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Cialis (Tadalafil) Metabolism and Energy Expenditure: What the Evidence Actually Shows

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At a glance

  • Main pathway / CYP3A4; the catechol metabolite is not expected to be pharmacologically active [1]
  • Half-life / mean 17.5 hours [1]
  • Time to peak / 30 minutes to 6 hours, median 2 hours [1]
  • Food effect / none on the rate or extent of absorption [1]
  • Steady state / within 5 days; exposure about 1.6-fold that of a single dose [1]
  • Approved uses / ED, BPH signs and symptoms, and both together [1][2]

How tadalafil is absorbed and cleared

Cialis reaches peak plasma concentration between 30 minutes and 6 hours after a dose, with a median of 2 hours, and food does not influence the rate or extent of absorption [1]. Tadalafil is metabolized mainly by CYP3A4 to a catechol metabolite, and the metabolites are not expected to be pharmacologically active [1]. Oral clearance is about 2.5 L/h, and about 61% of a dose is excreted in feces and 36% in urine as metabolites [1]. Once-daily dosing reaches steady state within 5 days, with exposure about 1.6-fold that of a single dose [1].

Tadalafil does not inhibit or induce the CYP enzymes listed in the Cialis label (CYP1A2, 3A4, 2C9, 2C19, 2D6 and 2E1), and the label says Cialis is not expected to cause clinically significant inhibition or induction of the clearance of drugs metabolized by those enzymes [1].

Is Cialis a metabolism or weight drug?

No. Cialis is indicated for erectile dysfunction, for the signs and symptoms of BPH, and for both conditions together. A weight or metabolic indication is not among them [1][2].

What changes tadalafil levels

Ketoconazole 400 mg daily raised tadalafil 20 mg AUC by 312% (peak 22%), and rifampin 600 mg daily cut tadalafil 10 mg AUC by 88% (peak 46%) [1]. The Cialis label caps as-needed tadalafil at 10 mg every 72 hours with strong CYP3A4 inhibitors and once-daily use at 2.5 mg; with inducers it calls for no dose adjustment but notes once-daily efficacy may fall by an unknown amount [1].

Frequently asked questions

Does Cialis boost metabolism or burn fat?
Cialis is approved for erectile dysfunction, BPH and ED with BPH, not for weight or metabolic treatment [1][2]. Its label does not list fat burning or increased energy expenditure as a use.
What enzyme breaks down tadalafil?
CYP3A4, mainly; the catechol metabolite is not expected to be pharmacologically active [1]. Ketoconazole 400 mg daily raised tadalafil 20 mg exposure by 312%, and rifampin 600 mg daily cut tadalafil 10 mg exposure by 88% [1].
How long does tadalafil stay in the body?
Mean terminal half-life is 17.5 hours in healthy subjects [1]. The label links this long half-life to interactions that last longer than with sildenafil, whose half-life is about 4 hours, and it contraindicates nitrates with Cialis. In a life-threatening emergency, it says a nitrate may be considered at least 48 hours after the last Cialis dose, only under close medical supervision with hemodynamic monitoring [1].

References

  1. U.S. National Library of Medicine, DailyMed. Cialis (tadalafil) tablets, Lilly prescribing information. Cialis (tadalafil) tablets, Lilly label
  2. Drugs@FDA: FDA-Approved Drugs. Drugs@FDA: FDA-Approved Drugs
Evidence overview for cialis tadalafil: Cialis (Tadalafil) Metabolism and Energy Expenditure: What the Evidence Actually Shows