a promising tool for improving bioavailability [6].

As an emerging tool, pharmaceutical cocrystals can be utilized to modify the solubility, dissolution rate, and both the physical and chemical stability of drug substances, aiming to retain the drug's pharmacological effect without significant alteration [7].

 

The invention of the supramolecular complex, a cocrystal of sacubitril/valsartan, is a great boon to cardiovascular patients. In 2015, sacubitril/valsartan (Entresto, development code LCZ696) was approved by the U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA) as the first successful angiotensin receptor neprilysin inhibitor (ARNI) in the market [8]. The sacubitril/valsartan combination was developed by Novartis and marketed by JB Chemicals as Azmarda in India.  The polymorphic technology of Azmarda has been recognized and patented. This cocrystal formulation is the one that has been tried and proven effective in RCTs.  Many pharmaceutical companies have adopted alternative strategies to combine sacubitril/valsartan in their products, with different manufacturing process. One of these potential methods involves utilizing a fixed-dose combination (FDC) of sacubitril/valsartan.

Given the significance of the co-crystal form in sacubitril/valsartan tablets, this study aimed to assess various brands in the market for the presence of the co-crystal form, comparing them with the innovator product.

METHODS

Study design and material

 The study involved the analysis of various marketed products containing sacubitril/valsartan tablets, including Azmarda manufactured by innovator company. The sacubitril/valsartan sodium salt complex in cocrystal form was acquired from Ami Life Sciences. Solid-state forms were identified using X-ray powder diffraction. The solvents and reagents used for co-crystallization, such as isopropyl alcohol, hydrochloric acid (HCl), sodium phosphate buffer, sodium hydroxide, nitric acid, and hydrogen peroxide, were of analytical grade from Merck Limited. Double-distilled water or high-performance liquid chromatography (HPLC) grade water was used as needed.

 

Physical mixture preparation method

Sacubitril/valsartan were mixed in a defined 1:1 stoichiometric ratio. This mixture was prepared and carefully stored away from light and moisture.

 

Differential Scanning Technology (DSC)

The thermal behaviour of the cocrystal was determined using the Perkin Elmer Model STA-8000 with DSC. Before measurement, the instrument was calibrated for temperature and heat flow using standard indium. A weighted sample (5 mg) was placed in a sealed non-hermetic aluminium pan, and a hold time of 1 minute at 45°C was maintained. The measurement was then conducted with an increasing step size of 10°C/min under a dry nitrogen atmosphere, running the sample from 45°C to 235°C. Subsequently, the peaks were estimated, and the resulting data were analyzed using the simultaneous thermal analyzer DSC from PerkinElmer.

 

Powder X-ray diffraction (PXRD)

The distinct peak of each compound was characterized using PXRD. Subsequently, various brands of marketed products in India were assessed against Azmarda tablets to investigate the presence of the innovative cocrystal in the formulation. All samples, within an uncertainty range of (5 mg - 20g), were weighed using an analytical balance (Mettler Toledo). The product underwent powder X-ray diffraction (PXRD) analysis, with samples exposed to Cu Kα radiation (0.15405 nm) at a tube voltage of 40 kV and a current of 30 mA. Data were collected within the 2θ range of 2° to 49.721°, employing a step size of 0.031 under atmospheric pressure. For sample preparation, the required quantity was taken into a mortar, and a fine powder was gently obtained using a pestle. The powdered sample was then placed on the sample holder, packed, and the surface was smoothed with a microscopic slide.

 

Sodium content determination

Sodium content was determined using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES; Agilent 5110 Instrument) for the sacubitril/valsartan sodium complex, Azmarda, and sacubitril/valsartan tablets. Sodium content of different marketed products of sacubitril/valsartan tablets was measured with parameters including radio frequency (RF) power ranging from 750W to 950W, atomizer airshed set at 1.00 to 1.25 L/min, assisted gas flow between 0.5 to 1.00 L/min, and a vertical observation height of 15 to 18 mm.

For sample preparation, 1.0 g of the sample was transferred into a 100.0 mL Teflon/PTFE vessel, followed by the addition of 1.0 mL of hydrogen peroxide and 10.0 mL of concentrated nitric acid. The Teflon/polytetrafluoroethylene (PTFE) vessel was then placed in a microwave digestion apparatus. After cooling the mixture to room temperature, the plasma was ignited and allowed to stabilize for approximately 15 minutes. The blank solution was aspirated, and the signal was zeroed. In triplicate cycles, the diluent, standard, and sample solutions were aspirated into the plasma, and the ionization intensity of different elements was measured.

 

Dissolution studies

The dissolution studies were conducted in 900 mL of 0.1N HCl and pH 6.8 phosphate buffers using a USP Type II dissolution apparatus (Lab India DS 14000 SMART) with a paddle speed set at 75 rpm. Various marketed products of sacubitril/valsartan tablets were subjected to dissolution studies. The temperature of the dissolution medium was maintained at 37°C ± 0.5°C throughout the specified time limit. Tablet samples of marketed products were subjected to the dissolution study. The 10 mL sample aliquots were collected at 15, 30, 45 min time points from the dissolution vessel and same were replaced with an equal volume of fresh medium. The sample aliquot solution was then filtered through a 0.45 μ polyvinylidene difluoride (PVDF) filter (Make: Millipore) for analysis at 242 nm using the HPLC.

RESULTS

A total of 16 brands of marketed product of sacubitril/valsartan tablets, including Azmarda were studied in the present analysis.

The DSC thermograms of marketed products was determined for 11 brands including Azmarda indicating exothermic peaks for sacubitril/valsartan between 131°C and 165°C and 72°C and 114°C, respectively (Table 1, Figure 1). A distinct melting pattern was observed in the reference product, with exothermic peaks of sacubitril/valsartan detected at 140°C and 102°C, respectively.

The PXRD analysis revealed that none of the products exhibited the same crystal lattice as Azmarda tablets. The prominent peaks of Azmarda were observed at position of 2θ, specifically at 4.125, 5.267, 12.482, and 22.496 (Figure 2 and 3). Among other comparators, brand-9 showed three peaks around 2θ value of 4.082, 5.047 and 12.420. Brand 5, 8, 11, 13 and 14 showed two peaks around 2θ value 4 and 5; brand 12 showed two peaks around 2θ value of 4.391 and 5.917; brand 2, 4, 7 and 10 showed two peaks around 2θ value of 4 and 22; however, brand 3, 15 and 16 showed only peak around 2θ value of 4. The prominent peaks of Azmarda in PXRD pattern confirmed the crystalline nature of compound; as compared to all other brands.

Sodium content was determined for 11 brands including Azmarda. Analysis showed that Azmarda had a sodium level of 1.72%, which was comparable to the sodium levels in brand 2 (1.61%), brand 4 (1.73%), and brand 7 (1.58%) (Figure 4). Other marketed products had a higher sodium level ranging from 3.164 to 3.951.

The innovator product, Azmarda, based on cocrystal technology, demonstrated a 64% release of sacubitril and a 57% release of valsartan within 30 minutes in 0.1N HCl (Table 2, Figure 5 and 6). Marketed products such as brand 7, brand 12, and brand 13 showed 52%, 57%, and 52% release of sacubitril respectively, and 45%, 52%, and 48% release of valsartan,

respectively, in 30 minutes. Most of the marketed products exhibited very negligible drug release in 0.1N HCl. Similarly, within 45 minutes there was 68% release of sacubitril and 61% release of valsartan which was much higher than all other products. Sacubitril/valsartan are freely soluble in pH 6.8 phosphate buffer and complete drug release is observed in 30 minutes during dissolution study in pH 6.8 phosphate buffer (Table 3).

 

Table 1: Results of DSC data of sacubitril/valsartan tablets of marketed products

Brand name

Melting point

of sacubitril 133°C-136°C exotherm observed on temperature (°C)

Melting point

of valsartan 80°C-95°C exotherm observed on temperature (°C)

Brand 1 (Azmarda)

140

102

Brand 2

130

85

Brand 3

134-163

72-113

Brand 4

138

75

Brand 5

137

101

Brand 6

137

101

Brand 7

131

90

Brand 8

140

103

Brand 9

140

110

Brand 10

134-165

75-114

Brand 11

134-165

81-102

 

 

 

 

Table 2: Dissolution data of marketed products in 0.1N HCl

Sacubitril/valsartan tablets 50 mg dissolution with 0.1N HCl

Brand name

% Release

15 min

30 min

45 min

Sacubitril

Valsartan

Sacubitril

Valsartan

Sacubitril

Valsartan

Brand 1 (Azmarda)

52

46

64

57

68

61

Brand 2

15

15

31

29

39

37

Brand 3

6

6

8

7

9

8

Brand 4

3

3

7

6

9

8

Brand 5

1

1

1

1

1

1

Brand 6

1

1

2

2

3

4

Brand 7

39

33

52

45

64

55

Brand 8

5

5

7

6

15

13

Brand 9

7

8

9

9

10

11

Brand 10

2

1

16

6

5

4

Brand 11

1

1

2

2

3

3

Brand 12

53

49

57

52

61

57

Brand 13

42

39

52

48

59

54

Brand 14

1

1

2

2

3

3

Brand 15

8

8

12

13

15

16

Brand 16

2

2

3

2

3

3

 

Table 3: Dissolution data of marketed products in pH 6.8 phosphate Buffer

Sacubitril/valsartan tablets 50 mg dissolution results with pH 6.8 phosphate buffer

Brand name

% Release

5 min

10 min

15 min

30 min

45 min

Sacubitril

Valsartan

Sacubitril

Valsartan

Sacubitril

Valsartan

Sacubitril

Valsartan

Sacubitril

Valsartan

Brand 1 (Azmarda)

50

50

88

88

102

101

100

99

98

97

Brand 2

30

35

62

70

84

93

95

105

93

103

Brand 3

59

61

95

98

102

102

99

101

99

101

Brand 4

10

10

53

54

98

100

101

103

99

100

Brand 5

35

35

76

75

99

98

100

100

98

97

Brand 6

52

52

88

87

103

103

95

94

96

95

Brand 7

45

48

85

88

100

99

98

99

97

100

Brand 8

39

39

90

88

103

101

102

100

100

98

Brand 9

60

61

97

98

103

103

102

102

103

103

Brand 10

44

44

80

80

97

95

98

98

100

98

Brand 11

58

59

96

97

102

104

99

100

100

100

Brand 12

78

81

98

103

101

102

97

101

99

103

Brand 13

50

51

91

91

102

102

100

99

100

100

Brand 14

54

53

93

92

102

102

98

97

99

97

Brand 15

58

60

92

94

100

102

96

98

95

97

Brand 16

67

68

100

101

102

103

100

101

101

102

 

Figure 2. Powder X-ray diffraction profile of sacubitril/valsartan

 

Figure 3.  The characteristics powder diffraction peaks are described in terms of 2θ values for different marketed samples