Risedronic acid is a pyridinyl bisphosphonate that inhibits osteoclast-mediated bone resorption and modulates bone metabolism. The action of risedronate on bone tissue is based partly on its affinity for hydroxyapatite, which is part of the mineral matrix of bone. Risedronate also targets farnesyl pyrophosphate (FPP) synthase. It is FDA approved for the treatment of postmenopausal osteoporosis, osteoporosis in men, glucocorticoid-induced osteoporosis and Paget’s disease. Calcium, antacids, or oral medications containing divalent cations interfere with the absorption of Risedronic acid. Common adverse reactions include rash, abdominal pain, constipation, diarrhea, indigestion, nausea, backache, urinary tract infectious disease and influenza-like illness.

Tazarotene a novel acetylenic retinoid is known to be effective in the topical treatment of psoriasis and acne. Tazarotene is rapidly and completely metabolized to its active metabolite tazarotenic acid. The exact mechanism of action of tazarotenic acid in the treatment of psoriasis and acne is not clearly defined. However, it is thought that the selective interaction of tazarotenic acid with the retinoic acid receptor (RAR) family (RARα, RARβ, and RARγ) and the subsequent induction of both positive and negative gene regulatory effects may be involved.

Sodium phenylbutyrate is a salt of an aromatic fatty acid. The compound is used to treat urea cycle disorders, because its metabolites offer an alternative pathway to the urea cycle to allow excretion of excess nitrogen. Sodium phenylbutyrate is also a histone deacetylase inhibitor and chemical chaperone, leading respectively to research into its use as an anti-cancer agent and in protein misfolding diseases such as cystic fibrosis. It is used as adjunctive therapy for the management of chronic urea cycle disorders due to deficiencies in carbamylphosphate (CPS), ornithine transcarbamylase (OTC), or argininosuccinic acid synthetase. It is indicated in all neonatal- onset efficiency presenting within the first 28 days of life. Also indicated in patients with late-onset, presenting after the first month of life with a history of hyperammonemic encephalopathy. Sodium phenylbutyrate is a pro-drug and is rapidly metabolized to phenylacetate. Phenylacetate is a metabolically active compound that conjugates with glutamine via acetylation to form phenylacetylglutamine. The kidneys then excrete Phenylacetylglutamine. PBA (phenylbutyric acid) is absorbed from the intestine and converted by way of β-oxidation to the active moiety, phenylacetic acid (PAA). PAA is conjugated with glutamine in the liver and kidney by way of N-acyl coenzyme A-l-glutamine N-acyltransferase to form phenylacetylglutamine (PAGN). Like urea, PAGN incorporates two waste nitrogens and is excreted in the urine. On a molar basis, it is comparable to urea (each containing two moles of nitrogen). Therefore, phenylacetylglutamine provides an alternate vehicle for waste nitrogen excretion.

Latanoprostene Bunod (LBN) is a topical ophthalmic therapeutic for the reduction of intraocular pressure (IOP) in patients with open-angle glaucoma or ocular hypertension. There is no cure for glaucoma and therapeutic management is predominantly focused on minimizing disease progression and clinical sequelae via the reduction and maintenance of appropriate target IOPs. Latanoprostene Bunod is thought to lower intraocular pressure via a dual mechanism of action since the medication is metabolized into two relevant moieties upon administration: latanoprost acid, and butanediol mononitrate. As a prostaglandin F2-alpha analog, the latanoprost acid moiety operates as a selective PGF2-alpha (FP) receptor agonist. Since FP receptors occur in the ciliary muscle, ciliary epithelium, and sclera the latanoprost acid moiety primarily acts in the uveoscleral pathway where it increases the expression of matrix metalloproteinases (MMPs) like MMP-1, -3, and -9 which promote the degradation of collagen types I, III, and IV in the longitudinal bundles of the ciliary muscle and surrounding sclera. The resultant extracellular matrix remodeling of the ciliary muscle consequently produces reduced outflow resistance via increased permeability and increased aqueous humor outflow through the uveoscleral route. Conversely, the butanediol mononitrate undergoes further metabolism to NO and an inactive 1,4-butanediol moiety. As a gas that can freely diffuse across plasma membranes, it is proposed that the relaxing effect of NO to induce reductions in the cell volume and contractility of vascular smooth muscle-like cells is dependent upon activation of the sGC/cGMP/PKG cascade pathway. NO released from butanediol mononitrate consequently enters the cells of the TM and an inner wall of SC, causing decreases in myosin light chain-2 phosphorylation, increased phosphorylation of large-conductance calcium-activated potassium (BKCa) channels, and a subsequent efflux of potassium ions through such BKCa channels. All of these changes serve to decrease the cell contractility and volume, as well as to rearrange the actin cytoskeleton of the TM and SC cells. These biomechanical changes ultimately allow for enhanced conventional outflow of aqueous humor.

Aminolevulinic Acid is the first compound in the porphyrin synthesis pathway. The metabolism of aminolevulinic acid (ALA) is the first step in the biochemical pathway resulting in heme synthesis. Aminolevulinic acid is not a photosensitizer, but rather a metabolic precursor of protoporphyrin IX (PpIX), which is a photosensitizer. The synthesis of ALA is normally tightly controlled by feedback inhibition of the enzyme, ALA synthetase, presumably by intracellular heme levels. ALA, when provided to the cell, bypasses this control point and results in the accumulation of PpIX, which is converted into heme by ferrochelatase through the addition of iron to the PpIX nucleus. Marketed under the brand name LEVULAN KERASTICK for Topical Solution plus blue light illumination using the BLU-U Blue Light Photodynamic Therapy Illuminator, it is indicated for the treatment of minimally to moderately thick actinic keratoses (Grade 1 or 2, see table 2 for definition) of the face or scalp. Aminolevulinic acid is also being studied in the treatment of other conditions and types of cancer. An orally-administered in vivo diagnostic agent, Aminolevulinic acid, is used in photodynamic diagnosis (PDD) whose aim is to help doctors visualize the tumor tissue during surgical resection of malignant glioma, it is already sold in over 20 European countries including Germany and the U.K. According to the presumed mechanism of action, photosensitization following application of aminolevulinic acid (ALA) topical solution occurs through the metabolic conversion of ALA to protoporphyrin IX (PpIX), which accumulates in the skin to which aminolevulinic acid has been applied. When exposed to light of appropriate wavelength and energy, the accumulated PpIX produces a photodynamic reaction, a cytotoxic process dependent upon the simultaneous presence of light and oxygen. The absorption of light results in an excited state of the porphyrin molecule, and subsequent spin transfer from PpIX to molecular oxygen generates singlet oxygen, which can further react to form superoxide and hydroxyl radicals. Photosensitization of actinic (solar) keratosis lesions using aminolevulinic acid, plus illumination with the BLU-UTM Blue Light Photodynamic Therapy Illuminator (BLU-U), is the basis for aminolevulinic acid photodynamic therapy (PDT).

Alendronic acid is a bisphosphonate drug used for osteoporosis, osteogenesis imperfecta, and several other bone diseases. It is marketed alone as well as in combination with vitamin D. Alendronate inhibits osteoclast-mediated bone-resorption. Like all bisphosphonates, it is chemically related to inorganic pyrophosphate, the endogenous regulator of bone turnover. But while pyrophosphate inhibits both osteoclastic bone resorption and the mineralization of the bone newly formed by osteoblasts, alendronate specifically inhibits bone resorption without any effect on mineralization at pharmacologically achievable doses. Its inhibition of bone-resorption is dose-dependent and approximately 1,000 times stronger than the equimolar effect of the first bisphosphonate drug, etidronate. Under therapy, normal bone tissue develops, and alendronate is deposited in the bone-matrix in a pharmacologically inactive form. For optimal action, enough calcium and vitamin D are needed in the body in order to promote normal bone development. Hypocalcemia should, therefore, be corrected before starting therapy. Treatment of post-menopausal women and people with osteogenesis imperfecta over the age of 22 with alendronic acid has demonstrated normalization of the rate of bone turnover, significant increase in BMD (bone mineral density) of the spine, hip, wrist and total body, and significant reductions in the risk of vertebral (spine) fractures, wrist fractures, hip fractures, and all non-vertebral fractures. In the Fracture Intervention Trial, the women with the highest risk of fracture (by virtue of pre-existing vertebral fractures) were treated with Fosamax 5 mg/day for two years followed by 10 mg/day for the third year. This resulted in approximately 50% reductions in fractures of the spine, hip, and wrist compared with the control group taking placebos. Both groups also took calcium and vitamin D.

Azelaic acid, a naturally occurring saturated dicarboxylic acid found in wheat, rye, and barley, possesses antimicrobial activity, affects keratin production, and reduces inflammation. One of the brand name for azelaic acid is FINACEA,Gel, 15% is indicated for topical treatment of the inflammatory papules and pustules of mild to moderate rosacea. Although some reduction of erythema, which was present in patients with papules, and pustules of rosacea occurred in clinical studies, efficacy for treatment of erythema in rosacea in the absence of papules and pustules has not been evaluated. Rosacea is a common skin condition thought to be primarily an inflammatory disorder. Neutrophils, in particular, have been implicated in the inflammation associated with rosacea and mediate many of their effects through the release of reactive oxygen species. Many effective agents for rosacea, including topical azelaic acid have anti-inflammatory properties. Azelaic acid per se has multiple modes of action in rosacea, but an anti-inflammatory effect achieved by reducing reactive oxygen species appears to be the main pharmacological action. A possible mechanism of action for azelaic acid in the human epidermis includes its possibility to inhibit tyrosinase and of membrane-associated thioredoxin reductase enzymes, this enzyme is shown to regulate tyrosinase through a feedback mechanism involving electron transfer to intracellular thioredoxin, followed by a specific interaction between reduced thioredoxin and tyrosinase.

Mycophenolic acid (MPA) possesses antibacterial, antifungal, antiviral, immunosuppressive and anticancer properties. Mycophenolic acid (MPA) is a fungal metabolite that was initially discovered by Bartolomeo Gosio in 1893 as an antibiotic against anthrax bacillus, Bacillus anthracis. It is an uncompetitive and reversible inhibitor of inosine monophosphate dehydrogenase (IMPDH), and therefore inhibits the de novo pathway of guanosine nucleotide synthesis without incorporation to DNA. It was approved under the brand name Myfortic for the prophylaxis of organ rejection in adult patients receiving a kidney transplant and is indicated for the prophylaxis of organ rejection in pediatric patients 5 years of age and older who are at least 6 months post kidney transplant. Myfortic is to be used in combination with cyclosporine and corticosteroids.

Pamidronic acid (Pamidronate Disodium) is a bone resorption inhibitor. The principal pharmacologic action of pamidronate disodium is inhibition of bone resorption. Although the mechanism of antiresorptive action is not completely understood, several factors are thought to contribute to this action. Pamidronate disodium adsorbs to calcium phosphate (hydroxyapatite) crystals in bone and may directly block dissolution of this mineral component of bone. In vitro studies also suggest that inhibition of osteoclast activity contributes to inhibition of bone resorption. In animal studies, at doses recommended for the treatment of hypercalcemia, pamidronate disodium inhibits bone resorption apparently without inhibiting bone formation and mineralization. Of relevance to the treatment of hypercalcemia of malignancy is the finding that pamidronate disodium inhibits the accelerated bone resorption that results from osteoclast hyperactivity induced by various tumors in animal studies. Pamidronate disodium, in conjunction with adequate hydration, is indicated for the treatment of moderate or severe hypercalcemia associated with malignancy, with or without bone metastases. Pamidronate disodium is indicated for the treatment of patients with moderate to severe Paget’s disease of bone. Pamidronate disodium is indicated, in conjunction with standard antineoplastic therapy, for the treatment of osteolytic bone metastases of breast cancer and osteolytic lesions of multiple myeloma.

Lovastatin acid is an active metabolite of hypolipidemic drug Lovastatin. Lovastatin acid inhibits HMG-CoA reductase. This enzyme catalyzes the conversion of HMG-CoA to mevalonate, which is an early and rate limiting step in the biosynthesis of cholesterol. Lovastatin has been shown to reduce both normal and elevated low-density lipoprotein cholesterol (LDL-C). Lovastatin in approved for prevention of cardiovascular events and hypercholesterolemia. Off-label use of lovastatin includes treatmetn of diabetic dyslipidemia, familial dysbetalipoproteinemia, familial combined hyperlipidemia, or nephrotic hyperlipidemia. Lovastatin was tested in clinical trials agains radioation injury during therapy of prostate cancer.