Digoxin, a cardiac glycoside similar to digitoxin, is used to treat congestive heart failure and supraventricular arrhythmias due to reentry mechanisms, and to control ventricular rate in the treatment of chronic atrial fibrillation. Digoxin inhibits the Na-K-ATPase membrane pump, resulting in an increase in intracellular sodium. The sodium calcium exchanger (NCX) in turn tries to extrude the sodium and in so doing, pumps in more calcium. Increased intracellular concentrations of calcium may promote activation of contractile proteins (e.g., actin, myosin). Digoxin also acts on the electrical activity of the heart, increasing the slope of phase 4 depolarization, shortening the action potential duration, and decreasing the maximal diastolic potential.

Primidone is an anticonvulsant of the barbiturate class. It was introduced in 1954 under the brand name Mysoline by Wyeth in the United States. Mysoline, used alone or concomitantly with other anticonvulsants, is indicated in the control of grand mal, psychomotor, and focal epileptic seizures. It may control grand mal seizures refractory to other anticonvulsant therapy. Mysoline raises electro- or chemoshock seizure thresholds or alters seizure patterns in experimental animals. The mechanism(s) of primidone’s antiepileptic action is not known. Primidone per se has anticonvulsant activity, as do its two metabolites, phenobarbital and phenylethylmalonamide (PEMA). In addition to its anticonvulsant activity, PEMA potentiates the anticonvulsant activity of phenobarbital in experimental animals. Primidone itself doesn’t act on GABA-A receptors. It is active metabolite - phenobarbital primary acts via modulation of GABA -A receptors. The most frequently occurring early side effects are ataxia and vertigo. These tend to disappear with continued therapy, or with reduction of initial dosage. Occasionally, the following have been reported: nausea, anorexia, vomiting, fatigue, hyperirritability, emotional disturbances, sexual impotency, diplopia, nystagmus, drowsiness, and morbilliform skin eruptions.Granulocytopenia, agranulocytosis, and red-cell hypoplasia and aplasia, have been reported rarely. These and, occasionally, other persistant or severe side effects may necessitate withdrawal of the drug. Megaloblastic anemia may occur as a rare idiosyncrasy to Mysoline and to other anticonvulsants. The anemia responds to folic acid without necessity of discontinuing medication.

Levothyroxine (T4) is a synthetically prepared levo isomer of thyroxine, the major hormone secreted from the thyroid gland. Thyroxine is released from thyroglobulin by proteolysis and secreted into the blood. Thyroxine is peripherally deiodinated to form triiodothyronine (T3) which exerts a broad spectrum of stimulatory effects on cell metabolism. Thyroid hormone increases the metabolic rate of cells of all tissues in the body. In the fetus and newborn, thyroid hormone is important for the growth and development of all tissues including bones and the brain. In adults, thyroid hormone helps to maintain brain function, food metabolism, and body temperature, among other effects. The symptoms of thyroid deficiency relieved by levothyroxine include slow speech, lack of energy, weight gain, hair loss, dry thick skin and unusual sensitivity to cold. Levothyroxine acts like the endogenous thyroid hormone thyroxine (T4, a tetra-iodinated tyrosine derivative). In the liver and kidney, T4 is converted to T3, the active metabolite. In order to increase solubility, the thyroid hormones attach to thyroid hormone binding proteins, thyroxin-binding globulin, and thyroxin-binding prealbumin (transthyretin). Transport and binding to thyroid hormone receptors in the cytoplasm and nucleus then takes place. Thus by acting as a replacement for natural thyroxine, symptoms of thyroxine deficiency are relieved. Levothyroxine is used for use alone or in combination with antithyroid agents to treat hypothyroidism, goiter, chronic lymphocytic thyroiditis, myxedema coma, and stupor.

Acetaminophen, also known as paracetamol, is commonly used for its analgesic and antipyretic effects. Its therapeutic effects are similar to salicylates, but it lacks anti-inflammatory, antiplatelet, and gastric ulcerative effects. Acetaminophen (USAN) or Paracetamol (INN) is a widely used analgesic and antipyretic drug that is used for the relief of fever, headaches, and other minor aches and pains. It is a major ingredient in numerous cold and flu medications and many prescription analgesics. It is extremely safe in standard doses, but because of its wide availability, deliberate or accidental overdoses are not uncommon. Acetaminophen, unlike other common analgesics such as aspirin and ibuprofen, has no anti-inflammatory properties or effects on platelet function, and it is not a member of the class of drugs known as non-steroidal anti-inflammatory drugs or NSAIDs. At therapeutic doses, acetaminophen does not irritate the lining of the stomach nor affect blood coagulation, kidney function, or the fetal ductus arteriosus (as NSAIDs can). Acetaminophen is thought to act primarily in the CNS, increasing the pain threshold by inhibiting both isoforms of cyclooxygenase, COX-1, COX-2, and COX-3 enzymes involved in prostaglandin (PG) synthesis. Unlike NSAIDs, acetaminophen does not inhibit cyclooxygenase in peripheral tissues and, thus, has no peripheral anti-inflammatory affects. Acetaminophen indirectly blocks COX, and that this blockade is ineffective in the presence of peroxides. This might explain why acetaminophen is effective in the central nervous system and in endothelial cells but not in platelets and immune cells, which have high levels of peroxides. Studies also report data suggesting that acetaminophen selectively blocks a variant of the COX enzyme that is different from the known variants COX-1 and COX-2. This enzyme is now referred to as COX-3. Its exact mechanism of action is still poorly understood, but future research may provide further insight into how it works. The antipyretic properties of acetaminophen are likely due to direct effects on the heat-regulating centers of the hypothalamus resulting in peripheral vasodilation, sweating and hence heat dissipation.

Methadone, sold under the brand names Dolophine among others, is an synthetic opioid that is used as the hydrochloride to treat pain and as maintenance therapy or to help with detoxification in people with opioid dependence. Methadone hydrochloride is a mu-agonist; a synthetic opioid analgesic with multiple actions qualitatively similar to those of morphine. Some data also indicate that methadone acts as an antagonist at the NMDA-receptor. The contribution of NMDA receptor antagonism to methadone’s efficacy is unknown. Most common adverse reactions are: lightheadedness, dizziness, sedation, nausea, vomiting, and sweating. Avoid use mixed agonist/antagonist and partial agonist opioid analgesics with DOLOPHINE because they may reduce analgesic effect of DOLOPHINE or precipitate withdrawal symptoms.

Ascorbic acid (vitamin C) is a water-soluble vitamin. It occurs as a white or slightly yellow crystal or powder with a slight acidic taste. Ascorbic acid is an electron donor, and this property accounts for all its known functions. As an electron donor, ascorbic acid is a potent water-soluble antioxidant in humans. Ascorbic acid acts as an antioxidant under physiologic conditions exhibiting a cross over role as a pro-oxidant in pathological conditions. Oxidized ascorbic acid (dehydroascorbic acid (DHA) directly inhibits IkappaBalpha kinase beta (IKKbeta) and IKKalpha enzymatic activity in vitro, whereas ascorbic acid did not have this effect. These findings define a function for vitamin C in signal transduction other than as an antioxidant and mechanistically illuminate how vitamin C down-modulates NF-kappaB signaling. Vitamin C is recommended for the prevention and treatment of scurvy. Its parenteral administration is desirable for patients with an acute deficiency or for those whose absorption of orally ingested ascorbic acid (vitamin c) is uncertain. Symptoms of mild deficiency may include faulty bone and tooth development, gingivitis, bleeding gums, and loosened teeth. Febrile states, chronic illness, and infection (pneumonia, whooping cough, tuberculosis, diphtheria, sinusitis, rheumatic fever, etc.) increase the need for ascorbic acid (vitamin c). Hemovascular disorders, burns, delayed fracture and wound healing are indications for an increase in the daily intake.

Folic Acid is a B complex vitamin containing a pteridine moiety linked by a methylene bridge to para-aminobenzoic acid, which is joined by a peptide linkage to glutamic acid. Conjugates of Folic Acid are present in a wide variety of foods, particularly liver, kidneys, yeast and leafy green vegetables. Commercially available Folic Acid is prepared synthetically. Folic Acid occurs as a yellow or yellowish-orange crystalline powder and is very slightly soluble in water and insoluble in alcohol. Aqueous solutions of Folic Acid are heat sensitive and rapidly decompose in the presence of light and/or riboflavin; solutions should be stored in a cool place protected from light. Folic Acid is effective in the treatment of megaloblastic anemias due to a deficiency of Folic Acid (as may be seen in tropical or nontropical sprue) and in anemia of nutritional origin, pregnancy, infancy, or childhood. Folic Acid is relatively nontoxic in man. Rare instances of allergic responses to Folic Acid preparations have been reported and have included erythema, skin rash, itching, general malaise, and respiratory difficulty due to bronchospasm. Endocyte is developing an intravenous (IV) formulation of folic acid, called Neocepri®, which is intended for the diagnosis of positive folate receptor-positive status in patients with ovarian cancer when administered prior to the radioactive medicine, technetium Tc99m Etarfolatide. The benefits of Neocepri® are its ability to reduce the background activity observed on single photon emission computed tomography (SPECT) imaging in most normal, nontarget tissues (e.g. intestines, liver, kidney, spleen), thereby improving the image quality of the scans. The product had been granted orphan drug designation in the EU. Endocyte had filed a conditional marketing authorization application (CMA) with the European Medicines Agency (EMA) for Neocepri®.

Cyanocobalamin (commonly known as Vitamin B12) is the most chemically complex of all the vitamins. Cyanocobalamin's structure is based on a corrin ring, which, although similar to the porphyrin ring found in heme, chlorophyll, and cytochrome, has two of the pyrrole rings directly bonded. The central metal ion is Co (cobalt). Cyanocobalamin is naturally found in foods including meat (especially liver and shellfish), eggs, and milk products.Vitamin B12 is essential to growth, cell reproduction, hematopoiesis, and nucleoprotein and myelin synthesis. Cells characterized by rapid division (e.g., epithelial cells, bone marrow, myeloid cells) appear to have the greatest requirement for vitamin B12. Vitamin B12 can be converted to coenzyme B12 in tissues, and as such is essential for conversion of methylmalonate to succinate and synthesis of methionine from homocysteine, a reaction which also requires folate. In the absence of coenzyme B12, tetrahydrofolate cannot be regenerated from its inactive storage form, 5- methyltetrahydrofolate, and a functional folate deficiency occurs. Vitamin B12 also may be involved in maintaining sulfhydryl (SH) groups in the reduced form required by many SH-activated enzyme systems. Through these reactions, vitamin B12 is associated with fat and carbohydrate metabolism and protein synthesis. Vitamin B12 deficiency results in megaloblastic anemia, GI lesions, and neurologic damage that begins with an inability to produce myelin and is followed by gradual degeneration of the axon and nerve head. Cyanocobalamin is the most stable and widely used form of vitamin B12, and has hematopoietic activity apparently identical to that of the antianemia factor in purified liver extract. Parenteral (intramuscular) administration of vitamin B12 completely reverses the megaloblastic anemia and GI symptoms of vitamin B12 deficiency.

Estradiol benzoate is the synthetic benzoate ester of estradiol, a steroid sex hormone vital to the maintenance of fertility and secondary sexual characteristics in females. As the primary, most potent estrogen hormone produced by the ovaries, estradiol binds to and activates specific nuclear receptors. This agent exhibits mild anabolic and metabolic properties, and increases blood coagulability. Although estradiol benzoate is not approved by the FDA for use in humans in the United States, it is approved for veterinary use as a subdermal implant both alone (CELERIN®) and in combination with the anabolic steroid trenbolone acetate (SYNOVEX® Plus).

Phenytoin is an anti-epileptic drug. Phenytoin has been used with much clinical success against all types of epileptiform seizures, except petit mal epilepsy. Phenytoin is a available for oral administration (tablets, capsules, suspension). CEREBYX® (fosphenytoin sodium injection) is a prodrug intended for parenteral administration; its active metabolite is phenytoin. CEREBYX should be used only when oral phenytoin administration is not possible. Although several potential targets for phenytoin action have been identified within the CNS (Na-K-ATPase, the GABAA receptor complex, ionotropic glutamate receptors, calcium channels and sigma binding sites) to date, though, the best evidence hinges on the inhibition of voltage-sensitive Na channels in the plasma membrane of neurons undergoing seizure activity.