The effect was similar to that obtained when thiazides are used as a single agent .
Thiazides when given as a second-line drug have a dose related effect to lower blood pressure that is similar to when they are added as a first-line drug .
This means that the BP lowering effect of thiazides is additive .
Loop diuretics appear to have a similar blood pressure lowering effect as thiazides at 1 times the recommended starting dose .
Because of the short duration of the trials and lack of reporting of adverse events , this review does not provide a good estimate of the incidence of adverse effects of diuretics given as a second-line drug
BACKGROUND Diuretics are widely prescribed for hypertension not only as a first-line drug but also as a second-line drug .
Therefore , it is essential to determine the effects of diuretics on blood pressure ( BP ) , heart rate and withdrawals due to adverse effects ( WDAEs ) when given as a second-line drug .
Low-dose atenolol-chlorthalidone combination for treatment of mild hypertension.
In a r and omized , double-blind , within-patient study , 28 out- patients with mild to moderate hypertension were given , at the end of a 3-week placebo wash-out period , four different antihypertensive treatments for 3 weeks each . the treatments were 50 mg atenolol , 100 mg atenolol , 12.5 mg chlorthalidone and a fixed combination of 50 mg atenolol and 12.5 mg chlorthalidone . All treatments were given once daily . Visits were scheduled for the last day of each treatment period , 24 - 26 hours after the last dose , and there was an intermediary wash-out period between each pair of active treatments . Supine systolic/diastolic blood pressure was 165/102 on placebo , 153/93 mmHg on 50 mg atenolol , 155/91 mmHg on 100 mg atenolol , 148/93 mmHg on 12.5 mg chlorthalidone and 144/89 mmHg on the combination . All the changes in pressure were significant ( p less than 0.01 ) versus placebo .  Supine systolic blood pressure was lower on the combination than on 100 mg atenolol alone ( p less than 0.05 ) and upright systolic pressure was lower on the combination than on 100 mg atenolol ( p less than 0.05 ) or 50 mg atenolol ( p less than 0.05 ) alone . The heart rate was lowered by atenolol alone or combined with chlorthalidone but did not fall below 56 bpm in any patient . Serum potassium levels were lower on 12.5 mg chlorthalidone than on placebo ( 3.88 mEq/l vs 4.09 mEq/l -- p less than 0.05 ) but the difference was trivial ; on the combination of atenolol-chlorthalidone there was no significant difference versus placebo ( 3.97 mEq/l vs 4.09 mEq/l -- NS ) . ( ABSTRACT TRUNCATED AT 250 WORDS
The effect was similar to that obtained when thiazides are used as a single agent .
Thiazides when given as a second-line drug have a dose related effect to lower blood pressure that is similar to when they are added as a first-line drug .
This means that the BP lowering effect of thiazides is additive .
Loop diuretics appear to have a similar blood pressure lowering effect as thiazides at 1 times the recommended starting dose .
Because of the short duration of the trials and lack of reporting of adverse events , this review does not provide a good estimate of the incidence of adverse effects of diuretics given as a second-line drug
BACKGROUND Diuretics are widely prescribed for hypertension not only as a first-line drug but also as a second-line drug .
Therefore , it is essential to determine the effects of diuretics on blood pressure ( BP ) , heart rate and withdrawals due to adverse effects ( WDAEs ) when given as a second-line drug .