Hypertension Knowledge Centre
Centrally Acting Drugs
Dose-response of moxonidine
A number of controlled clinical trials started dosing with 0.2mg/day and allowed doubling of this dosage after two weeks if there was insufficient response.20,21,26,27 The percentage of patients taking 0.4mg/ day is shown in figure 7, which demonstrates that 10-56% of patients needed the higher dosage.
Figure 7: Percentage of patients requiring a doubling of the initial dose from 0.2mg to 0.4mg daily after two weeks of treatment in some clinical trials.20,21,26,27
Prichard et al (2003)25 examined the dose-relationship for moxonidine across the range of currently approved dosages (0.2-0.6 mg/day) using data from three placebo-controlled, doubleblind, comparative studies versus enalapril23-25 (read more here).
The three studies were based on a standardised protocol involving eight weeks of double-blind treatment, with a primary efficacy variable of office sitting diastolic blood pressure at trough. Patients enrolled in the three studies were broadly similar in their baseline demographics.
As previously described, the blood pressure responses to moxonidine and dose-matched enalapril were statistically significantly greater than placebo in all three trials (p<0.001), and there was no significant difference between the active drugs. There was a clear dose-linearity in the office sitting DBP response to moxonidine (figure 8). The evidence of a dose-proportionate effect was confirmed by analysis of ABPM measurements.
Figure 8: Dose-response of moxonidine in reducing office sitting diastolic blood pressure at trough from three randomised, double-blind, placebo controlled trials. Adapted from 25
The authors commented that the linear dose-response indicates that dose titration is a practical option with moxonidine, making it a useful and flexible agent for monotherapy or in combination with other antihypertensive drugs.