The ALZAID Chemical Compatibility Test Kit allows researchers to determine the compatibility of solvents and agents with ALZET Osmotic Pumps.

The Test Kit contains polymer spheres that are chemically identical to the polymer used in the reservoir of ALZET pumps. The polymer spheres have been processed in the same manner as the drug reservoir, and have been sterilized with gamma irradiation. The kit contains materials for evaluating four solutions.

Use of the ALZAID kit is strongly recommended under the following circumstances:

  • The desired solvent is not known to be compatible with the pump reservoir (refer to list of compatible solvents)
  • The agent is in its free base form
  • The agent is known to bind tenaciously to polymeric materials

The ALZAID test kit can be used to determine the compatibility of the solvent alone or agent-solvent combinations by following the recommended procedures.

Procedure for Assessing Solvent Compatibility with ALZET pumps

  1. Count and weigh the contents of 1 bag of spheres for each test solution you wish to examine. Record the numbers of spheres and record their weight to the nearest 0.1 mg.
  2. Place the weighed group of spheres in a screw-cap test tube (approximately 10 ml in volume).
  3. Place 5 ml of the test solvent in the test tube and secure the cap.
  4. Incubate the spheres in the test solvent at 37 degree C for the desired duration of infusion. During the incubation period, the spheres may whiten (this color change is acceptable).
  5. Remove all of the polymer spheres from each test tube and blot dry with an absorbent tissue. Immediately count and weigh the group of spheres on an analytical balance to the nearest 0.1 mg. It is important to finish this step with the same number of spheres with which you began.
  6. For each test solvent, determine the quantity A using the following equation:
    1. [(Final Weight – Initial Weight) / Initial Weight] X 100 = A (%)
  7. If A is between 0-7%, the solvent is suitable for use with ALZET® Osmotic Pumps. If A is outside of this range (either negative or greater than 7%) or if the spheres deform in shape, the solution should NOT be used with ALZET® Osmotic Pumps.

Using an incompatible solvent?

An agent or solvent that is incompatible with the pump’s reservoir material may still be able to be delivered using an ALZET pump. This is done by attaching a catheter to the pump, and using it as an “external reservoir”. The contents of this external reservoir are displaced by the action of the pump. The external reservoir can be created easily, such as from coiled PE-60 catheter tubing, in a technique known as the Lynch coil. More about this simple technique

List of solvents known to be compatible with ALZET pumps

  • Acids, with pH greater than 1.8
  • Bases, with pH less than 14
  • Cremophor EL, up to 25% in water
  • Culture media (1% benzyl alcohol as bacteriostatic)
  • Cyclodextrins
  • Dextrose, up to 5%, in water or NaCl
  • N,N-Dimethyl formamide (DMF), up to 25% in water
  • DMSO, up to 50% in water or polyethylene glycol
  • DMSO, up to 50% in ethanol (< or = to 15%) and water
  • Ethanol, up to 15% in water
  • Glycerol
  • 1-Methyl-2-Pyrrolidone, up to 12.5% in water
  • Phosphate buffer
  • Polyethylene glycol 300 or 400, neat or in water
  • Propylene glycol, neat or in water
  • Ringer’s solution (with or without lactate)
  • Saline, 0.9% (or other aqueous salt solution)
  • Serum (rat, mouse, etc.)
  • Solutol, up to 30% in water
  • Triacetin, up to 5% in water
  • Tween 80, up to 2%
  • Water, distilled

Note: Ethanol is not compatible with the ALZET pump reservoir in concentrations exceeding 15%. This kit cannot be used to evaluate compatibility of solutions containing higher concentrations of ethanol since results will not be reliable.