Propranolol

Propranolol is a medication of the beta blocker class.<ref name="AHFS2015" /> It is used to treat high blood pressure, some types of irregular heart rate, thyrotoxicosis, capillary hemangiomas, akathisia, performance anxiety, and essential tremors,<ref name="AHFS2015" /><ref name="Dav2006">Template:Cite journal</ref><ref name="Chinnadurai2016">Template:Cite journal</ref><ref>Template:Cite journal</ref> as well to prevent migraine headaches, and to prevent further heart problems in those with angina or previous heart attacks.<ref name="AHFS2015">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> It can be taken orally or by intravenous injection.<ref name="AHFS2015" /> The formulation that is taken orally comes in short-acting and long-acting versions.<ref name="AHFS2015" /> Propranolol appears in the blood after 30 minutes and has a maximum effect between 60 and 90 minutes when taken orally.<ref name="AHFS2015" /><ref>Template:Cite book</ref>

Common side effects include nausea, abdominal pain, and constipation.<ref name=AHFS2015/> It may worsen the symptoms of asthma.<ref name=AHFS2015/> Propranolol may cause harmful effects for the baby if taken during pregnancy;<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> however, its use during breastfeeding is generally considered to be safe.<ref>Template:Cite book</ref> It is a non-selective beta blocker which works by blocking β-adrenergic receptors.<ref name=AHFS2015/>

Propranolol was patented in 1962 and approved for medical use in 1964.<ref>Template:Cite book</ref> It is on the World Health Organization's List of Essential Medicines.<ref name="WHO21st">Template:Cite book</ref> Propranolol is available as a generic medication.<ref name=AHFS2015/> In 2022, it was the 77th most commonly prescribed medication in the United States, with more than 8Template:Nbspmillion prescriptions.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Medical uses

File:Propranolol 80mg.png

An 80 mg capsule of extended-release propranolol

File:Propranolol tablets.png

A mixture of 20 mg and 10 mg extended-release propranolol tablets

File:Propranolol hci sandoz 10mg.jpg

Propranolol blister pack

Propranolol is used for treating various conditions, including:

Cardiovascular

• Hypertension
• Angina pectoris (with the exception of variant angina)
• Myocardial infarction
• Tachycardia (and other sympathetic nervous system symptoms, such as muscle tremor) associated with various conditions, including anxiety, panic, hyperthyroidism, and lithium therapy
• Portal hypertension, to lower portal vein pressure
• Prevention of esophageal variceal bleeding and ascites
• Anxiety
• Hypertrophic cardiomyopathy

While once a first-line treatment for hypertension, the role of beta blockers was downgraded in June 2006 in the United Kingdom to fourth-line, as they do not perform as well as other drugs, particularly in the elderly, and evidence is increasing that the most frequently used beta blockers at usual doses carry an unacceptable risk of provoking type 2 diabetes.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Propranolol is not recommended for the treatment of high blood pressure by the Eighth Joint National Committee (JNC 8) because a higher rate of the primary composite outcome of cardiovascular death, myocardial infarction, or stroke compared to an angiotensin receptor blocker was noted in one study.<ref>Template:Cite journal</ref>

Psychiatric

Propranolol is occasionally used to treat performance anxiety,<ref name=Dav2006/> although evidence to support its use in any anxiety disorders is poor.<ref name="Steenenvan Wijk2015">Template:Cite journal</ref> Its efficacy in managing panic disorder appears similar to benzodiazepines, while carrying lower risks for addiction or abuse.<ref name="Steenenvan Wijk2015"/> Although beta-blockers such as propranolol have been suggested to be beneficial in managing physical symptoms of anxiety, its efficacy in treating generalized anxiety disorder and panic disorder remain unestablished.<ref>Template:Cite journal</ref> Some experimentation has been conducted in other psychiatric areas:<ref name="pmid17200914">Template:Cite journal</ref>

• Post-traumatic stress disorder (PTSD) and specific phobias
• Aggressive behavior of patients with brain injuries<ref name="pmid7903928">Template:Cite journal</ref>
• Treating the excessive drinking of fluids in psychogenic polydipsia<ref name="pmid7737786">Template:Cite journal</ref><ref name="pmid9844835">Template:Cite journal</ref>

PTSD and phobias

Propranolol is being investigated as a potential treatment for PTSD.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>Template:Cite journal</ref><ref>Template:Cite book</ref> Propranolol works to inhibit the actions of norepinephrine (noradrenaline), a neurotransmitter that enhances memory consolidation.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> In one small study, individuals given propranolol immediately after trauma experienced fewer stress-related symptoms and lower rates of PTSD than respective control groups who did not receive the drug.<ref>Template:Cite journal</ref> Due to the fact that memories and their emotional content are reconsolidated in the hours after they are recalled/re-experienced, propranolol can also diminish the emotional impact of already formed memories; for this reason, it is also being studied in the treatment of specific phobias, such as arachnophobia, dental fear, and social phobia.<ref name="Steenenvan Wijk2015" /> It has also been found to be helpful for some individuals with misophonia.<ref>Template:Cite journal</ref>

Ethical and legal questions have been raised surrounding the use of propranolol-based medications for use as a "memory damper", including altering memory-recalled evidence during an investigation, modifying the behavioral response to past (albeit traumatic) experiences, the regulation of these drugs, and others.<ref>Template:Cite journal</ref> However, Hall and Carter have argued that many such objections are "based on wildly exaggerated and unrealistic scenarios that ignore the limited action of propranolol in affecting memory, underplay the debilitating impact that PTSD has on those who suffer from it, and fail to acknowledge the extent to which drugs like alcohol are already used for this purpose".<ref>Template:Cite journal</ref>

Other uses

• Essential tremor. Evidence for use for akathisia however is insufficient<ref>Template:Cite journal</ref>
• Migraine and cluster headache prevention<ref>Template:Cite journal</ref><ref>Template:Cite book</ref> and in primary exertional headache<ref name=AHFS2015/><ref>{{#invoke:citation/CS1|citation

|CitationClass=web }}</ref>

• Hyperhidrosis (excessive sweating)Template:Cn
• Infantile hemangioma<ref>Template:Cite journal</ref>
• GlaucomaTemplate:Cn
• Thyrotoxicosis by deiodinase inhibitionTemplate:Cn

Propranolol may be used to treat severe infantile hemangiomas (IHs). This treatment shows promise as being superior to corticosteroids when treating IHs. Extensive clinical case evidence and a small controlled trial support its efficacy.<ref>Template:Cite journal</ref>

Contraindications

Template:See also Propranolol may be contraindicated in people with:<ref name="Rossi" />

• Reversible airway diseases, particularly asthma or chronic obstructive pulmonary disease (COPD)
• Slow heart rate (bradycardia) (<60 beats/minute)
• Sick sinus syndrome
• Atrioventricular block (second- or third-degree)
• Shock
• Severe low blood pressure

Adverse effects

Propranolol should be used with caution in people with:<ref name="Rossi">Template:Cite book</ref>

• Diabetes mellitus or hyperthyroidism, since signs and symptoms of hypoglycemia may be masked
• Peripheral artery disease and Raynaud syndrome, which may be exacerbated
• Phaeochromocytoma, as hypertension may be aggravated without prior alpha blocker therapy
• Myasthenia gravis, which may be worsened
• Other drugs with bradycardic effects

Pregnancy and lactation

Propranolol, like other beta-blockers, is classified as pregnancy category C in the United States and ADEC category C in Australia. β-blocking agents in general reduce perfusion of the placenta, which may lead to adverse outcomes for the neonate, including lung or heart complications, or premature birth. The newborn may experience additional adverse effects such as low blood sugar and a slower than normal heart rate.<ref name="Martindale">Template:Cite book</ref>

Most β-blocking agents appear in the milk of lactating women. However, propranolol is highly bound to proteins in the bloodstream and is distributed into breast milk at very low levels.<ref name="LactMed">[No authors listed] (2007). "Propranolol". In: Drugs and Lactation Database. U.S. National Library of Medicine Toxicology Data Network. Retrieved 25 February 2013.</ref> These low levels are not expected to pose any risk to the breastfeeding infant, and the American Academy of Pediatrics considers propranolol therapy "generally compatible with breastfeeding."<ref name="Martindale"/><ref name="LactMed"/><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>

Overdose

In overdose, propranolol is associated with seizures.<ref>Template:Cite journal</ref> Cardiac arrest may occur in propranolol overdose due to sudden ventricular arrhythmias, or cardiogenic shock which may ultimately culminate in bradycardic PEA.<ref>Template:Cite journal</ref>

Interactions

Since beta blockers are known to relax the cardiac muscle and constrict the smooth muscle, beta-adrenergic antagonists, including propranolol, have an additive effect with other drugs that decrease blood pressure or decrease cardiac contractility or conductivity. Clinically significant interactions particularly occur with:<ref name="Rossi" />

• Verapamil
• Epinephrine (adrenaline)
• β₂-adrenergic receptor agonists
  • Salbutamol (albuterol), levosalbutamol, formoterol, salmeterol, clenbuterol, others
• Clonidine
• Ergot alkaloids
• Isoprenaline (isoproterenol)
• Nonsteroidal anti-inflammatory drugs (NSAIDs)
• Quinidine
• Cimetidine
• Lidocaine
• Phenobarbital
• Rifampicin
• Fluvoxamine (slows down the metabolism of propranolol significantly, leading to increased blood levels of propranolol)<ref>Template:Cite journal</ref>

Pharmacology

Pharmacodynamics

citation

CitationClass=web }}</ref>
Site	Ki (nM)	Species	Ref
5-HT1A	55–272	Human	<ref name="pmid2078271">Template:Cite journal</ref><ref name="pmid9686407">Template:Cite journal</ref>
5-HT1B	56–85	Rat	<ref name="pmid1968985">Template:Cite journal</ref><ref name="pmid2936965">Template:Cite journal</ref>
5-HT1D	4,070	Pig	<ref name="pmid2797214">Template:Cite journal</ref>
5-HT2A	4,280	Human	<ref name="pmid2723656">Template:Cite journal</ref>
5-HT2B	457–513 (Template:Abbr) 166–316 (Template:Abbr)	Human	<ref name="pmid8743744">Template:Cite journal</ref>
5-HT2C	61,700 (Template:Abbr) 5,010 (Template:Abbr) 736–2,457	Human Human Rodent	<ref name="pmid8743744" /> <ref name="pmid8743744" /> <ref name="pmid4078623">Template:Cite journal</ref><ref name="pmid9686407" />
5-HT3	>10,000	Human	<ref name="pmid2809591">Template:Cite journal</ref>
α1	Template:Abbr	Template:Abbr	Template:Abbr
α2	1,297–2,789	Rat	<ref name="pmid2885406">Template:Cite journal</ref>
β1	0.02–2.69	Human	<ref name="pmid8935801">Template:Cite journal</ref><ref name="pmid7915318">Template:Cite journal</ref>
β2	0.01–0.61	Human	<ref name="pmid8935801" /><ref name="pmid7915318" />
β3	450	Mouse	<ref name="pmid1718744">Template:Cite journal</ref>
D1	>10,000	Human	<ref name="pmid9686407" />
D2	>10,000	Human	<ref name="pmid9686407" />
H1	>10,000	Human	<ref name="pmid6146381">Template:Cite journal</ref>
Template:Abbrlink	3,700	Rat	<ref name="pmid2970277">Template:Cite journal</ref>
Template:Abbrlink	5,000 (Template:Abbrlink)	Rat	<ref name="pmid2872325">Template:Cite journal</ref>
Template:Abbrlink	29,000 (Template:Abbr)	Rat	<ref name="pmid2872325" />
Template:Abbrlink	>10,000	Rat	<ref name="pmid2338642">Template:Cite journal</ref>
Values are Ki (nM), unless otherwise noted. The smaller the value, the more strongly the drug binds to the site.

Propranolol is classified as a competitive non-cardioselective sympatholytic beta blocker that crosses the blood–brain barrier. It is lipid soluble and also has sodium channel-blocking effects. Propranolol is a non-selective β-adrenergic receptor antagonist, or beta blocker;<ref name="Propranolol">Template:Cite book</ref> that is, it blocks the action of epinephrine (adrenaline) and norepinephrine (noradrenaline) at both β₁- and β₂-adrenergic receptors. It has little intrinsic sympathomimetic activity, but has strong membrane stabilizing activity (only at high blood concentrations, e.g. overdose).<ref>Template:Cite book</ref> Propranolol can cross the blood-brain barrier and exert effects in the central nervous system in addition to its peripheral activity.<ref name="Steenenvan Wijk2015"/>

In addition to blockade of adrenergic receptors, propranolol has very weak inhibitory effects on the norepinephrine transporter and/or weakly stimulates norepinephrine release (i.e., the concentration of norepinephrine is increased in the synapse).<ref name="YoungGlennon2008">Template:Cite journal</ref><ref name="pmid2872325"/> Since propranolol blocks β-adrenoceptors, the increase in synaptic norepinephrine only results in α-adrenoceptor activation, with the α₁-adrenoceptor being particularly important for effects observed in animal models.<ref name="YoungGlennon2008" /><ref name="pmid2872325" /> Therefore, it can be looked upon as a weak indirect α₁-adrenoceptor agonist in addition to potent β-adrenoceptor antagonist.<ref name="YoungGlennon2008" /><ref name="pmid2872325" /> In addition to its effects on the adrenergic system, there is evidence that indicates that propranolol may act as a weak antagonist of certain serotonin receptors, namely the 5-HT_1A, 5-HT_1B, and 5-HT_2B receptors.<ref name="pmid9064274">Template:Cite journal</ref><ref name="pmid7938165">Template:Cite journal</ref><ref name="pmid8743744" /> The latter may be involved in the effectiveness of propranolol in the treatment of migraine at high doses.<ref name="pmid8743744" />

Both enantiomers of propranolol have a local anesthetic (topical) effect, which is normally mediated by blockade of voltage-gated sodium channels. Studies have demonstrated propranolol's ability to block cardiac, neuronal, and skeletal voltage-gated sodium channels, accounting for its known membrane stabilizing effect and antiarrhythmic and other central nervous system effects.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>

Mechanism of action

Propranolol is a non-selective beta receptor antagonist.<ref name="Propranolol"/> This means that it does not have preference to β₁ or β₂ receptors. It competes with sympathomimetic neurotransmitters for binding to receptors, which inhibits sympathetic stimulation of the heart. Blockage of neurotransmitter binding to β₁ receptors on cardiac myocytes inhibits activation of adenylate cyclase, which in turn inhibits cAMP synthesis leading to reduced Protein kinase A (PKA) activation. This results in less calcium influx to cardiac myocytes through voltage-gated L-type calcium channels meaning there is a decreased sympathetic effect on cardiac cells, resulting in antihypertensive effects including reduced heart rate and lower arterial blood pressure.<ref name=drugbank /> Blockage of neurotransmitter binding to β₂ receptors on smooth muscle cells will increase contraction, which will increase hypertension.

Pharmacokinetics

Propranolol is rapidly and completely absorbed, with peak plasma levels achieved about 1–3 hours after ingestion. More than 90% of the drug is found bound to plasma protein in the blood.<ref name=drugbank/> Coadministration with food appears to enhance bioavailability.<ref>Template:Cite book</ref> Despite complete absorption, propranolol has a variable bioavailability due to extensive first-pass metabolism. Hepatic impairment therefore increases its bioavailability. Propranolol can be absorbed along the whole intestine with the main absorption site being the colon,<ref>Template:Cite journal</ref> which means people who have lost their colon due to surgery may absorb less propranolol. The main metabolite 4-hydroxypropranolol, with a longer half-life (5.2–7.5 hours) than the parent compound (3–4 hours), is also pharmacologically active. Most of the metabolites are excreted in the urine.<ref name=drugbank>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Propranolol is a highly lipophilic drug achieving high concentrations in the brain. The duration of action of a single oral dose is longer than the half-life and may be up to 12 hours if the single dose is high enough (e.g., 80 mg).<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Effective plasma concentrations are between 10 and 100 mg/L.Template:Citation needed Toxic levels are associated with plasma concentrations above 2000 mg/L.Template:Citation needed

History

{{#invoke:Labelled list hatnote|labelledList|Main article|Main articles|Main page|Main pages}}

Scottish scientist James W. Black developed propranolol in the 1960s.<ref name="Black JW, Crowther AF, Shanks RG, Smith LH, Dornhorst AC 1964 1080–1081">Template:Cite journal</ref> It was the first beta-blocker effectively used in the treatment of coronary artery disease and hypertension.<ref name=":0">Template:Cite book</ref>

Newer, more cardio-selective beta blockers (such as bisoprolol, nebivolol, carvedilol, or metoprolol) are used preferentially in the treatment of hypertension.<ref name=":0" />

Society and culture

In a 1987 study by the International Conference of Symphony and Opera Musicians, it was reported that 27% of interviewed members said they used beta blockers such as propranolol for musical performances.<ref name= Fishbein>Template:Cite journal</ref> For about 10–16% of performers, their degree of stage fright is considered pathological.<ref name= Fishbein/><ref>Template:Cite journal</ref> Propranolol is used by musicians, actors, and public speakers for its ability to treat anxiety symptoms activated by the sympathetic nervous system.<ref>Template:Cite journal</ref> It has also been used as a performance-enhancing drug in sports where high accuracy is required, including archery, shooting, golf,<ref name="ogrady">Template:Cite news</ref> and snooker.<ref name="ogrady"/> In the 2008 Summer Olympics, 50-metre pistol silver medalist and 10-metre air pistol bronze medalist Kim Jong-su tested positive for propranolol and was stripped of his medals.<ref name="Guardian NK Doping">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Brand names

Propranolol was first marketed under the brand name Inderal, manufactured by ICI Pharmaceuticals (now AstraZeneca), in 1965. "Inderal" is a quasi-anagram of "Alderlin", the trade name of pronethalol (which propranolol replaced); both names are an homage to Alderley Park, the ICI headquarters where the drugs were first developed.<ref name=Quirke>Template:Cite journal</ref>

Propranolol is also marketed under brand names Avlocardyl, Deralin, Dociton, Inderalici, InnoPran XL, Indoblok,<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Sumial, Anaprilin, and Bedranol SR (Sandoz). In India, it is marketed under brand names such as Ciplar and Ciplar LA by Cipla. Hemangeol, a 4.28 mg/mL solution of propranolol, is indicated for the treatment of proliferating infantile hemangioma.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Further reading

• Template:Cite journal

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