Browsing Pathways

Aminocaproic acid, brand name Amicar, is a derivate of lysine and is an antifibrinolytic drug. Antifibrinolytics drugs are commonly used during major surgery to prevent significant blood loss. These drugs reversibly blocks the binding sites on plasminogen. This blockade inhibits plasminogen binding to fibrin and the conversion of plasminogen to plasmin. These prevents fibrin degradation and maintains the stability of fibrin clots.

Triamterene is a diuretic that belongs to the potassium-sparing class of drugs which are commonly used to manage hypertension and edema. It acts by blocking epithelial sodium channels in the late distal convoluted tubule of the nephron. Specifically, triamterene inhibits amiloride-sensitive sodium channels which are responsible for the reabsorption of sodium in the late distal convoluted tubule in the nephron. This primarily contributes to an increase in sodium excretion and consequentially, fluid excretion which decreases blood volume and blood pressure. Potassium secretion is indirectly affected by the inhibition of sodium reabsorption due to the elimination of the electrochemical gradient that drives potassium loss. This leads to an increase in serum potassium concentration -- a common action for potassium-sparing drugs -- and has the potential to induce hyperkalemia which can potentially lead to severe heart arrhythmias.

Oxprenolol (also known as Trasacor or Trasicor) is a beta blocker (non-selective) that are used for treat high blood pressure or chest pain. Oxprenolol 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. Oxprenolol can also bind beta-2 adrenergic receptors in juxtaglomerular apparatus and bronchiole smooth muscle. In juxtaglomerular apparatus, oxprenolol 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 oxprenolol to beta-2 adrenergic receptors can also prevent vasoconstriction.

Opiate receptors are coupled with G-protein receptors and function as both positive and negative regulators of synaptic transmission via G-proteins that activate effector proteins. Binding of the opiate stimulates the exchange of GTP for GDP on the G-protein complex. As the effector system is adenylate cyclase and cAMP located at the inner surface of the plasma membrane, opioids decrease intracellular cAMP by inhibiting adenylate cyclase. Subsequently, the release of nociceptive neurotransmitters such as substance P, GABA, dopamine, acetylcholine and noradrenaline is inhibited. Opioids also inhibit the release of vasopressin, somatostatin, insulin and glucagon. Codeine's analgesic activity is, most likely, due to its conversion to morphine. Opioids close N-type voltage-operated calcium channels (OP2-receptor agonist) and open calcium-dependent inwardly rectifying potassium channels (OP3 and OP1 receptor agonist). This results in hyperpolarization and reduced neuronal excitability.

Nicotine is a stimulant drug that acts as an agonist at nicotinic acetylcholine receptors. These are ionotropic receptors composed of five homomeric or heteromeric subunits. In the brain, nicotine binds to nicotinic acetylcholine receptors on dopaminergic neurons in the cortico-limbic pathways. This causes the channel to open and allow conductance of multiple cations including sodium, calcium, and potassium. This leads to depolarization, which activates voltage-gated calcium channels and allows more calcium to enter the axon terminal. Calcium stimulates vesicle trafficking towards the plasma membrane and the release of dopamine into the synapse. Dopamine binding to its receptors is responsible the euphoric and addictive properties of nicotine. Nicotine also binds to nicotinic acetylcholine receptors on the chromaffin cells in the adrenal medulla. Binding opens the ion channel allowing influx of sodium, causing depolarization of the cell, which activates voltage-gated calcium channels. Calcium triggers the release of epinephrine from intracellular vesicles into the bloodstream, which causes vasoconstriction, increased blood pressure, increased heart rate, and increased blood sugar.

Pentazocine (also known as Talwin) is a type of medication that can relieve moderate to severe pain. Pentazocine can bind to mu-type opioid receptor and kappa-type opioid receptor on neuron of central nerves system (CNS). Binding of pentazocine on mu-type opioid receptor and kappa-type opioid receptor can lead to decreased level of neuronal excitability and hyperpolarization. After binding to the receptor, pentazocine will slowly dissociate.

Enalapril (trade name: Vasotec) belongs to the class of drugs known as angiotensin-converting enzyme (ACE) inhibitors and is used primarily to lower high blood pressure (hypertension). This drug can also be used in the treatment of congestive heart failure and type II diabetes. Enalapril is a prodrug which, following oral administration, undergoes biotransformation in vivo into its active form enalaprilat via cleavage of its ester group by the liver. Angiotensin-converting enzyme (ACE) is a component of the body's renin–angiotensin–aldosterone system (RAAS) and cleaves inactive angiotensin I into the active vasoconstrictor angiotensin II. ACE (or kininase II) also degrades the potent vasodilator bradykinin. Consequently, ACE inhibitors decrease angiotensin II concentrations and increase bradykinin concentrations resulting in blood vessel dilation and thereby lowering blood pressure.

Irinotecan is a medication commonly sold as Camptosar, used to stop the growth of cancer cells, and to stop the spread of cancer cells in the human body. Specifically cancers of the rectum and of the colon. Commonly used in combination with chemotherapy. Irinotecan works through its active metabolite, SN-38, which inhibits the action of topoisomerase I. This enzyme is responsible for creating single-strand breaks in DNA during replication. These single-strands are reversible. SN-38 and Irinotecan binding to topoisomerase I-DNA complex results in the prevention of religation the DNA strand mentioned above, which creates double-strand DNA breakage. This breakage leads to cell death. Irinotecan is taken orally, but can also be injected.

Benazepril, brand name Lotensin, belongs to the class of drugs known as angiotensin-converting enzyme (ACE) inhibitors and is used primarily to lower high blood pressure (hypertension). This drug can also be used in the treatment of congestive heart failure and type II diabetes. Benazepril is a prodrug which, following oral administration, undergoes biotransformation in vivo into its active form benazeprilat via cleavage of its ester group by the liver. Angiotensin-converting enzyme (ACE) is a component of the body's renin–angiotensin–aldosterone system (RAAS) and cleaves inactive angiotensin I into the active vasoconstrictor angiotensin II. ACE (or kininase II) also degrades the potent vasodilator bradykinin. Consequently, ACE inhibitors decrease angiotensin II concentrations and increase bradykinin concentrations resulting in blood vessel dilation and thereby lowering blood pressure.

Naproxen (also named Aleve and Naprosyn) is a nonsteroidal anti-inflammatory drug (NSAID). It can be used to relieve pain (analgesic) and reduce fever (antipyretic). Naproxen is also a type of ophthalmic anti-inflammatory medicines. Naproxen can block prostaglandin synthesis by the action of inhibition of prostaglandin G/H synthase 1 and 2. Prostaglandin G/H synthase 1 and 2 catalyze the arachidonic acid to prostaglandin G2, and also catalyze prostaglandin G2 to prostaglandin H2 in the metabolism pathway. Since prostaglandin is the messenger molecules in the process of inflammation; hence, inhibition of prostaglandin synthesis can reduce the pain and inflammation.