Desensitization to Asparaginase

 

Protocol:

(1) Administer a test dose (intradermal injection of 2 IU) to determine if desensitization is required. The presence of erythema or a wheal indicates a positive reaction, and the desensitization protocol should be followed. The occurrence of a serious allergic reaction to the test dose is a contraindication to further administration, and an alternative therapeutic regimen should be considered.

 

(2) Determine the total dose to administer based on body weight in kilograms (probably ideal body weight) and dose per kilogram:

 

total dose to administer in IU =

= (dose in IU per kg) * (body weight in kilograms)

 

(3) Look up closest cumulative dose in the table below and determine the number of injections required to achieve this dose.

 

(4) Doses are administered every 10 minutes IV until the cumulative dose has been delivered OR a hypersensitivity reaction develops, at which time the protocol is discontinued and the reaction treated.

 

(5) If all of the doses are administered, the total administration time will be (with the first injection as t = 0):

 

total administration time in minutes =

= ((number of injections required) – 1) * 10

 

(6) If the target dose is between intervals in the table, there are 2 options:

(a) Stop at the lower level.

(b) Administer a final injection to achieve the final dose.

 

Number of Injections	Injection Dose in IU	Cumulative Dose Administered in IU
1	1	1
2	2	3
3	4	7
4	8	15
5	16	31
6	32	63
7	64	127
8	128	255
9	256	511
10	512	1023
11	1024	2047
12	2048	4095
13	4096	8191
14	8192	16383
15	16384	32767
16	32768	65535
17	65536	131071
18	131072	262143

 

where:

• The injection dose is a power of 2, starting with 2^0.

• The cumulative dose = 2^0 + 2^1 + …. + 2^((injections) – 1)