Metoprolol

Registered South African indications:

• Hypertension
• Angina pectoris
• Cardiac arrhythmias
• Hyperthyroidism
• Myocardial infarction

 Contraindications

• Known hypersensitivity to the active ingredient or any of its excipients
• Second or third degree atrioventricular block
• Uncontrolled heart failure
• Bradycardia
• Sick-sinus syndrome
• Prinzmetal's angina
• Untreated phaeochromocytoma
• Metabolic acidosis
• Severe peripheral arterial disease
• Myocardial infarction complicated by significant bradycardia, first degree heart block, systolic hypotension (less than 100mmHg) and/or severe heart failure and cardiogenic shock
• History of bronchospasm and asthma
• Hypotension
• Diabetes if associated with frequent episodes of hypoglycaemia
• Chronic obstructive pulmonary disease
• Renal failure
• Hepatic failure
• Therapy resistant hypokalaemia and hyponatraemia, hypercalcaemia, symptomatic hyperuricaemia, anuria
• Concomitant intravenous administration of calcium blockers of the type verapamil or diltiazem or other antiarrhythmics (such as disopyramide) is contraindicated (exception: intensive care unit)

Cautions

• Pregnancy
• Breastfeeding
• Renal impairment
• Hepatic impairment
• Elderly
• Avoid abrupt cessation of therapy 
• Liver cirrhosis
• Psoriasis
• History of severe anaphylaxis to allergens
• Myasthenia gravis 
• Diabetes mellitus
• Galactose intolerance
• Lapp lactase deficiency 
• Glucose-galactose malabsorption 
• May impair ability to drive and operate heavy machinery

Forms avail. in SA and covered in this monograph: tab

Hypertension

• Oral (tab): 100-200mg/day, in 1-2 divided doses

Angina pectoris

• Oral (tab): 50-200mg, 12hrly; Max: 400mg/24hrs

Supraventricular tachycardia - maintenance

• Oral (tab): 50-150mg/day, in 2-3 divided doses; Max: 300mg/24hrs

Hyperthyroidism

• Oral (tab): 25-50mg, 6-8hrly; Max: 400mg/24hrs

Myocardial Infarction - maintenance

• Oral (tab): 100mg, 12hrly. Treatment duration: 3 months; Max: 200mg/24hrs

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Do not cut/crush/chew/dissolve

Not established for use in children

Pregnancy

• Caution
• It is recommended that metoprolol should not be administered during pregnancy unless it is considered that the benefit outweighs the possible risk to the foetus. Should therapy with metoprolol be employed, special attention should be paid to the foetus, neonate for any undesirable effects such as slowing of the heart rate
• Metoprolol has, however, been used in pregnancy associated hypertension under close supervision after 20 weeks gestation. Although the drug crosses the placental barrier and is present in cord blood no evidence of foetal abnormalities has been reported. However, there is an increased risk of cardiac and pulmonary complications in the neonate in the postnatal period. Beta-blockers reduce placental perfusion and may cause foetal death and premature birth. Intrauterine growth retardation has been observed after long-time treatment of pregnant women with mild to moderate hypertension. Beta-blockers have been reported to cause bradycardia in the foetus and the newborn child, there are also reports of hypoglycaemia and hypotension in newborn children
• Animal experiments have shown neither teratogenic potential nor other adverse events on the embryo and/or foetus relevant to the safety assessment of metoprolol
• Treatment with metoprolol should be discontinued 48-72 hours before the calculated birth date. If this is not possible, the newborn child should be monitored for 24-48 hours postpartum for signs and symptoms of beta blockade (e.g. cardiac and pulmonary complications)

Breastfeeding

• Caution; not recommended 
• Limited human data: potential toxicity
• It is recommended that metoprolol should not be administered breastfeeding unless it is considered that the benefit outweighs the possible risk to the infant
• The concentration of metoprolol in breast milk is approximately three times higher than the one in the mother's plasma
• To minimize this exposure even further, one reference suggested waiting 3-4 hours after a dose to breastfeed
• Even though the risk of adverse effects in the breastfeeding baby would appear to be low after administration of therapeutic doses of the metoprolol (except in individuals with poor metabolic capacity) breastfeeding babies should be monitored for signs of beta blockade

Renal Impairment

• Caution; no dose adjustment recommended

Hepatic Impairment

• Mild to moderate (Child-Pugh Classes A and B): No dose adjustment recommended
  Start with a low dose and up-titrate according to the clinical response
• Severe (Child-Pugh Class C): Caution; dose adjustment recommended
  Reduce daily dose to 200mg/ 24 hrs

Elderly

• Caution; dose adjustment recommended

Porphyria Information

• Not porphyrinogenic (NP)

Drugs in Sport 

• Prohibited in-and out-of-competition in the following sports:
  • Archery (WA)
  • Shooting (ISSF, IPC)
• Prohibited in-competition only in the following sports:
  • Automobile (FIA)
  • Billiards (all disciplines) (WCBS)
  • Darts (WDF)
  • Golf (IGF)
  • Skiing / Snowboarding (FIS) in ski jumping, freestyle aerials / halfpipe and snowboard halfpipe / big air
  • Underwater sports (CMAS) in constant-weight apnoea with or without fins, dynamic apnoea with and without fins, free immersion apnoea, Jump Blue apnoea, spearfishing, static apnoea, target shooting and variable weight apnoea

Central Nervous System Disorders

• Depression
• Nightmares
• Personality disorder
• Hallucinations
• Dizziness
• Headache
• Decreased alertness
• Somnolence or insomnia
• Paraesthesia
• Fatigue

Cardiovascular Disorders

• Bradycardia
• Heart failure
• Cardiac arrhythmias
• Palpitation
• Cardiac conduction disorders
• Precordial pain
• Increase in existing intermittent claudication
• Orthostatic hypotension
• Oedema
• Raynaud's phenomenon
• Gangrene in patients with pre-existing severe peripheral circulatory disorders

Respiratory Disorders

• Exertional dyspnoea 
• Bronchospasm
• Rhinitis

Gastrointestinal Disorders

• Nausea and vomiting
• Abdominal pain
• Diarrhoea
• Constipation
• Dry mouth
• Retroperitoneal fibrosis 
• Symptoms of thyrotoxicosis may be masked
• Symptoms of hypoglycaemia may be masked

Hepatobiliary Disorders

• Hepatitis
• Abnormal liver function test

Genitourinary Disorders

• Disturbances of libido and potency
• Peyronie's disease 

Endocrine and Metabolic Disorders

• Increased weight

Musculoskeletal Disorders

• Muscle cramps
• Arthritis

Skin and Subcutaneous Tissue Disorders

• Skin rash 
• Urticaria
• Psoriasiform 
• Dystrophic skin lesions
• Photosensitivity
• Hyperhydrosis
• Alopecia
• Worsening of psoriasis

Immune, Blood and Lymphatic System Disorders

• Thrombocytopenia

Sensory Disorders

• Visual disturbance 
• Dry eyes and/or eye irritation
• Tinnitus
• Hearing disorders 

• Anaesthetic agents
• Antidiabetic agents
• Diuretics
• Prazosin
• Calcium channel blockers
• Verapamil
• Diltiazem
• Other antihypertensive drugs  
• Non-steroidal anti-inflammatory drugs
• Sympathetic ganglion blockers
• Other beta blockers
• Monoamine oxidase inhibitors  
• Tricyclic antidepressants
• Selective serotonin reuptake inhibitors
• Barbiturates
• Phenothiazines 
• Antiarrhythmic drugs
• Disopyramide
• Digitalis glycosides 
• Alcohol
• Adrenaline  
• Noradrenaline 
• Ergotamine 
• Sympathomimetic agents 
• CYP450 inducers
• CYP450 inhibitors
• Lidocaine
• Prostaglandin synthetase inhibiters
• Cocaine
• Oestrogens
• Xanthines
• Aldesleukin
• Alprostadil
• Mefloquine 
• Anxiolytics
• Hypnotics
• Corticosteroids
• Tropisetron

None routine. Specific cases may require

• ECG
• Heart rate

Metoprolol is a cardioselective beta-adrenergic blocking agent. It has a predominently beta-1 receptor blocking effect resulting in a decrease in heart rate, cardiac output and blood pressure.

Tablet 100mg

• Lopresor (Novartis) originator