Liquid loadable tablets of neusilin® us2 - a new approach to tabletting lipid formulations, the case of cyclosporine a

Liquid loadable tablets of Neusilin® US2 - A new
approach to tabletting lipid formulations, the case of
Cyclosporine A
"The liquid loadable tablets of Neusilin® US2 was able to absorb up to 2.2
ml/g of Cyclosporine A in lipid formulation according to a new study by
Camilla Sander and Per Holm (2009). Furthermore, bioavailability of
Cyclosporine A from liquid loadable tablets of Neusilin® US2 was almost
equal with soft gelatin and hard gelatin capsule formulations."

Are you facing the chal enges of converting SMEDDS/SEDDS formulations into oral solid dosageforms? A simple way to achieve could be through liquid loadable tablets of Neusilin® US2.
Introduction
The transformation of self-micro emulsifying drug delivery systems (SMEDDS) or lipid formulations
into a solid dosage form can be carried out by capsule fil ing, spray drying, adsorption on to solid
carriers, and melt granulation as wel as other techniques. Among these techniques, capsule fil ing
and absorption on to solid carrier techniques are more popular. However, the capsule fil ing
techniques are usual y associated with some problems such as leaking, leaching of liquid through the
capsule shel , and incompatibilities with capsule materials. On the other hand, adsorption onto solid
carrier techniques also has some concerns such as large amount of carrier required or large dosage
volume, sticking, liquid exudation, and low tablet hardness. In a new study by Camil a Sander and Per
Holm (2009), Cyclosporine A (CyA) SMEDDS with Neusilin® was used as a drug model for liquid
loadable tablets (LLT). Placebo tablets of Neusilin® US2 (Magnesium Aluminometasilicate or MAMS)
prepared by direct compression was loaded with CyA-SMEDDS to prepare liquid loadable tablets.
This is a novel approach to transform liquid lipid formulations into solid dosage forms [1].
Fig.1 Preparation of liquid loadable tablets Cyclosporin A is an immunosuppressant drug widely used in post-al ogeneic organ transplant to reducethe activity of the patient's immune system. Cyclosporine A exhibits very poor solubility in water, and,as a consequence, suspension and emulsion forms of the drug have been developed for oraladministration and for injection.
Experimental methods
The test formulations are showed in Table 1. The LLTs of approximately 250 mg were made by direct
compression of Neusilin® US2 with and without crospovidone, assigned as LLT-2 and LLT-1,
respectively (Fig.1). The composition of LLT-1 (F2) was MAMS/Magnesium stearate (99:1w/w%),
whereas the composition of LLT-2 (F6) was MAMS/Crospovidone/Magnesium stearate
(89:10:1w/w%). The placebo tablets with hardness above 50 N and porosity of approximately 80%
were achieved at compression forces around 15-22 MPa with conventional tabletting equipments. The
LLTs were placed in excess of CyA-SMEDDS and allowed to absorb until constant tablet weight was
reached. Excess liquid on the surface was removed by tissue paper. The tablets were dried by
storage for few hours. No leaking was observed. Bioavailability tests were carried out using beagle
dogs.
Table1. Test formulations

CyA-SMEDDS and filled hard gelatincapsule Results
The volume-based loading capacity of the LLTs was found to be comparable to soft gelatin capsule
and hard gelatin capsules, 458.3 mg and 250.5 mg of CyA-SMEDDS for LLT-1 and LLT-2,
respectively. Addition of 10% disintegrant into LLT-2 improved the dissolution rate markedly to
approximately 50% in comparison with dissolution rate of LLT-1. The LLTs of Neusilin® US2 were able
to absorb up to 2.2 ml/g of CyA-SMEDDS. Bioavailability of CyA from LLT-2 (F6) was almost equal
with soft gelatin capsule (F3, Neoral® from Novartis Healthcare A/S) and hard gelatin capsule (F5,
Capsugel, Pfizer Inc.). Notably, formulation F5 using Neusilin® US2 as adsorption carrier of
CyA-SMEDDS had the same bioavailability to that of soft gelatin capsule (F3) (Table 2).
Neusilin® US2 with large specific surface area (≈300 m2/g) and high adsorption capacity (≈3 ml/g) hasproved to be an excel ent excipient for manufacturing LLTs of SMEDDS formulations. In addition,Neusilin® US2 could also be used as an adsorbent carrier to prepare hard gelatin capsules toovercome the problems such as leaking, leaching of liquid through the capsule shell, or incompatibilitieswith capsule materials.
Table2. Mean pharmacokinetic parameters after single-dose administration of CyA in dog
*: Relative bioavailability is compared with Neoral® F3
Conclusions
The study showed successful approach using Neusilin® US2 as a suitable adsorption carrier for liquid
loadable tablets to transform SMEDDS into solid dosage forms, as wel as for hard gelatin capsules.
In the case of CyA, the LLTs of Neusilin® US2 demonstrated some advantages:
Consistent content of CyA, high tablet hardness, and high loading capacity were achieved.
Bioavailability of CyA from the LLTs was comparable to bioavailability from capsules.
The LLTs were easily prepared by direct compression with conventional tabletting equipments.
No leaking of the liquid content on the surface of the LLTs.
The manufacturing process can easily be scaled up.
In conclusion, the LLT technology can be a promising approach to achieve oral solid dosage formsfrom liquid lipid formulations.
Reference
1. Sander C, Holm P. Porous magnesium aluminometasilicate tablets as carrier of a cyclosporine self-emulsifying
formulation. AAPS PharmSciTech. 2009. 10:1388-95
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