The Therapeutics Initiative presents critically appraised summary evidence primarily from controlled drug trials. Such evidence applies to patients similar to those involved in the trails, and may not be generalizable to every patient. We are committed to evaluate the effectiveness of our educational activities using the Pharmacare/PharmaNet databases without identifying individual physicians, pharmacies or patients. The Therapeutics Initiative is funded by the BC Ministry of Health through a 5-year grant to the University of BC. The Therapeutics Initiative provides evidence based advice about drug therapy, and is not responsible for formulating or adjudicating provincial drug policies. 

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Therapeutics Letter, issue 44, Feb - May 2002

New Drugs VII 

Mirtazapine (Remeron®)

Approved indication: “Symptomatic relief of depressive illness.” 1

Mechanism of action:  

As with all antidepressants the mechanism of therapeutic benefit is unknown. It is an inhibitor of a number of receptors including adrenergic, serotonergic, histaminic and muscarinic. It is classified as an atypical antidepressant and is unrelated to tricyclics, selective serotonin reuptake inhibitors or monoamine oxidase inhibitors.

Pharmacokinetics: Mirtazapine is inactivated by liver metabolism. Mean half-life is 26 hours for men and 37 hours for women; half-life is prolonged in the elderly and in the presence of liver and renal disease.1

Evidence of efficacy: The effectiveness of mirtazapine for use longer than 6 weeks has not been systematically evaluated in controlled clinical trials. The one longer-term study only followed a subset of treatment responders, invalidating randomization and thus interpretation.2 Two randomized controlled trials (RCT) claim an advantage for mirtazapine 3, 4 and one does not. 5  Twelve randomized controlled trials 5-18 and three meta-analyses 19-21 evaluated mirtazapine compared to other antidepressants, including amitriptyline, clomipramine, doxepin, trazodone, paroxetine, citalopram and fluoxetine.  The main efficacy measure was symptomatic improvement as indicated by a ≥ 50% reduction from baseline in the Hamilton Depression Rating Scale (HAM-D) or by a score of ≤ 7, signifying remission of depression. Between 20-40% of patients in these 5-6 week trials were lost to follow-up, weakening the validity of study results, and no consistent advantage or disadvantage was observed for mirtazapine. Doses of mirtazapine and comparators varied considerably between trials.

Adverse effects: The common and serious adverse effects (from the product monograph) expressed as absolute risk increase over placebo are as follows: somnolence 36%, increased appetite 15%, dry mouth 10%, weight gain 10%, elevated cholesterol 8%, constipation 6%, dizziness 4%, liver enzyme elevations (ALT >3 times normal) 2%, neutropenia 1.5%, mania/hypomania 0.2%, agranulocytosis 0.07%, and seizure 0.03%. 1

Dose and cost: Approved dose is 15-45 mg/day  ($0.69 -$ 2.06/day).
The three least expensive antidepressants in B.C. are: amitriptyline (Elavil®, generic) 75-300 mg/day ($0.04 – $0.16/day), imipramine (Tofranil®, generic) 75-300 mg/day ($0.05 – $0.17/day) and trimipramine (Surmontil®, generic) 75-300 mg/day ($0.55 – $1.11/day).
The three most expensive antidepressants in B.C. are: sertraline (Zoloft®) 50-200 mg/day ($1.31 – $2.80/day), venlafaxine (Effexor®) 75-300 mg/day ($1.64 – $3.50/day) and paroxetine (Paxil®) 20-50 mg/day ($1.76 – $3.64/day).

Conclusion: Mirtazapine has no proven efficacy or safety advantage over other antidepressant therapies. It has a prominent sedative effect and patients should be warned that it may cause mental or motor impairment. Longer-term trials with adequate follow-up are needed.

Salmon-Calcitonin Nasal Spray (Miacalcin®)

Approved indication: “Treatment of diagnosed postmenopausal osteoporosis in females greater than 5 years postmenopause with low bone mass relative to healthy premenopausal females.” 22

Mechanism of action: Salmon-calcitonin inhibits bone resorption by reducing the activity of osteoclasts; it has 40-50 times more affinity for cell surface receptor binding sites than mammalian calcitonins. The mechanism of the acute analgesic effect of salmon-calcitonin is unknown. 23

Pharmacokinetics: The bioavailability of salmon-calcitonin nasal spray is 3-50% relative to intramuscular administration. The drug is rapidly absorbed by the nasal mucosa. The elimination half-life is about 45 minutes. 22

Evidence of efficacy: Two RCTs have assessed the efficacy of salmon calcitonin nasal spray on the rates of vertebral collapse (radiographically-detected) and non-vertebral fractures in postmenopausal women with bone mineral density (BMD) levels 2 standard deviations or more below mean values of 30 year old women. 24, 25 The first RCT, a 2-year dose-response study, had a sample size too small to detect differences in fracture rates.
The PROOF study was a 5-year study that randomized participants with at least one vertebral collapse at baseline to receive 100, 200 or 400 IU of salmon-calcitonin, or placebo. The primary endpoint was the incidence of new vertebral collapse compared to placebo. In 817 patients with vertebral fractures at baseline and follow-up radiographs, 21.3% taking 200 or 400 IU salmon calcitonin vs. 29.6% taking placebo experienced ≥ 1 new collapse (RR 0.72 [0.54-0.96], ARR 8.3%, NNT = 12 for 3 years). There was no effect of the drug on non-vertebral or symptomatic fractures. Fifty-nine percent of the 1255 participants withdrew from the study prematurely.

Adverse effects: Rhinitis (nasal congestion, nasal discharge, or sneezing) occurred in 22% of participants receiving salmon-calcitonin vs. 15% of placebo participants in the PROOF study (ARI 7%).

Dose and cost: The recommended dose is 200 IU (one spray) daily ($1.48/day). Nostrils are to be alternated. It should be taken in conjunction with at least 1000 mg elemental calcium per day and 400 IU vitamin D per day. Other drugs for the same indication are: etidronate (Didrocal®) one tablet daily ($0.43/day), alendronate (Fosamax®) 10 mg daily ($1.84/day), risedronate (Actonel®) 5 mg daily ($1.93/day), raloxifene (Evista®) 60 mg daily ($1.69/day).

Conclusion: Salmon-calcitonin nasal spray reduces radiographically-detected new vertebral collapse in patients with at least one vertebral collapse and low BMD (ARR 8.3%), but has no effect on non-vertebral fractures. Long term compliance is poor, even in a trial setting.

Gatifloxacin (Tequin®) and Moxifloxacin (Avelox®)

Approved indications for both: “acute sinusitis, community-acquired pneumonia (CAP) and acute exacerbation of chronic bronchitis (AECB). 26, 27 Additional indications for gatifloxacin are uncomplicated and complicated UTI, pyelonephritis and uncomplicated gonorrhoea.” 26

Mechanism of action: similar to other fluroquinolone antibiotics.

Pharmacokinetics: Both are well absorbed with half-lives of 12 hours. Gatifloxacin is eliminated by the kidney and moxifloxacin is metabolized by the liver. 26, 27

Evidence of effectiveness: Gatifloxacin has been compared with other antibiotics in 9 double blind RCTs. Eight of these trials show clinical efficacy ranging from 88 to 98%, which was not different from levofloxacin, ofloxacin, clarithromycin and erythromycin in the treatment of acute sinusitis, CAP, AECB, UTI and gonorrhoea. 28-35 In one trial, gatifloxacin was significantly more effective than cefuroxime axetil (ARR 12%) in the treatment of AECB. 36
Moxifloxacin has been compared with other antibiotics in 10 double blind RCTS. These trials show clinical efficacy for the treatment of acute sinusitis, CAP and AECB ranging from 88 to 97%, which was similar to levofloxacin, cefuroxime axetil, clarithromycin, amoxicillin, or azithromycin (87 to 95%). 37-48

Adverse effects: Gatifloxacin and moxifloxacin have tolerability profiles similar to other fluroquinolones. Adverse effects include: gastrointestinal upset [nausea, diarrhoea, vomiting and abdominal pain], headache, and dizziness. Adverse effects reported since marketing are ventricular tachycardia, renal failure, peripheral neuropathy, myositis, and tendonitis. 26, 27

Dose and cost: Gatifloxacin (Tequin®), 400mg once daily ($5.36/day), Moxifloxacin (Avelox®), 400mg once daily ($5.36/day), ciprofloxacin (Cipro®) 250 to 500 mg BID ($4.76 – 5.40/day) ofloxacin* (Floxin®, generic) 400 mg BID ($3.81/day) levofloxacin* (Levaquin®), 250 to 500 mg daily ($4.85 – 5.52/day). *See Therapeutics Letter #26.

Conclusion: Gatifloxacin and moxifloxacin have no proven clinical advantages over other fluroquinolones, macrolides or amoxicillin. Based on cost they are not first choice drugs for their approved indications.


RR=Relative Risk

ARR=Absolute Risk Reduction

NNT=Number Needed to Treat to prevent one event

ARI=Absolute Risk Increase

This Therapeutics Letter contains an assessment and synthesis of published (and whenever possible peer-reviewed) publications up to March, 2002. We attempt to maintain the accuracy of the information contained in the Therapeutics Letter by extensive literature searches and verification by both the authors and the editorial board. In addition this Therapeutics Letter was submitted for review to 50 experts and primary care physicians in order to correct any identified shortcomings or inaccuracies and to ensure that the information is concise and relevant to clinicians.


1.        Organon Ca nada. Remeron (Mirtazapine) Tablets. Antidepressant. Product Monograph. Ottawa : May 7, 2001

2.        Montgomery SA, Reimitz PE , Zivkov M. Mirtazapine versus amitriptyline in the long-term treatment of depression: a double-blind placebo-controlled study. Int Clin Psychopharmacol 1998; 13:63-73

3.        Khan MC. A randomized, double-blind placebo-controlled 5-weeks’ study of Org 3770 (mirtazapine) in major depression. Human Psychopharmacology 1995; 10(SUPPL. 2): S119-S124

4.        Claghorn JL, Lesem MD. A double-blind placebo-controlled study of Org 3770 in depressed outpatients. J Affect Disord 1995; 34:165-171

5.        Vartiainen H, Leinonen E. Double-blind study of mirtazapine and placebo in hospitalized patients with major depression. Eur Neuropsychopharmacol 1994; 4:145-150

6.        Smith WT, Glaudin V, Panagides J, Gilvary E. Mirtazapine vs. amitriptyline vs. placebo in the treatment of major depressive disorder. Psycopharmacol Bull 1990; 26:191-196

7.        Bremner JD, Smith WT. Org 3770 VS amitriptyline in the continuation treatment of depression: A placebo controlled trial. Eur J Psychiatr 1996; 10:5-15

8.        Halikas JA. Org 3770 (mirtazapine) versus trazodone: a placebo controlled trial in depressed elderly patients. Human Psychopharmacology 1995; 10:S125-S133

9.        Bruijn JA, Moleman P, Mulder PGH et al. A double blind, fixed blood-level study comparing mirtazapine with imipramine in depressed in-patients. Psychopharmacology (Berl) 1996; 127:231-237

10.     Hoyberg OJ, Maragakis B, Mullin J et al. A double-blind multicentre comparison of mirtazapine and amitriptyline in elderly depressed patients. Acta Psychiatr Scand 1996; 93:184-190

11.     Mullin J, Lodge A, Bennie E et al. A multicentre, double-blind, amitriptyline-controlled study of mirtazapine in patients with major depression. Journal of Psychopharmacol 1996; 10:235-240

12.     Richou H, Ruimy P, Charbaut J et al. A multicentre, double-blind, clomipramine-controlled efficacy and safety study of Org 3770. Human Psychopharmacology 1995; 10:263-271

13.     Zivkov M, De Jongh GD. Org 3770 versus amitriptyline: a 6-week randomized double-blind multicentre trial in hospitalized depressed patients. Human Psychopharmacology 1995; 10:173-180

14.     Marttila M, Jaaskelainen J, Jarvi R et al. A double-blind study comparing the efficacy and tolerability of mirtazapine and doxepin in patients with major depression. Eur Neuropsychopharmacol 1995; 5:441-446

15.     Benkert O, Szegedi A, Kohnen R. Mirtazapine compared with paroxetine in major depression. J Clin Psychiatry 2000; 61:656-663

16.     Leinone E, Skarstein J, Behnke K et al. Efficacy and tolerability of mirtazapine versus citalopram: a double-blind, randomized study in patients with major depressive disorder. Nordic Antidepressant Study Group. Int Clin Psychopharmacol 1999; 14:329-337

17.     Wheatley DP, van Moffaert M, Timmerman L, Kremer CM.  Mirtazapine: efficacy and tolerability in comparison with fluoxetine in patients with moderate to severe depressive disorder. J Clin Psychiatry 1998; 59:306-312

18.     van Moffaert M, de Wilde J, Vereecken A et al. Mirtazapine is more effective than trazodone: a double-blind controlled study in hospitalized patients with major depression. Int Clin Psychopharmacol 1995; 10:3-9

19.     Stahl S, Zivkov M, Reimitz PE et al. Meta-analysis of randomized double-blind placebo-controlled efficacy and safety studies of mirtazapine versus amitriptyline in major depression. Acta Psychiatr Scand Suppl 1997; 391:22-30

20.     Fawcett J, Barkin RL. A Meta-analysis of eight randomized double-blind controlled trials of mirtazapine for the treatment of patients with major depression and symptoms of anxiety. J Clin Psychiatry 1998; 59:123-127

21.     Zivkov M, Roes KCB, Pols AG. Efficacy of Org 3770 (mirtazepine) vs amitriptyline in patients with major depressive disorder: A meta-analysis. Human Psychopharmacology 1995; 10(SUPPL. 2): S135-S145.

22.     Novartis Pharmaceuticals. Synthetic calcitonin (Salmon) nasal spray (Miacalcin NS). Bone Metabolism Regulator.  Product Monograph. Ottawa, 2000.

23.     Lyritis GP, Paspati I, Karachalios T, et al. Pain relief from nasal salmon calcitonin in osteoporotic vertebral crush fractures: A double-blind, placebo-controlled clinical study. Acta Orthop Scand Suppl 1997; 275:112-114.

24.     Overgaard, K, Hansen, MA, Jensen, SB, Christiansen, C. Effect of salmon-calcitonin given intranasally on bone mass and fracture rates in established osteoporosis: a dose-response study. BMJ 1992; 305:556-561.

25.     Chesnut CH 3rd, Silverman S, Andriano KA. A randomized trial of nasal spray salmon calcitonin in postmenopausal women with established osteoporosis: the prevent recurrence of osteoporotic fractures study.  Am J Med 2000; 109:267-276.

26.     Gatifloxacin. (Tequin®) Fluoroquinolone antibiotic. Product Monograph.

27.     Moxifloxacin hydrochloride (Avelox®). Fluroquinolone antibiotic. Product Monograph.

28.     Fogarty C, McAdoo M, Paster RZ et al.  Gatifloxacin vs clarithromycin in the management of acute sinusitis. J Respir Dis 1999; 20(11 Suppl):S17-21.

29.     Sullivan JG, McEl roy AD, Honsinger RW. Treating community-acquired pneumonia with once-daily gatifloxacin vs once-daily levofloxacin. J Respir Dis 1999; 20(11 Suppl):S49-59.

30.     Ramirez JA, Nguyen T-H, Tellier G et al. Treating community-acquired pneumonia with once-daily gatifloxacin vs twice-daily clarithromycin. J Respir Dis 1999; 20(11 Suppl):S40-48.

31.     Fogarty C, Dowell M, Ellison WT et al. A comparison gatifloxacin and ceftriaxone/clarithromycin in the treatment of community acquired pneumonia requiring hospitalization. J Respir Dis 1999; 20(11 Suppl):S60-69.

32.     Saito A, Koike T, Takeichi K et al. A double blind comparative study of gatifloxacin and levofloxacin in pneumonia.  Japanese Journal of Chemotherapy 1999; 47:712-33.

33.     Gotfried MH, DeAbate CA, Fogarty C et al. Comparison of 5-day, short-course gatifloxacin therapy with 7-day gatifloxacin therapy and 10-day clarithromycin therapy for acute exacerbation of chronic bronchitis. Clin Ther. 2001; 23:97-107.

34.     Kawada Y, Ban Y, Kumamoto Y et al. Comparative study on gatifloxacin and levofloxacin in complicated urinary tract infections. Japanese Journal of Chemotherapy 1999; 47:662-679.

35.     Stoner BP, Douglas JM. Jr., Martin DH et al.  Single-dose gatifloxacin compared with ofloxacin for the treatment of uncomplicated gonorrhea: a randomized, double-blind, multicenter trial. Sex Transm Dis 2001; 28:136-142.

36.     DeAbate CA, McIvor RA, McElvaine P et al. Once-daily gatifloxacin vs twice-daily cefuroxime axetil in the treatment of acute exacerbations of chronic bronchitis. J Respir Dis 1999; 20(11 Suppl):S23-29.

37.     Siegert R, Gehanno P, Nikolaidis P et al. A comparison of the safety and efficacy of moxifloxacin (BAY 12-8039) and cefuroxime axetil in the treatment of acute bacterial sinusitis in adults. The Sinusitis Study Group. Respir Med 2000; 94:337-344.

38.     Burke T. Villanueva C, Mariano H. Jr. et al. Comparison of moxifloxacin and cefuroxime axetil in the treatment of acute maxillary sinusitis. Clin Ther 1999; 21:1664 – 1677.

39.     Hautamaki D. Bruya T. Kureishi A. et al.  Short-course (5-day) moxifloxacin versus 7-day levofloxacin therapy for treatment of acute exacerbations of chronic bronchitis. Today's Therapeutic Trends 2001; 19:117-136

40.     Anonymous. Moxifloxacin HCl compared with azithromycin for acute exacerbation of chronic bronchitis. Journal  Pharm Technol 2000; 16:161-162.

41.     Chodosh S., DeAbate A, Haverstock, et al. Short course of moxifloxacin therapy for treatment of acute bacterial exacerbations of chronic bronchitis. The Bronchitis Study group. Respir Med 2000; 94:18-27.

42.     DeAbate CA. Mathew CP. Warner JH. et al.  The safety and efficacy of short course (5-day) moxifloxacin vs. azithromycin in the treatment of patients with acute exacerbation of chronic bronchitis. Respir Med 2000;  94:1029-1037.

43.     Wilson R, Kubin R, Ballin I et al. Five-day moxifloxacin therapy compared with 7-day clarithromycin therapy for the treatment of acute exacerbation of chronic bronchitis. J Antimicrob Chemother 1999; 44 :501-513.

44.     File TM Jr. Larsen LS. Fogarty CM. et al.  Safety and efficacy of sequential (IV to PO) moxifloxacin for the treatment of community-acquired pneumonia in hospitalized patients. Today's Therapeutic Trends 2001;19: 251-270.

45.     Petitpretz P. Arvis P. Marel M. et al. Oral moxifloxacin vs high-dosage amoxicillin in the treatment of mild-to-moderate, community-acquired, suspected pneumococcal pneumonia in adults. Chest. 2001; 119:185-195.

46.     Hoeffken G. Meyer HP. Winter J. Verhoef L. The efficacy and safety of two oral moxifloxacin regimens compared to oral clarithromycin in the treatment of community-acquired pneumonia. Respir Med. 2001; 95:  553-564

47.     Patel T. Pearl J, Williams J et al. Efficacy and safety of ten-day moxifloxacin 400 mg once daily in the treatment of patients with community acquired pneumonia. Community Acquired Pneumonia Study Group. Respir Med. 2000; 94:97-105.

48.     Fogarty C, Grossman C. Williams J et al. Efficacy and safety of moxifloxacin vs clarithromycin for community acquired-pneumonia. Infect Med 1999; 16:748-763.

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