title: Efficacy of Low-Dose Chlorthalidone and Hydrochlorothiazide as Assessed by 24-h Ambulatory Blood Pressure Monitoring.
abstract: BACKGROUND
  Thiazide and thiazide-like diuretic agents are being increasingly used at lower doses. Hydrochlorothiazide (HCTZ) in the 12.5-mg dose remains the most commonly prescribed antihypertensive agent in the United States.
  
  
  OBJECTIVE
  This study compared chlorthalidone, 6.25 mg daily, with HCTZ, 12.5 mg daily, by 24-h ambulatory blood pressure (ABP) monitoring and evaluated efficacy. Because HCTZ has been perceived as a short-acting drug, a third comparison with an extended-release formulation (HCTZ-controlled release [CR]) was added.
  
  
  METHODS
  This 12-week comparative, double-blind, outpatient study randomized 54 patients with stage 1 hypertension to receive either chlorthalidone, 6.25 mg, (n = 16); HCTZ 12.5 mg (n = 18); or HCTZ-CR 12.5 mg (n = 20). ABP monitoring was performed at baseline and after 4 and 12 weeks of therapy.
  
  
  RESULTS
  All 3 treatments significantly (p < 0.01) lowered office BP at weeks 4 and 12 from baseline. At weeks 4 and 12, significant reductions in systolic and diastolic 24-h ambulatory and nighttime BP (p < 0.01) were observed with chlorthalidone but not with HCTZ. At weeks 4 (p = 0.015) and 12 (p = 0.020), nighttime systolic ABP was significantly lower in the chlorthalidone group than in the the HCTZ group. With HCTZ therapy, sustained hypertension was converted into masked hypertension. In contrast to the HCTZ group, the HCTZ-CR group also showed a significant (p < 0.01) reduction in 24-h ABP. All 3 treatments were generally safe and well tolerated.
  
  
  CONCLUSIONS
  Treatment with low-dose chlorthalidone, 6.25 mg daily, significantly reduced mean 24-h ABP as well as daytime and nighttime BP. Due to its short duration of action, no significant 24-h ABP reduction was seen with HCTZ, 12.5 mg daily, which merely converted sustained hypertension into masked hypertension. Thus, low-dose chlorthalidone, 6.25 mg, could be used as monotherapy for treatment of essential hypertension, whereas low-dose HCTZ monotherapy is not an appropriate antihypertensive drug. (Comparative Evaluation of Safety and Efficacy of Hydrochlorothiazide CR with Hydrochlorothiazide and Chlorthalidone in Patients With Stage I Essential Hypertension; CTRI/2013/07/003793).
authors.affiliation: Medical Affairs and Clinical Research, Ipca Laboratories Limited, Mumbai, India.
authors.forename: Anil K
authors.initials: AK
authors.lastname: Pareek
authors.affiliation: Department of Cardiology, Mount Sinai Health Medical Center, Icahn School of Medicine, New York, New York; Department of Cardiology University Hospital, Bern, Switzerland. Electronic address: messerli.f@gmail.com.
authors.forename: Franz H
authors.initials: FH
authors.lastname: Messerli
authors.affiliation: Clinical Research and Development, Ipca Laboratories Limited, Mumbai, India.
authors.forename: Nitin B
authors.initials: NB
authors.lastname: Chandurkar
authors.affiliation: Clinical Research and Development, Ipca Laboratories Limited, Mumbai, India.
authors.forename: Shruti K
authors.initials: SK
authors.lastname: Dharmadhikari
authors.affiliation: Department of Medicine, King Edward Memorial Hospital, Pune, India.
authors.forename: Anil V
authors.initials: AV
authors.lastname: Godbole
authors.affiliation: Department of Medicine, Rajiv Gandhi Medical College and Chhatrapati Shivaji Maharaj Hospital, Kalwa, Thane, India.
authors.forename: Prasita P
authors.initials: PP
authors.lastname: Kshirsagar
authors.affiliation: Medilink Hospital and Research Centre, Ahmadabad, India.
authors.forename: Manish A
authors.initials: MA
authors.lastname: Agarwal
authors.affiliation: Dr. Kamal Sharma Cardiology Clinic, Ahmadabad, India.
authors.forename: Kamal H
authors.initials: KH
authors.lastname: Sharma
authors.affiliation: Department of Medicine, Dr. Sampurnanand Medical College and Mathura Das Mathur Hospital, Jodhpur, India.
authors.forename: Shyam L
authors.initials: SL
authors.lastname: Mathur
authors.affiliation: Omega Hospital, Mangalore, India.
authors.forename: Mukund M
authors.initials: MM
authors.lastname: Kumbla
mesh_terms: D000328:Adult; D000959:Antihypertensive Agents; D001794:Blood Pressure / Q000187:drug effects*; D018660:Blood Pressure Monitoring, Ambulatory; D002752:Chlorthalidone / Q000008:administration & dosage*; D004232:Diuretics / Q000008:administration & dosage; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004359:Drug Therapy, Combination; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006852:Hydrochlorothiazide / Q000008:administration & dosage*; D006973:Hypertension / Q000188:drug therapy* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D016896:Treatment Outcome
chemical_list: D000959:Antihypertensive Agents; D004232:Diuretics; D006852:Hydrochlorothiazide; D002752:Chlorthalidone
keywords: hypertension; low-dose diuretic agent; thiazide