18 Questions
Which of the following is a leukotriene receptor antagonist?
Zafirlukast
What is the primary mechanism of action of long-acting beta2-agonists (LABAs) in bronchial smooth muscle?
Stimulate ATP and cAMP, leading to bronchodilation
Which receptor subtype is predominant in the heart?
Beta1-receptors
Which of the following is a long-acting beta2-agonist (LABA)?
Salmeterol
Which drug class is associated with Schedule II classification by the DEA?
Opioid analgesics and stimulants
Which of the following statements about beta2-agonists is true?
They are primarily used as bronchodilators
Which beta blocker is specifically indicated for glaucoma?
Levobunolol
Among the listed agents, which one has intrinsic sympathomimetic action?
Oxprenolol
Which beta blocker has both membrane stabilizing effect and antioxidant effect?
Carvedilol
Which agent is specifically indicated for migraine prophylaxis?
Timolol
Among the listed agents, which one is used for the control of tremor, portal hypertension, and esophageal variceal bleeding?
Propranolol
Which beta blocker has greater aqueous solubility?
Carteolol
Which type of drugs are not absorbed from the gut?
Lipid-insoluble and water-insoluble drugs
What is the primary method through which 90% of drugs are absorbed?
Passive diffusion (non-ionic diffusion)
Which drug has 0% protein binding?
Lisinopril
What type of binding lessens the amount of a drug at the active site?
High protein binding
Which form of drug can enter the brain?
Lipid-soluble and non-ionic drugs
Which route of drug administration has the highest bioavailability?
Parenteral
Study Notes
Antidotes
-
Calcium Gluconate is used as an antidote for:
- Beta-Blockers (Propranolol, Sotalol)
- Calcium Channel Blockers (Verapamil)
- Diltiazem
- Isoniazid
- Hydrofluoric acid
- Anticholinergics
- Cholinergics (& vice-versa)
-
Other antidotes:
- Physostigmine for Anticholinergics
- Atropine for Cholinergics
- Prussian blue for Thallium
- Pyridoxine for Isoniazid
Pharmacokinetics
- 90% of drugs are absorbed through passive diffusion (non-ionic diffusion)
- Lipid insoluble and water insoluble drugs are not absorbed from the gut
- Most drugs are weakly acidic or weakly basic because stronger forms have a high ability to form corresponding ions
- Protein binding:
- 0% protein binding: Lisinopril
- 99% protein binding: Oxyphenbutazone (metabolite of phenylbutazone)
- Moderate protein binding is required for efficient drug action
- Extent of binding: albumin > acid glycoprotein > lipoprotein > globulins
Bioavailability
- Bioavailability of higher to lower: parenteral > oral > rectal > topical
- Decreased bioavailability is due to less Vd (volume of distribution)
Pharmacodynamics
- Short-acting barbiturates are due to rapid rate of distribution from brain
- Only unbound drug (free form) undergoes metabolism
- Unbound drug reaches liver first, then goes to other parts like kidneys
- Only lipid-soluble and non-ionic drugs can enter the brain
Leukotriene Modifiers
- Zafirlukast: leukotriene receptor antagonist
- Zileuton: 5-lipoxygenase inhibitor, alternative therapy to low doses of inhaled steroids/nedocromil/cromolyn
Beta-Agonists
- Long-acting beta2-agonists (LABA):
- Salmeterol (Serevent)
- Salmeterol with fluticasone (Advair)
- Stimulate ATP-cAMP, leading to relaxation of bronchial smooth muscle and inhibition of release of mediators of immediate hypersensitivity
Drug Schedules
- Schedule I: high abuse potential (narcotic and hallucination effects), e.g. heroin, marijuana
- Schedule II: high abuse potential with severe psychic or physical dependence liability, e.g. opium, morphine, codeine
Beta-Blockers
- Comparative information:
- Agents with intrinsic sympathomimetic action (ISA): Acebutolol, Carteolol, Celiprolol, Mepindolol, Oxprenolol, Pindolol
- Agents with greater aqueous solubility (hydrophilic beta blockers): Atenolol, Celiprolol, Nadolol, Sotalol
- Agents with membrane stabilizing effect: Acebutolol, Betaxolol, Pindolol, Propranolol
- Agents with antioxidant effect: Carvedilol, Nebivolol
- Indication differences:
- Agents specifically indicated for cardiac arrhythmia: Esmolol, Sotalol, Landiolol
- Agents specifically indicated for congestive heart failure: Bisoprolol, Carvedilol, Sustained-release metoprolol, Nebivolol
- Agents specifically indicated for glaucoma: Betaxolol, Carteolol, Levobunolol, Metipranolol, Timolol
- Agents specifically indicated for myocardial infarction: Atenolol, Metoprolol, Propranolol
- Agents specifically indicated for migraine prophylaxis: Timolol, Propranolol
- Propranolol is the only agent indicated for control of tremor, portal hypertension, and esophageal variceal bleeding, and used in conjunction with α blocker therapy in phaeochromocytoma.
Test your knowledge on the comparative information, pharmacological differences, and indication differences of various beta blockers including agents with intrinsic sympathomimetic action, greater aqueous solubility, membrane stabilizing effect, and antioxidant effect.
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