Hyponatraemia: demeclocycline had no clear effect on psychotic patients.

Clinical bottom line (level 1b-)

  1. Psychotic patients with polydypsia-hyponatraemia who were given demeclocycline had no clear difference in mean sodium level than those given placebo.
Alexander et al: Biological Psychiatry 1991; 30: 417-420
Expires January 2004

The study

Double-blinded ?concealed randomised cross-over trial with intention-to-treat
Setting: neuropsychiatric research hospital, USA

9 patients (aged range 31 to 47 years; mean 38, 67% male) chronic psychiatric illness and documented episodic or chronic hyponatraemia (serum sodium <135 mEq/L) associated with polydipsia
Control Group: (n = 9, 9 analysed): placebo followed by active drug
Experimental Group: (n = 9, 9 analysed): demeclocycline 300 mg two times a day for 7 days, 300 mg three times a day for 7 days and finally 300 mg four times a day for 7 days, followed by three weeks of placebo
Patients were kept on a stable dose of neuroleptics throughout the study.
100% followed for 8 weeks

The evidence

Outcome Control Group
(SD)		 Experimental Group
(SD)		 Mean Difference
(95% CI)
mean sodium (over all three weeks) 132.7
() 		133.8
() 		-1.10
( to )

  • Confidence intervals for the mean sodium level could not be determined as no standard deviation was stated. As the difference between the means was so small, the confidence interval would almost certainly cross zero.

    • Comments

    1. The trial was too small to show any clear difference in sodium levels between the two groups.
    2. It is unclear how representative the sample was of psychiatric patients. The subjects mental state was not assessed by standardised instruments but they may have been a particularly ill group as many had been long-term inpatients.

    Citation

    1. Alexander RC, Karp BI, Thompson S, et al: A double blind, placebo-controlled trial of demeclocycline treatment of polydipsia-hyponatraemia in chronically psychotic patients. Biological Psychiatry 1991; 30: 417-420
    Contributor: Clare Wotton and Musab Hayatli, January 2000
    Reviewer: Steve Kisely

    Clinical Question.
    Patient psychotic
    Intervention or Exposure demeclocycline
    Comparison placebo
    Outcome sodium levels