Gentamicin release from modified acrylic bone cements with lactose and hydroxypropylmethylcellulose

Area of Science:

• Biomaterials Science
• Drug Delivery Systems
• Orthopedic Surgery

Background:

• Polymethylmethacrylate (PMMA) bone cements are widely used in orthopedic surgery.
• Gentamicin is frequently incorporated into bone cements to prevent infection.
• Controlling gentamicin release from PMMA bone cements is crucial for efficacy and minimizing resistance.

Purpose of the Study:

• To investigate the effect of incorporating lactose or hydroxypropylmethylcellulose (HPMC) as release modulators on gentamicin release from PMMA bone cements.
• To characterize the surface morphology and porosity of these modified bone cement formulations.
• To compare the gentamicin release profiles with a commercial gentamicin-loaded bone cement.

Main Methods:

• Modified PMMA bone cement formulations were prepared with varying proportions of gentamicin and release modulators (lactose or HPMC).
• Surface morphology was analyzed using scanning electron microscopy (SEM).
• Gentamicin release was quantified using a specialized dissolution system, and porosity was measured by mercury intrusion porosimetry.

Main Results:

• Lactose-modified cements exhibited irregular surfaces with voids and significantly higher gentamicin release (up to 13%) compared to commercial cement (3%).
• Gentamicin release from lactose formulations correlated positively with increased lactose concentration and porosity.
• HPMC incorporation increased cement porosity but did not enhance gentamicin release, likely due to the formation of a viscous gel hindering elution.

Conclusions:

• Lactose is an effective release modulator for increasing gentamicin elution from PMMA bone cements, with release proportional to concentration.
• HPMC, while increasing porosity, does not enhance gentamicin release and may impede it.
• These findings offer insights for designing PMMA bone cements with tailored antibiotic release profiles for infection prophylaxis.