Degarelix is a GnRH antagonist used in advanced prostate cancer. It directly blocks the gonadotrophin-releasing hormone receptor, rapidly reducing testosterone without the initial flare seen with GnRH agonists. It is given by subcutaneous injection, usually once a month, under specialist supervision.
Also known as: Degarelix, Firmagon
Degarelix + amiodarone: risk of QT interval prolongation — evaluate the combination carefully.
The Prontuário documents for degarelix that "concomitant use with drugs that prolong the QTc interval should be carefully evaluated (e.g. class Ia and III antiarrhythmics, methadone, moxifloxacin and some antipsychotics)". Amiodarone, a class III antiarrhythmic, prolongs the QT interval in a well-known manner and adding it to degarelix increases the risk of ventricular arrhythmias, including torsades de pointes. The risk is higher in patients with prolonged baseline QT, hypokalaemia, hypomagnesaemia, advanced age or renal/hepatic impairment. If the combination is unavoidable, monitor the ECG and electrolytes and prefer the shortest possible duration; any syncope or palpitation must be assessed urgently.
Degarelix + amiodarone: assess QT prolongation risk — prefer an alternative if possible.
The Prontuário documents for degarelix: "Concomitant use with drugs that prolong the QTc interval should be carefully evaluated (e.g. class Ia and III antiarrhythmics...)". Amiodarone (class III) prolongs QT and the combination adds arrhythmia risk (torsades de pointes).
ECG and electrolytes (potassium, magnesium) before and during the combination in at-risk patients.
Syncope, palpitations, dizziness or prolonged QT on ECG during the combination.
Assess individual risk (baseline QT, electrolytes, age, renal/hepatic function); prefer alternatives without QT effect when possible; if unavoidable, monitor the ECG.
DailyMed/FDA (NIH/NLM) — approved Degarelix label (FIRMAGON): https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=ab11dd8a-0fd9-4013-89ab-e114557c7e4b ; approved Amiodarone label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=51a88e8e-da02-4b97-9e7e-442fbffd908d ; Prontuário Terapêutico do INFARMED (11th ed., 2012) — Degarelix, 16.2.2.5
Degarelix + moxifloxacin: risk of QT interval prolongation — evaluate the combination carefully.
The Prontuário explicitly cites moxifloxacin among the drugs whose combination with degarelix should be "carefully evaluated" because of the QTc prolongation risk. Moxifloxacin is among the fluoroquinolones with the greatest effect on the QT interval, and adding it to degarelix increases the risk of ventricular arrhythmias. In patients with advanced prostate cancer and respiratory or urinary infection, prefer an antibiotic without QT effect when an alternative exists; if moxifloxacin is unavoidable, use the shortest course, monitor ECG and electrolytes in at-risk patients and watch for syncope, palpitations or dizziness.
Degarelix + moxifloxacin: avoid if possible — risk of QT prolongation (moxifloxacin is cited in the Prontuário).
The Prontuário documents the precaution with QT-prolonging drugs for degarelix, explicitly citing moxifloxacin ("e.g. ... moxifloxacin and some antipsychotics"). Moxifloxacin is among the fluoroquinolones with the greatest QT effect — adding it to degarelix increases arrhythmia risk.
ECG and electrolytes in at-risk patients during the combination.
Syncope, palpitations, dizziness or prolonged QT on ECG.
Avoid the combination if possible; if unavoidable (infection without alternative), monitor ECG and electrolytes and use the shortest antibiotic course.
DailyMed/FDA (NIH/NLM) — approved Degarelix label (FIRMAGON): https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=ab11dd8a-0fd9-4013-89ab-e114557c7e4b ; approved Moxifloxacin label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=1ed191f5-7df5-488c-bb72-91ac0b618d9a ; Prontuário Terapêutico do INFARMED (11th ed., 2012) — Degarelix, 16.2.2.5
No documented food or drink interactions.
The Prontuário documents that degarelix may cause QT interval prolongation in the long term; combination with QT-prolonging drugs should be carefully evaluated.
Assess individual risk (baseline QT, electrolytes); monitor ECG in at-risk patients and with QT-prolonging drugs.
Prontuário Terapêutico do INFARMED (11th ed., 2012) — Degarelix, 16.2.2.5
Patients with severe liver dysfunction have not been studied — caution with use (label: "Patients with severe liver or kidney dysfunction have not been studied and caution is therefore warranted").
Use with caution in severe hepatic disease and monitor transaminases.
DailyMed/FDA (NIH/NLM) — approved Degarelix label (FIRMAGON): https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=ab11dd8a-0fd9-4013-89ab-e114557c7e4b
Patients with severe renal dysfunction have not been studied — caution with use (label).
Use with caution in severe renal impairment.
DailyMed/FDA (NIH/NLM) — approved Degarelix label (FIRMAGON): https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=ab11dd8a-0fd9-4013-89ab-e114557c7e4b
Safety and efficacy in women not established (indication exclusively male — prostate cancer); animal data show fetal risk.
Not applicable in pregnancy (indication exclusively male).
Male indication; not relevant during lactation.
Not applicable.
DailyMed/FDA (NIH/NLM) — approved Degarelix label (FIRMAGON): https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=ab11dd8a-0fd9-4013-89ab-e114557c7e4b
Clinical and educational support tool. The information does not replace a medical prescription or the opinion of a qualified healthcare professional.
GnRH receptor antagonist that rapidly suppresses testosterone to castration levels without the initial flare seen with agonists.
Competitive and reversible blockade of the GnRH receptor in the anterior pituitary, with immediate suppression of LH and FSH release and consequent fall in testosterone; it is not a CYP450 substrate, inducer or inhibitor.
Forms a depot at the subcutaneous injection site, with slow continuous release into the circulation ("FIRMAGON forms a depot upon subcutaneous administration, from which degarelix is released to the circulation").
Not metabolised by CYP450 in a clinically relevant manner (clinically significant pharmacokinetic interactions unlikely — label); it is a synthetic decapeptide degraded by peptidases.
Half-life of approximately 53 days ("half-life of approximately 53 days"), a consequence of the slow release from the subcutaneous depot; protein binding of ~90% ("protein binding of degarelix is estimated to be approximately 90%").
