In vivo release of cisplatin from a needle-type copolymer formulation implanted in rat kidney

Changes in cisplatin delivery due to surface-coated poly (lactic acid)-poly(epsilon-caprolactone) microspheres

Smooth muscle cell proliferation plays a major role in the genesis of restenosis after angioplasty or vascular injury. Local delivery of agents capable of modulating vascular responses, have the potential to prevent restenosis. However, the development of injectable microspheres for sustained drug delivery to the arterial wall is a major challenge. We demonstrated the possibility of entrapping an antiproliferative agent, cisplatin, in a series of surface coated biodegradable microspheres composed of poly(lactic acid)poly(caprolactone) blends, with a mean diameter of 2-10 pm. The microspheres were surface coated with poly ethylene glycol (PEG), chitosan (Chit), or alginate (Alg). A solution of cisplatin and a 50:50 blend of polylactic acid (PLA)-polycaprolactone (PCL) dissolved in acetone-dichloromethane mixture was poured into an aqueous solution of PEG (or polyvinyl alcohol or Chit or Alg) with stirring using a high speed homogenizer, for the formation of microspheres. Cisplatin recovery in microspheres ranged from 25-45% depending on the emulsification system used for the preparations. Scanning electron microscopy revealed that the PLA-PCL microspheres were spherical in shape and had a smooth surface texture. The amount of drug release was much higher initially (20-30%), this was followed by a constant slow-release profile for a 30-day period of study. It has been found that drug release depends on the amount of entrapped drug, on the presence of extra cisplatin in the dispensing phase, and on the polymer coatings. This PEG or Alg-coated PLA/PCL microsphere formulation may have potential for the targeted delivery of antiproliferative agents to treat restenosis.

Effects of cis-diamminedichloroplatinum II released from D,L-polylactic acid implanted adjacent to cortical allografts in dogs

This study was performed to determine the pharmacokinetics and local and systemic effects of cis-diamminedichloroplatinum II (cisplatin) released from an open-cell polylactic acid polymer when the drug delivery device was placed adjacent to a cortical allograft. Bilateral intercalary femoral allografts were implanted in six normal beagles. The polymer containing cisplatin was implanted adjacent to the allograft in one femur, and the polymer without cisplatin was implanted adjacent to the allograft in the contralateral femur. Systemic toxicity was evaluated clinically by hematologic and serum biochemistry tests and urinalysis. Healing of the allograft was monitored radiographically. The femora were evaluated biomechanically, histologically, and histomorphometrically 7.5 months after surgery. Total serum platinum levels were measured by atomic absorption spectrophotometry, and pharmacokinetic parameters were calculated. Healing was impaired slightly by the presence of the polymer with cisplatin, and systemic and local toxicity was mild and transient. After implantation of the polymer with cisplatin, the mean peak total serum platinum concentration was low (1.71 +/- 0.19 micrograms/ml). However, the area under the curve for total serum platinum concentration versus time for the first 21 days was large (27,050 +/- 3,201 micrograms.min/ml). When cisplatin was given as an intravenous bolus at a dose of 70 mg/m2 to six other beagles, the mean peak total platinum concentration was 8.80 +/- 2.1 micrograms/ml and the area under the curve was 940.3 +/- 256.7 micrograms.min/ml. These results indicate that a sustained release of cisplatin can be delivered safely from an open-cell polylactic acid polymer. This device may be useful in the treatment of solid tumors.

Treatment of malignant pleural effusions with doxorubicin hydrochloride-containing poly(L-lactic acid) microspheres

For the treatment of malignant pleural effusions, we prepared doxorubicin hydrochloride (Adriamycin)-containing poly(L-lactic acid) microspheres (ADR-MS). In vitro, 50 percent and 100 percent release times of ADR from ADR-MS were 6.3 and 20 days, respectively. After intrapleural administration of ADR-MS for seven patients at an ADR dose of 40 mg, ADR was detected in the effusions for more than two weeks; however, ADR concentrations in serum were very small, consistent with minimal transpleural absorption of ADR. These results indicated the slow release of ADR into the pleural cavity. Furthermore, the amount of drained ADR was less than a few percent of the administered dose. In some cases, malignant cells in the effusion disappeared after the treatment. No complications related to the procedure occurred, and the patients developed no systemic symptoms. One patient died after four months, and the other six patients are alive after 21 to 31 months without reaccumulation of the effusion. The local administration of ADR-MS produces a localized high and systemic low concentration of ADR, which could potentially improve the patient's quality of life.