Amiodarone, trade name Cordarone and Nexterone, is an antianginal and a class III antiarrhythmic drug prescribed to treat irregular heart rhythms. The drug inhibits Na,K-activated myocardial adenosine triphosphatase, calcium and potassium channels and beta adrenergic receptors causing an increase in ventricular and atrial muscle action duration. This inhibition causes prevents repolarization of the cells causing heart rate to decrease and vascular resistance to decrease. Amiodarone exerts its antiarrhythmic effect by prolonging the duration of myocardial cell-action potentials. Amiodarone is unique to other class III antiarrhythmic drugs due to its effect on beta adrenergic receptors, calcium channels and sodium channels.
Levobunolol (also known as Betagan) is an ophthalmic beta blocker (non-selective) that can produce cardiovascular effects and systemic pulmonary effects. Levobunolol bind to beta1-adrenergic and beta2-adrenergic receptors in heart and vascular smooth muscle to block the binding of other adrenergic neurotransmitters such as norepinephrine, which lead to decreased blood pressure, heart rate and cardiac output.
Metipranolol (also known as Betanol or Disorat) is an beta blocker (non-selective) that can used as an antihypertensive, antiarrhythmic and antiglaucoma agent. Metipranolol binds to beta1-adrenergic and beta2-adrenergic receptors in heart and vascular smooth muscle. Metipranolol demonstrates low intrinsic sympathomimetic activity, and weak local anesthetic (membrane-stabilizing) and myocardial depressant activity. Metipranolol can also reduce the producion of aqueous humor.
Bevantolol hydrocholride, also known as bevantolol, is a cardioselective beta blocker prescribed to treat angina pectoris and hypertension. Bevantolol is an antagonist of beta-1 adrenoreceptors to block the G protein signalling cascade and inhibit epinephrine induced sympathetic activation such as, increased heart rate. It does not have intrinsic sympathomimetic activity therefore does not stimulate beta-adrenergic receptors. This results in a decrease in preload and blood pressure.
Practolol (also known as Eraldin or Dalzic) is a beta blocker (non-selective) that are used for treat high blood pressure or chest pain. Practolol bind to beta1-adrenergic receptors in heart and vascular smooth muscle to block the binding of other adrenergic neurotransmitters such as norepinephrine, which lead to decreased blood pressure, heart rate and cardiac output. Practolol can also bind beta-2 adrenergic receptors in juxtaglomerular apparatus and bronchiole smooth muscle. In juxtaglomerular apparatus, practolol can prevent the production of aldosterone and angiotensin II by inhibiting renin production, which lead to prevention of water retention and vasoconstriction. In bronchiole smooth muscle, binding of practolol to beta-2 adrenergic receptors can also prevent vasoconstriction.
Bupranolol is a nonselective beta-blocker with structural similarity to propanolol. Both drugs do not have intrinsic sympathomimetic activity. It competes with catecholamines for binding beta-1 adrenergic receptors in the heart to inhibit sympathetic activation. This inhibition causes decreased heart rate, cardiac output, blood pressure
Tramadol is an analgesic drug consisting of two enantiomer forms (+)-Tramadol and (-)-Tramadol. Both contribute to pain relief by inhibiting pain transmission in the spinal cord via different mechanisms. (+)-Tramadol is a selective agonist of the mu receptor (OP3) inhibiting serotonin reuptake, while (-)-Tramadol inhibits norepinephrine reuptake in the central nervous system. Although tramadol is structurally related to codeine and morphine, it’s affinity for the mu receptor compared to other opioids is significantly less. Therefore tramadol is used when treatment with strong opioids is not necessary since it’s pharmacodynamic and pharmacokinetic properties suggest the low likelihood of patients becoming dependent.
Propoxyphene is an analgesic in the opioid category. It primarily acts on the G protein coupled receptors, OP3. Propoxyphene binding to OP3 causes GTP exchange for GDP and inhibit adenylate cyclase causing decreased intracellular cAMP. This leads to the inhibition of nociceptive neurotransmitters such as: substance P, GABA, dopamine, acetylcholine and noradrenaline. Opioids inhibit vasopressin, somatostatin, insulin and glucagon release. Propoxyphene also causes the closure of voltage-gated calcium channels and opens potassium channels causing the hyperpolarization of the membrane and decreasing neuronal excitability. This further reduces the feeling of pain.
Levorphanol (also known as Levo-Dromoran) is an opioid medication that can bind to mu-type opioid receptor to activate associated G-protein in the sensory neurons of central nervous system (CNS), which will reduce the level of intracellular cAMP by inhibiting adenylate cyclase. The binding of levorphanol will eventually lead to reduced pain because of decreased nerve conduction and release of neurotransmitter. Therefore, levorphanol can reduce nerve conduction and decrease neurotransmitter release; so that perception of pain signals can be blocked.
Anileridine (also known as Leritine) is analgesic that can bind to mu-type opioid receptor to activate associated G-protein in the sensory neurons of central nervous system (CNS), which will reduce the level of intracellular cAMP by inhibiting adenylate cyclase. The binding of anileridine will eventually lead to reduced pain because of decreased nerve conduction and release of neurotransmitter. Hyperpolarization of neuron is caused by inactivation of calcium channels and activation of potassium channels via facilitated by G-protein.