Inderal (Propranolol). Dosage, Side Effects, Interactions
Inderal (Propranolol) is an active ingredient from the group of beta blockers and class II antiarrhythmics and is used to treat cardiovascular diseases, especially high blood pressure (hypertension) and cardiac arrhythmias. It is the oldest clinical representative of beta-blockers.
Inderal (Propranolol) is used in the treatment of cardiovascular diseases, especially high blood pressure ( hypertension ), coronary artery disease (CHD) or tachycardia cardiac arrhythmia, in order to lower high blood pressure and normalize the heartbeat.
Other indications for propranolol are primary anxiety syndrome, migraine prophylaxis, essential tremor and hyperthyroidism .
Propranolol is available for oral administration in the form of film-coated tablets, slow-release tablets or as a solution and for parenteral preparation in the form of ampoules.
The film-coated tablets should be swallowed whole before meals and the prolonged-release tablets (in the morning) with sufficient liquid. The oral solution should be administered directly into the child’s mouth during or immediately after a meal using a graduated oral syringe to prevent the risk of hypoglycaemia.
The intravenous injection should be given slowly, corresponding to 1 ml injection solution per minute, with continuous monitoring of pulse, blood pressure and ECG. The solution for injection should only be used until the cardiac arrhythmias are under control. Therapy with oral dosage forms should be resumed as soon as possible.
How Inderal (Propranolol) works
Propranolol belongs to the group of non-cardioselective beta-adrenoceptor antagonists, also known as beta- blockers . Blood pressure in the vascular system is regulated by various endogenous substances, including the stress hormones adrenaline and noradrenaline.
Propranolol inhibits the effects of adrenaline and noradrenaline by binding to the receptors for these messenger substances and blocking them. This reduces blood pressure and heart rate and relieves the heart. Propranolol takes effect after a few hours at the earliest.
After oral administration, more than 90% of propranolol is absorbed from the gastrointestinal tract, with the bioavailability being 34 – 46%. Propranolol is subject to a pronounced “first-pass effect”. Maximum plasma levels are reached after about 1-2 hours. The plasma protein binding is about 90%, the relative volume of distribution is 3.6 l/kg. When propranolol is broken down in the liver, the metabolite 4-hydroxypropranolol is formed, which also has a beta-blocking effect, but in a low concentration and half-life. More than 90% (<1% unchanged) of propranolol and its metabolites are eliminated via the kidneys. The elimination half-life is between 3 and 4 hours.
Dosage of Inderal (Propranolol)
- Initially, 80-120 mg propranolol hydrochloride per day, divided into two to three single doses as film-coated tablets, is recommended.
- If this does not achieve a sufficient effect, the daily dose can be increased to 160-240 mg propranolol hydrochloride, divided into two to three individual doses as film-coated tablets or 160 mg propranolol hydrochloride prolonged-release capsules once in the morning.
- If necessary, the dosage can be increased to 320 mg propranolol hydrochloride in two divided doses as a film-coated tablet or one single dose in the morning as a prolonged-release capsule.
Coronary heart disease, tachycardia arrhythmias
- The starting dose is 120 mg propranolol hydrochloride divided into three divided doses.
- If necessary, the daily dose can be increased to 160-240 mg propranolol hydrochloride, divided into two to three single doses as film-coated tablets or 160 mg propranolol hydrochloride prolonged-release capsules once in the morning or in the evening. The optimal maintenance dose must be adjusted individually.
- Treatment should be started between days 5 and 21 after myocardial infarction 120 mg propranolol hydrochloride divided into three single doses over 2-3 days.
- The therapy can then be continued with 80-160 mg propranolol hydrochloride divided into two to three single doses in the form of film-coated tablets or in a single dose in the form of prolonged-release capsules.
Hyperkinetic heart syndrome (so-called functional heart problems)
- The recommended dose is 30-120 mg propranolol hydrochloride) in three divided doses.
Essential tremor, migraine prophylaxis, symptomatic therapy of primary anxiety syndrome
- The usual starting dose is 80-120 mg propranolol hydrochloride divided into two to three doses. The dosage and the dosage interval are to be determined individually.
Hyperthyroidism (symptomatic therapy as an adjunct or until specific measures take effect)
- The recommended dose is 30-160 mg propranolol hydrochloride divided into three to four doses.
Arrhythmias in children and adolescents
- The dosage is to be determined individually. The orientation dose is 0.25 – 0.5 mg/kg body weight three to four times a day.
- The maximum dose per day is 1 mg/kg body weight four times a day, a dose of 160 mg propranolol hydrochloride per day must not be exceeded.
Impaired liver or kidney function
- If the liver or kidney function is severely impaired, the elimination of propranolol is reduced. A dose reduction may be necessary.
Proliferative infantile hemangiomas requiring systemic therapy:
- Therapy should be started in infants between the ages of 5 weeks and 5 months.
- The initial dose for the first week is 0.5 mg/kg propranolol (base) twice a day.
- There should be a gap of at least 9 hours between the individual doses.
- The dose increase up to the therapeutic dose should only be done under medical supervision.
- In the second week, 1 mg/kg twice a day and from the third week twice a day, 1.5 mg/kg is recommended as a maintenance dose.
- If you spit it out, vomit or don’t fully absorb a dose, you should not take it until the next scheduled dose.
- Infants should be clinically monitored at least once a month. The duration of treatment is at least 6 months.
Acutely threatening supraventricular and ventricular arrhythmias
- Adults : Initially, 1 mg propranolol hydrochloride (corresponds to 1 ml injection solution, i.e. 1 ampoule) is slowly injected intravenously over 1 minute.
- If necessary, the injection can be repeated with the same dose at 2-minute intervals until the onset of action or the maximum dose is reached.
- The maximum dose is 10 mg in conscious adults and 5 mg in anesthetized adults.
- Children and adolescents: Intravenous injection is only intended for the emergency treatment of cardiac arrhythmias. The recommended dosage is 0.025 – 0.05 mg/kg. If necessary, the dose can be repeated every 6-8 hours.
Side effects of Inderal (Propranolol)
The most common side effects of propranolol come from the effect on the autonomic nervous system. Headaches, gastrointestinal problems with diarrhea, vomiting, nausea or constipation, as well as tiredness, dizziness and sweating are examples of these undesirable effects. There is also restlessness, nervousness, confusion or sleep disorders (sometimes with nightmares).
Cardiovascular problems with a drop in blood pressure, cardiac arrhythmia or increased heart failure are other side effects of propranolol, as are skin reactions with a rash, itching or redness and hair loss.
When using propranolol, interactions can occur with the following compounds:
- MAO inhibitors : excessive drop in blood pressure
- Verapamil- or diltiazem – type calcium antagonists : hypotension, bradycardia or other cardiac arrhythmias
- Amiodarone : Enhanced cardiodepressant effects
- Insulins and oral antidiabetics : Increased and prolonged hypoglycaemia
- Other antihypertensive drugs: increased blood pressure reduction
- Alphamethyldopa, guanfacine , cardiac glycosides , clonidine : Greater decrease in heart rate or delay in conduction Excessive increase in blood pressure
- Cimetidine : Enhancement of the propranolol effect
- Rizatriptan : Increased rizatriptan plasma concentrations
Propranolol must not be used with:
- Hypersensitivity to propranolol
- AV block II. and III. Grades and sick sinus syndrome in patients without a pacemaker
- higher grade sinoatrial block
- Untreated heart failure (NYHA III and IV)
- Prinzmetal angina
- pulmonary hypertension
- Bronchial asthma or bronchospasm
- chronic obstructive pulmonary disease
- simultaneous treatment with MAO inhibitors and other drugs that enhance adrenergic impulses
- concomitant treatment with calcium channel antagonists with a negative inotropic effect such as verapamil and diltiazem
- after a long period of fasting
- Metabolic Acidosis
- severe peripheral circulatory disorders
- Patients with a tendency to hypoglycaemia or patients who have been fasting for a long time
- untreated pheochromocytoma.
- Infants under 5 weeks
Propranolol may only be given during pregnancy if there is a strict indication and the risk-benefit ratio has been weighed up. Attention must be paid to possible induction of labor and adverse effects on the fetus (intrauterine growth retardation, bradycardia). Therefore, the therapy should be ended at least 48 – 72 hours before the expected date of delivery. If this is not possible, the newborns must be carefully monitored for the first 48-72 hours after birth.
Because propranolol is a lipophilic beta-blocker, it can get into breast milk. Breastfeeding is therefore not recommended.
Especially at the start of treatment, the ability to react can be altered to such an extent that the ability to actively participate in road traffic and to operate machines is impaired by individually occurring different reactions.
Further information can be found in the respective technical information.
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