Pharmaceutical Research

, Volume 25, Issue 3, pp 586–597 | Cite as

Formulation and Characterization of Injectable Poly(dl-lactide-co-glycolide) Implants Loaded with N-Acetylcysteine, a MMP Inhibitor

  • Kashappa Goud H. Desai
  • Susan R. Mallery
  • Steven P. Schwendeman
Research Paper

Abstract

Purpose

The objective of this study was to develop poly(lactic-co-glycolic acid) (PLGA) injectable implants (i.e., millicylinders) with microencapsulated N-acetylcysteine (NAC) for site-specific controlled NAC release, for potential chemopreventive applications in persons with previously excised head and neck cancers.

Methods

PLGA 50:50 (i.v. = 0.57 dl/g) implants with 1–10 wt% NAC free acid or 10 wt% NAC salts (NAC–Na+, NAC–Mg2+ and NAC–Ca2+) were prepared by solvent extrusion and/or fluid energy micronization (FEM) methods. X-ray diffraction (XRD), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC) studies were performed to evaluate the physical mixing of NAC with PLGA. PLGA implant degradation was studied by kinetics of polymer molecular weight decline (gel permeation chromatography) and mass loss. Release studies were conducted in N2 purged PBS (pH 7.4) at 37°C in evacuated and sealed ampoules. NAC was quantified by HPLC at 210 nm.

Results

XRD, SEM and DSC studies indicated that NAC had dissolved in the polymer phase at 1–3.5% w/w loading, but became discretely suspended in the polymer at 6–10% w/w. Initial burst and long-term release rate increased with increased drug loading, and release was uncharacteristically rapid at higher loading (6–10% w/w). The cause of the rapid release was linked to extensive plasticization, matrix porosity and general acid catalysis of PLGA degradation caused by the NAC free acid. PLGA millicylinders loaded with 10% w/w NAC–Ca2+ and NAC–Mg2+salts exhibited reduced burst (34 vs 13–22% release within a day of incubation for NAC free acid vs NAC–Ca2+ and NAC–Mg2+salts, respectively) and slow and continuous complete release over 4 weeks without significant NAC-catalyzed degradation of PLGA. Release of NAC from NAC–Ca2+/PLGA implant was slower than that of NAC–Mg2+/PLGA consistent with the lower solubility of the former salt. NAC with its free thiol was rapidly converted to its cystine dimer in the presence of molecular oxygen. PLGA released samples in sealed and evacuated ampoules indicated >80% parent NAC remaining after the 1 month release analysis irrespective of initial NAC free acid and salt forms.

Conclusion

By encapsulating the NAC–Mg2+ and NAC–Ca2+ salts in PLGA implants, the high initial burst, short release duration, and the general acid catalysis caused by the NAC free acid were each prevented and 1-month slow and continuous release was attained with minimal instability of the free thiol group.

Key words

burst effect controlled release drug induced plasticization drug induced PLGA degradation head and neck cancer N Acetylcysteine NAC salts PLGA degradation PLGA implants 

References

  1. 1.
    A. Jemal, R. Siegel, E. Ward, T. Murray, J. Q. Xu, and M. J. Thun. Cancer statistics. CA-Cancer. J. Clin. 57:43–66 (2007).PubMedCrossRefGoogle Scholar
  2. 2.
    A. A. Forastiere. Head and neck cancer: Overview of recent developments and future directions. Semin. Oncol. 27:1–4 (2000).PubMedGoogle Scholar
  3. 3.
    I. Ganly and S. B. Kaye. Recurrent squamous-cell carcinoma of the head and neck: Overview of current therapy and future prospects. Ann. Oncol. 11:11–16 (2000).PubMedCrossRefGoogle Scholar
  4. 4.
    N. H. Shah, A. S. Railkar, F. C. Chen, R. Tarantino, S. Kumar, M. Murjani, D. Palmer, M. H. Infeld, and A. W. Malick. A biodegradable injectable implant for delivering micromolecules and macromolecules using poly(lactic-co-glycolic) acid (PLGA) copolymers. J. Controlled Release. 27:139–147 (1993).CrossRefGoogle Scholar
  5. 5.
    O. Sartor, M. K. Dineen, R. Perez-Marreno, F. M. Chu, G. J. Carron, and R. C. Tyler. An eight-month clinical study of LA-2575 30.0 mg: A new 4-month, subcutaneous delivery system for leuprolide acetate in the treatment of prostate cancer. Urology. 62:319–323 (2003).PubMedCrossRefGoogle Scholar
  6. 6.
    P. Sampath and H. Brem. Implantable slow-release chemotherapeutic polymers for the treatment of malignant brain tumors. Cancer Contl. 5:130–137 (1997).Google Scholar
  7. 7.
    S. R. Mallery, P. Pei, J. C. Kang, G. M. Ness, R. Ortiz, J. E. Touhalisky, and S. P. Schwendeman. Controlled-release of doxorubicin from poly(lactide-co-glycolide) microspheres significantly enhances cytotoxicity against cultured AIDS-related kaposi’s sarcoma cells. Anticancer. Res. 20:2817–2825 (2000).PubMedGoogle Scholar
  8. 8.
    E. D. Crawford, O. Sartor, F. Chu, R. Perez, G. Karlin, and J. S. Garrett. A 12-month clinical study of LA-2585 (45.0 MG): A new 6-month subcutaneous delivery system for Leuprolide acetate for the treatment of prostate cancer. J. Urology. 175:533–536 (2006).CrossRefGoogle Scholar
  9. 9.
    J. Westermarck and V. M. Kahari. Regulation of matrix metalloproteinase expression in turner invasion. FASEB J. 13:781–792 (1999).PubMedGoogle Scholar
  10. 10.
    S. Curran and G. I. Murray. Matrix metalloproteinases in tumour invasion and metastasis. J. Pathol. 189:300–308 (1999).PubMedCrossRefGoogle Scholar
  11. 11.
    S. Kurahara, M. Shinohara, T. Ikebe, S. Nakamura, M. Beppu, A. Hiraki, H. Takeuchi, and K. Shirasuna. Expression of MMPs, MT–MMP, and TIMPs in squamous cell carcinoma of the oral cavity: Correlations with tumor invasion and metastasis. Head. Neck—J. Sci. Spec. 21:627–638 (1999).CrossRefGoogle Scholar
  12. 12.
    E. A. Garbett, M. W. R. Reed, and N. J. Brown. Proteolysis in human breast and colorectal cancer. Brit. J. Cancer. 81:287–293 (1999).PubMedCrossRefGoogle Scholar
  13. 13.
    A. Franchi, M. Santucci, E. Masini, I. Sardi, M. Paglierani, and O. Gallo. Expression of matrix metalloproteinase 1, matrix metalloproteinase 2, and matrix metalloproteinase 9 in carcinoma of the head and neck—Correlation with p53 status, inducible nitric oxide synthase activity, and anigogenesis. Cancer Res. 95:1902–1910 (2002).Google Scholar
  14. 14.
    P. Pei, M. P. Horan, R. Hille, C. F. Hemann, S. P. Schwendeman, and S. R. Mallery. Reduced nonprotein thiols inhibit activation and function of MMP-9: Implications for chemoprevention. Free Radical. Bio. Med. 41:1315–1324 (2006).CrossRefGoogle Scholar
  15. 15.
    A. Rieutord, P. Arnaud, J. F. Dauphin, and F. Brion. Stability and compatibility of an aerosol mixture including N-acetylcysteine, netilmicin and betamethasone. Int. J. Pharm. 190:103–107 (1999).PubMedCrossRefGoogle Scholar
  16. 16.
    M. Zafarullah, W. Q. Li, J. Sylvester, and M. Ahmad. Molecular mechanisms of N-acetylcysteine actions. Cell. Mol. Life. Sci. 60:6–20 (2003).PubMedCrossRefGoogle Scholar
  17. 17.
    T. H. Zhou, H. Lewis, R. E. Foster, and S. P. Schwendeman. Development of a multiple-drug delivery implant for intraocular management of proliferative vitreoretinopathy. J. Controlled Release. 55:281–295 (1998).CrossRefGoogle Scholar
  18. 18.
    G. Bleau, C. Giasson, and I. Brunette. Measurement of hydrogen peroxide in biological samples containing high levels of ascorbic acid. Anal. Biochem. 263:13–17 (1998).PubMedCrossRefGoogle Scholar
  19. 19.
  20. 20.
    S. A. Seo, H. S. Choi, G. Khang, J. M. Rhee, and H. B. Lee. A local delivery system for fentanyl based on biodegradable poly(l-lactide-co-glycolide) oligomer. Int. J. Pharm. 239:93–101 (2002).PubMedCrossRefGoogle Scholar
  21. 21.
    S. Li, M. Vert. Crystalline oligomeric stereocomplex as an intermediate compound in racemic poly(dl-lactic acid) degradation. Polym. Int. 33:37–41 (1994).Google Scholar
  22. 22.
    F. Alexis. Factors affecting the degradation and drug-release mechanism of poly(lactic acid) and poly[(lactic acid)-co-(glycolic acid)]. Polym. Int. 54:36–46 (2005).CrossRefGoogle Scholar
  23. 23.
    J. C. Kang and S. P. Schwendeman. Determination of diffusion coefficient of a small hydrophobic probe in poly(lactide-co-glycolide) microparticles by laser scanning confocal microscopy. Macromolecules. 36:1324–1330 (2003).CrossRefGoogle Scholar
  24. 24.
    M. Benrahmoune, M. Ghassah, and Z. Abedinzadeh. Superoxide radicals action on N-acetylcysteine. J. Chim. Phys. PCB. 94:257–261 (1997).Google Scholar
  25. 25.
    G. A. Bagiyan, I. K. Koroleva, N. V. Soroka, and A. V. Ufimtsev. Oxidation of thiol compounds by molecular oxygen in aqueous solutions. Russ. Chem. B+. 52:1135–1141 (2003).CrossRefGoogle Scholar
  26. 26.
    M. Benrahmoune, P. Therond, and Z. Abedinzadeh. The reaction of superoxide radical with N-acetylcysteine. Free Radical. Bio. Med. 29:775–782 (2000).CrossRefGoogle Scholar
  27. 27.
    H. O. M. Yamamoto, Y. Ogawa, T. Miyagawa. US Patent 4,728,721 (1988).Google Scholar
  28. 28.
    J. Inczedy and J. Marothy. Metal-Complexes of N–Acetyl–Cysteine. Acta. Chim. Hung. 86:1–2 (1975).Google Scholar
  29. 29.
    V. Smuleac, D. A. Butterfield, S. K. Sikdar, R. S. Varma, and D. Bhattacharyya. Polythiol-functionalized alumina membranes for mercury capture. J. Membrane Sci. 251:169–178 (2005).CrossRefGoogle Scholar
  30. 30.
    M. Ara, M. Watanabe, and Y. Imai. Effect of blending calcium compounds on hydrolytic degradation of poly(dl-lactic acid-co-glycolic acid). Biomaterials. 23:2479–2483 (2002).PubMedCrossRefGoogle Scholar
  31. 31.
    Y. Zhang, S. Zale, L. Sawyer, and H. Bernstein. Effects of metal salts on poly(dl-lactide-co-glycolide) polymer hydrolysis. J. Biomed. Mater. Res. 34:531–538 (1997).PubMedCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2007

Authors and Affiliations

  • Kashappa Goud H. Desai
    • 1
  • Susan R. Mallery
    • 2
  • Steven P. Schwendeman
    • 1
  1. 1.Department of Pharmaceutical SciencesUniversity of MichiganAnn ArborUSA
  2. 2.Department of Oral Maxillofacial Surgery and Pathology, College of Dentistry and the Comprehensive Cancer Center and Solove Research InstituteThe Ohio State UniversityColumbusUSA

Personalised recommendations