Synthesis of an enzyme-dependent prodrug and evaluation of its potential for colon targeting

Table 1 Recovery of free dexamethasone from the rat blood and GI tract at various times after administration of DSD suspensions^a,b (equivalent to 15 mg of dexmethasone per kg body weight)

th	Tμg	Recovery of dexamethasone (%)
		B	S	PSI	DSI	Ce	Co
1	5.2	nd	74	26	nd	nd	nd
3	7.3	nd	54	nd	46	nd	nd
4	14	nd	8.8	6.6	10.2	54	20.5
5	27.6	nd	9.2	5.0	13.4	54.4	18.0
6	133	nd	4.0	0.27	2.2	83	10.2
7	128	nd	4.5	nd	0.557	80	15.2
9	105	nd	12.4	3.49	3.72	62	18.2

Table 2 Recovery of free dexamethasone from the rat blood and GI tract at various times after administration of dexamethasone suspensionsa, b (equivalent to 15 mg of dexmethasone per kg body weight)

th	Tμg	Recovery of dexamethasone (%)
		B	S	PSI	DSI	Ce	Co
1	1076	8.9	54	15.8	20.8	0.05	nd
3	857	4.58	94.6	0.05	1.08	nd	nd
4	390	26	58	10.2	5.0	0.40	nd
5	230	36	22	1.19	4.2	16	2.56
6	203	33	30	6.7	3.63	24.7	2.25
7	139	39	49	2.02	5.6	3.74	0.79
9	134	40	42	1.52	7.8	6.0	3.1

^aValues represent the average of three animals. ^bt, Time; T, Total recovery; B, Blood; S, Stomach; PSI, Proximal small intestine; DSI, Distal small intestine; Ce, Cecum; Co, Colon. nd: Not detected