Small Molecule Drugs Monitoring

Amikacin is a broad-spectrum semi-synthetic aminoglycoside antibiotic, derived from kanamycin with antimicrobial property. Amikacin irreversibly binds to the bacterial 30S ribosomal subunit, specifically locking 16S rRNA and S12 protein within the 30S subunit. This leads to interference with translational initiation complex and Misreading of mRNA, whereby hampering protein synthesis and resulting in bactericidal effect. Like other aminoglycoside antibiotics, amikacin can cause hearing loss, balance problems and kidney problems. Other side effects include paralysis, which can result in an inability to breathe. If used during pregnancy, it may cause permanent deafness in the baby.

Carbamazepine is an anti-epileptic drug used in the treatment of seizures which may also prove effective in the long-term treatment of manic-depressive illnesses. Carbamazepine is a sodium channel blocker. It preferentially binds to the inactive conformation of the voltage-gated sodium channel, which prevents repetition and sustained excitation of the action potential. Carbamazepine has an effect on the serotonin system, but its relevance to its antiepileptic effect is uncertain. There is evidence that it is a serotonin release agent and may even be a serotonin reuptake inhibitor. The side effects of in conditioned carbamazepine dosage can include breathing difficulties, seizures and drowsiness. Serious side effects may include rash, decreased bone marrow function, suicidal thoughts or confusion.

Digoxin is a cardiovascular drug used to treat heart conditions such as arrhythmias and heart failure. Digoxin toxicity can be associated with a number of health problems such as changes in heart rate and rhythm, gastrointestinal problems and fatigue.

The main mechanism of action of digoxin is the inhibition of sodium-potassium adenosine triphosphatase in the myocardium. This inhibition results in an increase in intracellular sodium levels and a decrease in the activity of the sodium-calcium exchanger, which typically introduces three extracellular sodium ions into the cells and delivers one intracellular calcium ion out of the cells. The reversal of the exchanger results in an increase in the intracellular calcium concentration available to the contractile protein. The increase in intracellular calcium prolongs the 4th and 0th phases of cardiac action potential, resulting in a decrease in heart rate. At the same time, increased Ca²⁺ also leads to an increase in the storage of calcium in the sarcoplasmic reticulum, resulting in a corresponding increase in calcium release during each action potential. This leads to an increase in the contractility of the heart without increasing the energy expenditure of the heart.

Gentamicin is an antibiotic drug used to treat a wide range of bacterial infections. Within the therapeutic range, most individuals will respond well to gentamicin treatment and will not experience any side effects. However, the most common complications associated with gentamicin toxicity are ear and hearing problems as well as kidney damage.

Gentamicin is a bactericidal antibiotic that acts by binding to the 30S subunit of bacterial ribosomes and has a negative impact on protein synthesis. The primary mechanism of action is generally thought to play a role in eliminating the ability of ribosomes to distinguish between correctly transferred RNA and messenger RNA interactions. Typically, if the erroneous tRNA is paired with the mRNA codon at the aminoacyl site of the ribosome, the adenosine is excluded and recycled, indicating that the ribosome rejects the aminoacylated tRNA. However, when gentamicin binds to the helix of 16S rRNA, it will force adenosine to maintain their position when there is a correct or homologous match between aa-tRNA and mRNA. This results in incorrect aa-tRNA entering the polypeptide chain, resulting in ribosomes synthesizing proteins containing the wrong amino acids (approximately one in every 500). Mistranslational proteins misfold and aggregate, eventually leading to bacterial death.

Methotrexate is a chemotherapy drug and immune system inhibitor. It is used to treat cancer, autoimmune diseases, ectopic pregnancy and medical abortion. Common side effects include nausea, feeling tired, fever, increased risk of infection, low white blood cell count, and broken skin in the mouth. Other side effects may include liver disease, lung disease, lymphoma and severe rash. In the clinic, methotrexate is used in the treatment of cancer and rheumatoid arthritis. For cancer, methotrexate competitively inhibits dihydrofolate reductase (DHFR), an enzyme involved in the synthesis of tetrahydrofolate. DHFR catalyzes the conversion of dihydrofolate to active tetrahydrofolate. Studies find folic acid is essential for the biosynthesis of purines and pyrimidine bases, so folate synthesis is blocked and nucleoside synthesis is inhibited. For the treatment of rheumatoid arthritis, inhibition of DHFR is not considered to be the primary mechanism, but appears to involve multiple mechanisms, including inhibition of enzymes involved in purine metabolism, leading to accumulation of adenosine; inhibition of T cell activation and inhibition of intercellular Adhesion molecules express T cells; selectively down-regulate B cells; increase CD95 sensitivity of activated T cells; and inhibition of methyltransferase activity, resulting in inactivation of enzyme activity associated with immune system function.

Mycophenolic Acid Mycophenolic Acid is an immunosuppressant used to prevent drug rejection in organ transplants. Mycophenolic acid is an active metabolite of the prodrug mycophenolate mofetil. Mycophenolic acid inhibits inosine monophosphate dehydrogenase (IMPDH), preventing the formation of guanosine monophosphateand synthesis of lymphocyte DNA that results in inhibition of lymphocyte proliferation, antibody production, cellular adhesion, and migration of T and B lymphocytes. In clinical, mycophenolate mofetil is increasingly used as a steroid-retaining treatment for autoimmune diseases and immune-mediated diseases, including Behçet disease, vulgaris Pemphigus, refractory incomplete systemic lupus erythematosus, immunoglobulin nephropathy, small vessel vasculitis and psoriasis.

N-Acetylprocainamide (NAPA) is the N-acetylated metabolite of procainamide. Acecainide is a potassium channel blocker similar to a class III antiarrhythmic drug. This compound binds to the potassium channel and delays phase 3 repolarization. These electrophysiological changes reduce the sensitivity of the cells to electrical stimulation, which leads to an increase in the duration of the action potential and an increase in the effective refractory period. By increasing the effective refractory period, NAPA is very useful in suppressing tachyarrhythmias caused by reentry ventricular arrhythmias. Clinical studies have found that acecainide can cause cardiotoxicity and affect torsades de pointes of ventricular tachycardia. Acecainide can reduce renal function when accumulated during procainamide treatment. Furthermore, when acetamide is present in toxic concentrations, it can result in hypotension, severe left ventricular inhibition, gastrointestinal disorders, insomnia, dizziness, dizziness, blurred vision, numbness and tingling.

Phenobarbital is used to treat all types of seizures. It is as effective in controlling seizures as phenytoin, but phenobarbital is not well tolerated. Phenobarbital may have clinical advantages over carbamazepine in the treatment of partial seizures. It's very long half-life (53-118 hours) means that it is not necessary to take a daily dose for the patient. Studies have found that phenobarbital increases the flux of chloride ions into neurons through the action of GABA A receptors, which reduces the excitability of postsynaptic neurons. By making depolarization of neurons more difficult and the threshold of action potentials of postsynaptic neurons will increase. Sedation and hypnosis are the main side effects of phenobarbital. In addition, phenobarbital also has an effect on the central nervous system, which can cause side effects such as dizziness, nystagmus and ataxia. In elderly patients, it can cause excitement and confusion, and in children, it can lead to contradictory ADHD.

Phenytoin is an anti-epileptic drug used for the control of generalised seizures by slowing down impulses in the brain; however incorrect doses can prove toxic. The effects of incorrect phenytoin treatment can include insomnia, nausea, confusion and fatigue.

Phenytoin is believed to prevent seizures by causing voltage-dependent voltage-gated sodium channel blockade. This prevents continuous high frequency repeated excitation of the action potential. This is achieved by increasing steady-state deactivation to reduce the magnitude of the sodium-dependent action potential. The sodium channel exists in three main conformations: quiescent, open, and inactive. Phenytoin preferentially binds to the inactive form of the sodium channel. Because the time required for the bound drug to separate from the inactive channel, there is a time-dependent blockage of the channel. Due to the depolarization by membrane and the increase in the fraction of inactive channels by repeated firing, the binding of phenytoin to the inactive state can produce a voltage-dependent, use-dependent and time-dependent sodium-dependent action potential blockade.

Procainamide is an oral antiarrhythmic agent that has been in wide use for more than 60 years. Procainamide induces rapid blockade of the sodium channel of batrachotoxin (BTX) in the heart muscle and acts as an antagonist of long-gated closures. Long term procainamide therapy is known to induce hypersensitivity reactions, autoantibody formation and a lupus-like syndrome but is a rare cause of clinically apparent acute liver injury.

Uinidine is a natural cinchona alkaloid which has potent antiarrhythmic activity and has been used for decades in the treatment of atrial and ventricular arrhythmias. This is a stereoisomer of quinine, originally from the bark of the cinchona tree. The drug causes an increase in the duration of the action potential and an increase in the QT interval. Quinidine has been associated with fever, mild jaundice and clinically apparent liver injury in up to 2% of treated patients. Like all other class I antiarrhythmic drugs, quinidine acts primarily by blocking the rapid inward sodium current. The effect of quinidine on sodium current is called "use-dependent blockade." This means that at higher heart rates, blockade increases, while at lower heart rates, blockade decreases. The blocking of rapid inward sodium current results in a decrease in phase 0 depolarization of the cardiac action potential.

Salicylic acid is a colorless, crystalline organic carboxylic acid. It is a lipophilic monohydroxybenzoic acid, a phenolic acid and a beta hydroxy acid (BHA). This colorless crystalline organic acid is widely used in organic synthesis and as a plant hormone. It is derived from the metabolism of salicin. In addition to as an important active metabolite of aspirin (acetylsalicylic acid), it acts as a precursor to salicylic acid, which is best known as a key component of topical anti-acne products. Salicylic acid is toxic if ingested in large quantities, but in small quantities is used as a food preservative and antiseptic in toothpaste. It is also the key additive in many skin-care products for the treatment of acne, psoriasis, callouses, corns, keratosis Pilaris and warts.

The mechanism of action of salicylic acid mainly includes: salicylic acid can reduce the formation of proinflammatory prostaglandins by regulating the expression of COX2 gene. Furthermore, salicylic acid can competitively inhibit the oxidation of uridine-5-diphosphate glucose (UDPG) with nicotinamide adenosine dinucleotide (NAD). Interestingly, it also competitively inhibits the transfer of glucuronyl groups of uridine-5-phosphate glucuronic acid (UDPGA) to phenolic receptors.

Theophylline is used to stimulate muscles in the cardiovascular, respiratory, and central nervous systems. It is a bronchodilator commonly used to treat asthma and other airway diseases. Studies find that Theophylline inhibits TGF-β-mediated transformation of lung fibroblasts into myofibroblasts in COPD and asthma through the cAMP-PKA pathway and inhibits the encoding of COL1 mRNA. In addition, it has been shown that theophylline can reverse steroid insensitivity in COPD patients and asthmatic patients by a distinct mechanism of isolation. The side effects of incorrect therphylline dosage can include increased heart rate, central nervous system effects and seizures.

Tobramycin is an aminoglycoside antibiotic from Streptomyces faecalis that is used to treat various types of bacterial infections, particularly Gram-negative infections. Among them, it is particularly effective against Pseudomonas species. Similar to other aminoglycosides, tobramycin is ototoxic: it can cause hearing loss or loss of balance. It is worth noting that the ototoxicity it induces is usually irreversible. In addition, like all aminoglycosides, tobramycin is also nephrotoxic, which can damage kidney tissue. This toxic effect can be particularly worrying when multiple doses accumulate during treatment or when the kidneys concentrate urine by increasing tubular reabsorption during sleep.

Valproic acid is a drug mainly used to treat epilepsy and bipolar disorder as well as to prevent migraine. It can be used to prevent seizures. Common side effects include nausea, vomiting, lethargy, and dry mouth. Serious side effects may include liver problems, increased pancreatitis and increased risk of suicide. In addition, it is known that this drug causes severe abnormalities in the baby during pregnancy.

Although the mechanism of action of valproic acid is not fully understood, its anticonvulsant effect has traditionally been attributed to the blockade of voltage-gated sodium channels and the increase in gamma-aminobutyric acid (GABA) brain levels. In animals, sodium valproate inhibits the GABA-reducing enzymes such as GABA transaminase and succinate-semialdehyde dehydrogenase, and inhibits the reuptake of GABA by neuronal cells, thereby increasing brain and cerebellum inhibition of synaptic neurotransmitter the level of GABA.

Vancomycin is a broad spectrum antibiotic that has activity against methicillin-resistant strains of Staphylococcus aureus and is generally reserved for serious drug resistant gram-positive infections. Common side effects include pain and allergic reactions in the injection area. Occasionally, hearing loss, hypotension or myelosuppression may occur. The safety during pregnancy is unclear, but no evidence of injury has been found and may be safe for use during breastfeeding.

Vancomycin acts by inhibiting proper cell wall synthesis in Gram-positive bacteria. Due to the different mechanisms of cell wall production by Gram-negative bacteria and various factors associated with entry into the outer membrane of Gram-negative organisms, vancomycin is inactive against them (except for some non-gonococcal species of Neisseria). The large hydrophilic molecule is capable of forming a hydrogen bond interaction with the terminal D-alanyl-D-alanine moiety of the NAM / NAG-peptide. Under normal circumstances, this is a five-point interaction. The combination of vancomycin and D-Ala-D-Ala prevents the cell wall from synthesizing long polymers of N-acetylmuramic acid (NAM) and N-acetylglucosamine (NAG), forming the backbone of the bacterial cell wall and preventing skeletal polymerization.