Weijtens O, Feron E J, Schoemaker R C, Cohen A F, Lentjes E G, Romijn F P, van Meurs J C
Rotterdam Eye Hospital, The Netherlands.
Am J Ophthalmol. 1999 Aug;128(2):192-7. doi: 10.1016/s0002-9394(99)00129-4.
To determine the dexamethasone concentration in aqueous, vitreous, and serum of patients after a subconjunctival injection with dexamethasone disodium phosphate and to compare the effectiveness of a subconjunctival injection as a method of delivering dexamethasone into the vitreous with that of two previously tested routes: peribulbar injection and oral administration.
In a prospective study, 50 phakic patients who underwent a pars plana vitrectomy received a single subconjunctival injection with 2.5 mg of dexamethasone disodium phosphate, aqueous solution (after topical anesthesia and a subconjunctival injection with lidocaine) at varied intervals before surgery. An aqueous and a vitreous sample were taken from each patient, and serum samples were collected at multiple time points from nine of 50 patients. Dexamethasone concentrations were measured by radioimmunoassay.
The estimated maximum dexamethasone concentration in the aqueous was 858 ng per ml at 2.5 hours after injection, and in the vitreous, 72.5 ng per ml at 3 hours. In serum, a mean maximum concentration of 32.4 ng per ml was measured at approximately 30 minutes after injection.
Subconjunctival injection of 2.5 mg of dexamethasone disodium phosphate resulted in an estimated vitreous dexamethasone peak concentration three and 12 times higher, respectively, than after a peribulbar injection of 5 mg of dexamethasone disodium phosphate and an oral dose of 7.5 mg of dexamethasone. Thus, a subconjunctival injection is the most effective method of delivering dexamethasone into both the anterior and posterior segments of the eye. Systemic drug absorption is considerable and is of the same order of magnitude as after peribulbar injection.
测定磷酸地塞米松钠结膜下注射后患者房水、玻璃体和血清中的地塞米松浓度，并将结膜下注射作为向玻璃体输送地塞米松的一种方法与之前测试的两种途径（球周注射和口服给药）的有效性进行比较。
在一项前瞻性研究中，50例接受平坦部玻璃体切除术的有晶状体眼患者在手术前不同时间间隔接受单次结膜下注射2.5mg磷酸地塞米松钠水溶液（局部麻醉和利多卡因结膜下注射后）。从每位患者采集一份房水和一份玻璃体样本，并从50例患者中的9例在多个时间点采集血清样本。通过放射免疫测定法测量地塞米松浓度。
注射后2.5小时房水中地塞米松估计最大浓度为858ng/ml，玻璃体中3小时时为72.5ng/ml。血清中，注射后约30分钟测得平均最大浓度为32.4ng/ml。
结膜下注射2.5mg磷酸地塞米松钠导致玻璃体中地塞米松峰值浓度估计分别比球周注射5mg磷酸地塞米松钠和口服7.5mg地塞米松高3倍和12倍。因此，结膜下注射是向眼的前段和后段输送地塞米松的最有效方法。全身药物吸收相当可观，与球周注射后的吸收程度相当。
