Wing L M, Reid J L, Davies D S, Dargie H J, Dollery C T
Br Med J. 1977 Jan 15;1(6054):136-8. doi: 10.1136/bmj.1.6054.136.
Clonidine failed to reduce the blood pressures of two patients with essential hypertension. On was given 5-4 mg/day and the other 6 mg/day, and their respective peak plasma clonidine concentrations were 26-2 ng/ml and 14-4 ng/ml. Several months after the end of clonidine treatment a single oral dose of 0-3 mg of clonidine produced maximum falls in blood pressure of 30/22 mm Hg and 88/41 mm Hg with peak plasma clonidine concentrations of 1-4 ng/ml and 0-9 ng/ml. Resistance to the hypotensive effect of high doses of clonidine may be due to stimulation of peripheral alpha-adrenoceptors causing vasoconstriction, which maintains a raised blood pressure.
可乐定未能降低两名原发性高血压患者的血压。一名患者给予5 - 4毫克/天，另一名患者给予6毫克/天，他们各自的可乐定血浆峰值浓度分别为26 - 2纳克/毫升和14 - 4纳克/毫升。可乐定治疗结束数月后，单次口服0 - 3毫克可乐定，血压最大降幅分别为30/22毫米汞柱和88/41毫米汞柱，可乐定血浆峰值浓度分别为1 - 4纳克/毫升和0 - 9纳克/毫升。对高剂量可乐定降压作用的抵抗可能是由于外周α - 肾上腺素能受体受刺激导致血管收缩，从而维持血压升高。
