title: Guanfacine: effects of long-term treatment and withdrawal.
abstract: 1. Guanfacine 3-6 mg daily lowered blood pressure in five essential hypertensives and also reduced saliva production. 2. Plasma and urinary noradrenaline values were significantly reduced throughout the 8-10 weeks of treatment. 3. On substitution of placebo tablets for guanfacine, blood pressure increased over a 2-4 d period to reach but did not significantly exceed pretreatment levels. 4. After withdrawal of guanfacine plasma noradrenaline standing was significantly higher than the pretreatment level (P < 0.05) after 4 days. Saliva production was significantly higher than the pretreatment level on day 3 and day 4 of withdrawal. 5. Guanfacine is an effective antihypertensive drug with a spectrum of actions similar to clonidine. However, in abrupt withdrawal blood pressure returned to the pretreatment level over a 2-4 d period.
mesh_terms: D000959:Antihypertensive Agents / Q000008:administration & dosage / Q000097:blood / Q000627:therapeutic use; D001794:Blood Pressure / Q000187:drug effects; D005260:Female; D016316:Guanfacine; D006146:Guanidines / Q000008:administration & dosage / Q000627:therapeutic use*; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D006973:Hypertension / Q000188:drug therapy; D006993:Hypnotics and Sedatives / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D009638:Norepinephrine / Q000097:blood / Q000652:urine; D010648:Phenylacetates / Q000008:administration & dosage / Q000627:therapeutic use*; D011187:Posture; D012472:Salivation / Q000187:drug effects; D013375:Substance Withdrawal Syndrome / Q000503:physiopathology*; D013997:Time Factors
chemical_list: D000959:Antihypertensive Agents; D006146:Guanidines; D006993:Hypnotics and Sedatives; D010648:Phenylacetates; D016316:Guanfacine; D009638:Norepinephrine