Enhanced oral bioavailability of calcium using bovine serum albumin microspheres

Figures & data

Table 1.  Composition of calcium loaded BSA microspheres.

Formulation	Drug:polymer ratio (% w/w)	Glutaraldehyde amount (mL)	Cross linking time (h)
F1	1:0.5	0.5	12
F2	1:0.5	1	12
F3	1:1	0.5	12
F4	1:1	1	12

Table 2.  Physicochemical characteristics of calcium loaded BSA microspheres.*

Formulations	Drug:polymer ratio	%EE	% yield	Particle size (µm)	Zeta potential (mV)	Polydispersity
F1	1:0.5	50.21 ± 3.14	72.82 ± 4.44	7.77 ± 0.52	−33.91 ± 2.22	0.80 ± 0.06
F2	1:0.5	54.72 ± 2.01	73.11 ± 3.97	8.34 ± 0.32	−34.65 ± 1.01	0.88 ± 0.05
F3	1:1	60.43 ± 2.47	82.75 ± 4.17	1.85 ± 0.25	−32.96 ± 1.42	0.70 ± 0.07
F4	1:1	72.11 ± 2.57	80.93 ± 5.49	2.29 ± 0.45	−30.91 ± 3.06	0.61 ± 0.04

*Mean ± SD, n = 3, %EE: encapsulation efficiency, % yield: percentage yield.

Figure 1.  Scanning electron microscopy pictures of calcium loaded BSA microspheres (formulation F4) at magnification ×7000.

Figure 2.  In vitro release profiles of calcium loaded BSA microspheres in pH 1.2 for 2 h followed by pH 6.8 for 22 h. The data represents the mean ± SD of six determinations.

Figure 3.  Serum calcium profiles obtained after oral administration of calcium loaded BSA microspheres (F4) and control solution (~1 mL, dose of 30 mg/kg of calcium) in Sprague–Dawley rats. The data represent mean ± SD of six determinations.

Table 3.  Mean pharmacokinetic parameters of calcium in serum following oral administration of calcium loaded microspheres (F4) and control (~1 mL, dose of 30 mg/kg of calcium) for a period of 12 h in Sprague–Dawley rats (n = 6). Cmax indicates maximum concentration; Tmax, time of maximum concentration; Kel, elimination rate constant; AUC0–α, area under the serum concentration-time curve; T1/2, elimination half-life.

Parameter	Calcium loaded microspheres	Control
Tmax (h)	2.0	5.0
Cmax (mg/dL)	0.20 ± 0.04	0.11 ± 0.02
AUC0–α (mg.h/dL)	1.56 ± 0.29	0.68 ± 0.07
T1/2 (h)	4.65 ± 0.53	5.11 ± 0.87
Kel	0.15 ± 0.04	0.14 ± 0.05