title: Microparticulate drug delivery system containing tramadol hydrochloride for pain treatment.
abstract: The current trend of replacing conventional pharmaceutical forms is justified because most substances administered in this form give fluctuations of therapeutic concentrations and often outside the therapeutic range. In addition, these formulations offer a reduction in the dose or the number of administrations, thus increasing patient compliance.
  
  
  OBJECTIVE
  In the experiment, we developed an appropriate technology for the preparation of gelatin microspheres containing tramadol hydrochloride by emulsification/cross-linking method.
  
  
  METHODS
  The formulated microspheres were characterized by product yield, size distribution, encapsulation efficiency and in vitro release of tramadol hydrochloride. Data obtained from in vitro release studies were fitted to various mathematical models to elucidate the transport mechanisms. The kinetic models used were zero-order, first-order, Higuchi Korsmeyer-Peppas and Hopfenberg.
  
  
  RESULTS
  Spherical microspheres were obtained, with free-flowing properties. The entrapment efficiency of tramadol hydrochloride in microparticles was 79.91% and product yield -94.92%. As the microsphere size was increased, the entrapment efficiency increased. This was 67.56, 70.03, 79.91% for formulations MT80-250, MT8-500 and, MT250-500. High entrapment efficiency was observed for MT250-500 formulation. The gelatin microspheres had particle sizes ranging from 80 to 500 microm. The drug was released for a period of 12 hours with a maximum release of 96.02%. Of the three proposed formulations, MT250-500 presented desirable properties and optimal characteristics for the therapy of pain. Release of tramadol hydrochloridi was best fitted to Korsmeyer-Peppas equation because the Akaike Information Criterion had the lowest values for this kinetic model.
  
  
  CONCLUSIONS
  These results suggest the opportunity to influence the therapeutic characteristics of gelatin microspheres to obtain a suitable drug delivery system for the oral administration of tramadol hydrochloride.
authors.affiliation: University of Medicine and Pharmacy from Târgu Mureş, Romania, Department of Pharmaceutical Technology.
authors.forename: Adriana
authors.initials: A
authors.lastname: Ciurba
authors.forename: Nicoleta
authors.initials: N
authors.lastname: Todoran
authors.forename: C E
authors.initials: CE
authors.lastname: Vari
authors.forename: Luminita
authors.initials: L
authors.lastname: Lazăr
authors.forename: Stela
authors.initials: S
authors.lastname: Al Hussein
authors.forename: G
authors.initials: G
authors.lastname: Hancu
mesh_terms: D000284:Administration, Oral; D000701:Analgesics, Opioid / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D016503:Drug Delivery Systems / Q000379:methods; D006801:Humans; D008863:Microspheres; D010146:Pain / Q000188:drug therapy; D059408:Pain Management / Q000379:methods; D014147:Tramadol / Q000008:administration & dosage* / Q000493:pharmacokinetics*
chemical_list: D000701:Analgesics, Opioid; D014147:Tramadol