Difenoxin is a 4-phenylpiperidine which is closely related to the opioid analgesic meperidine. Difenoxin alone is a USA Schedule I controlled drug, as it may be habit forming. However, it is listed as a Schedule IV controlled drug if combined with atropine, which is added to decrease deliberate misuse. Motofen(R) is a brand mixture which combines atropine sulfate and difenoxin hydrochloride. It is approved by the FDA to treat acute and chronic diarrhea. Difenoxin is an active metabolite of the anti-diarrheal drug, diphenoxylate, which is also used in combination with atropine in the brand mixture Lomotil(R). It works mostly in the periphery and activates opioid receptors in the intestine rather than the central nervous system (CNS). Difenoxin is also closely related to loperamide, but unlike loperamide it is still capable of crossing the blood brain barrier to produce weak sedative and analgesic effects. However, the antidiarrheal potency of difenoxin is much greater than its CNS effects, which makes it an attractive alternative to other opioids. Motofen(R) is a combination of atropine, an anticholinergic drug, and difenoxin, an antidiarrheal drug. It has been used in many countries for many years as a second line opioid-agonist antidiarrheal, which exists an intermediate between loperamide and paragoric. Diarrhea which is a result of cyclic or diarrhea predominant Inflammatory Bowel Syndrome may not be treated effectively with difenoxin, diphenoxylate, or loperamide. As such, diarrhea and cramping which does not respond to non-centrally acting derivatives or belladonna derivatives such as atropine are often treated with conservative doses of codeine. In patients with acute ulcerative colitis, as induction of toxic megacolon is possible, and thus use of Motofen(R) is cautioned. Motofen(R) has been assigned pregnancy category C by the FDA, and is to be used only when the potential benefits outweigh the potential risk to the fetus. The safety of use during lactation is unknown and thus not recommended. Each five-sided dye free MOTOFEN® tablet contains: 1 mg of difenoxin (equivalent to 1.09 mg of difenoxin hydrochloride) and 0.025 mg of atropine sulfate (equivalent to 0.01 mg of atropine). Difenoxin acts as an antidiarrheal by activating peripheral opioid receptors in the small intestine and thereby inhibiting peristalsis. However, research has suggested that non-opioid receptor pathways exist. This would explain the potent antidiarrheal effects of difenoxin despite only limited opioid action.

Butorphanol is a synthetic opioid agonist-antagonist analgesic with a pharmacological and therapeutic profile that has been well established since its launch as a parenteral formulation in 1978. The introduction of a transnasal formulation of butorphanol represents a new and noninvasive presentation of an analgesic for moderate to severe pain. This route of administration bypasses the gastrointestinal tract, and this is an advantage for a drug such as butorphanol that undergoes significant first-pass metabolism after oral administration. The onset of action and systemic bioavailability of butorphanol following transnasal delivery are similar to those after parenteral administration. Butorphanol blocks pain impulses at specific sites in the brain and spinal cord. Butorphanol has agonistic activity at the κ-receptor and antagonistic activity at the μ-receptor. It also exhibits partial agonistic activity at the σ-receptor.

Cyclobenzaprine is a centrally-acting muscle relaxant which boosts levels of norepinephrine and binds to serotonin receptors in the brain to reduce spasm. Cytochromes P-450 3A4, 1A2, and, to a lesser extent, 2D6, mediate N-demethylation, one of the oxidative pathways for cyclobenzaprine. Cyclobenzaprine relieves skeletal muscle spasm of local origin without interfering with muscle function. Drowsiness, fatigue and sedation (up to 40%) is the most common side effect of Cyclobenzaprine. It may have life-threatening interactions with monoamine oxidase (MAO) inhibitors. Postmarketing cases of serotonin syndrome have been reported during combined use of cyclobenzaprine and other drugs such as selective serotonin reuptake inhibitors (SSRIs), serotonin norepinephrine reuptake inhibitors (SNRIs), tricyclic antidepressants (TCAs), tramadol, bupropion, meperidine, verapamil, or MAO inhibitors.

Disopyramide is an antiarrhythmic drug indicated for the treatment of documented ventricular arrhythmias, such as sustained ventricular tachycardia that are life-threatening. In man, Disopyramide at therapeutic plasma levels shortens the sinus node recovery time, lengthens the effective refractory period of the atrium, and has a minimal effect on the effective refractory period of the AV node. Little effect has been shown on AV-nodal and His-Purkinje conduction times or QRS duration. However, prolongation of conduction in accessory pathways occurs. Disopyramide is a Type 1A antiarrhythmic drug (ie, similar to procainamide and quinidine). It inhibits the fast sodium channels. In animal studies Disopyramide decreases the rate of diastolic depolarization (phase 4) in cells with augmented automaticity, decreases the upstroke velocity (phase 0) and increases the action potential duration of normal cardiac cells, decreases the disparity in refractoriness between infarcted and adjacent normally perfused myocardium, and has no effect on alpha- or beta-adrenergic receptors. It is used for the treatment of documented ventricular arrhythmias, such as sustained ventricular tachycardia, ventricular pre-excitation and cardiac dysrhythmias. It is a Class Ia antiarrhythmic drug.

Cimetidine is a histamine H2-receptor antagonist. It reduces basal and nocturnal gastric acid secretion and a reduction in gastric volume, acidity, and amount of gastric acid released in response to stimuli including food, caffeine, insulin, betazole, or pentagastrin. It is used to treat gastrointestinal disorders such as gastric or duodenal ulcer, gastroesophageal reflux disease, and pathological hypersecretory conditions. Cimetidine inhibits many of the isoenzymes of the hepatic CYP450 enzyme system. Other actions of Cimetidine include an increase in gastric bacterial flora such as nitrate-reducing organisms. Cimetidine binds to an H2-receptor located on the basolateral membrane of the gastric parietal cell, blocking histamine effects. This competitive inhibition results in reduced gastric acid secretion and a reduction in gastric volume and acidity.

Tamoxifen (brand name Nolvadex), is selective estrogen receptor modulators (SERM) with tissue-specific activities for the treatment and prevention of estrogen receptor positive breast cancer. Tamoxifen itself is a prodrug, having relatively little affinity for its target protein, the estrogen receptor (ER). It is metabolized in the liver by the cytochrome P450 isoform CYP2D6 and CYP3A4 into active metabolites such as 4-hydroxytamoxifen (4-OHT) (afimoxifene) and N-desmethyl-4-hydroxytamoxifen (endoxifen) which have 30–100 times more affinity with the ER than tamoxifen itself. These active metabolites compete with estrogen in the body for binding to the ER. In breast tissue, 4-OHT acts as an ER antagonist so that transcription of estrogen-responsive genes is inhibited. Tamoxifen has 7% and 6% of the affinity of estradiol for the ERα and ERβ, respectively, whereas 4-OHT has 178% and 338% of the affinity of estradiol for the ERα and ERβ. The prolonged binding of tamoxifen to the nuclear chromatin of these results in reduced DNA polymerase activity, impaired thymidine utilization, blockade of estradiol uptake, and decreased estrogen response. It is likely that tamoxifen interacts with other coactivators or corepressors in the tissue and binds with different estrogen receptors, ER-alpha or ER-beta, producing both estrogenic and antiestrogenic effects. Tamoxifen is currently used for the treatment of both early and advanced estrogen receptor (ER)-positive (ER+) breast cancer in pre- and post-menopausal women. Additionally, it is the most common hormone treatment for male breast cancer. Patients with variant forms of the gene CYP2D6 (also called simply 2D6) may not receive full benefit from tamoxifen because of too slow metabolism of the tamoxifen prodrug into its active metabolites. Tamoxifen is used as a research tool to trigger tissue-specific gene expression in many conditional expression constructs in genetically modified animals including a version of the Cre-Lox recombination technique. Tamoxifen has been shown to be effective in the treatment of mania in patients with bipolar disorder by blocking protein kinase C (PKC), an enzyme that regulates neuron activity in the brain. Researchers believe PKC is over-active during the mania in bipolar patients.

Thallous chloride (also known as Thallium(I) chloride) is a chemical compound with the formula TlCl. Thallous Chloride Tl 201 Injection is a diagnostic radiopharmaceutical indicated for: Myocardial perfusion imaging with planar scintigraphy or single-photon emission computed tomography (SPECT) for the diagnosis of coronary artery disease by localization of: Non-reversible defects (myocardial infarction) which may have prognostic value regarding survival. Reversible defects (myocardial ischemia) when used in conjunction with exercise or pharmacologic stress. Localization of sites of parathyroid hyperactivity pre- and post-operatively in patients with elevated serum calcium and parathyroid hormone levels.

Diflorasone is a topical corticosteroid used to treat itching and inflammation of the skin. Topical corticosteroids share anti-inflammatory, antipruritic and vasoconstrictive actions. The mechanism of anti-inflammatory activity of the topical corticosteroids is unclear. Various laboratory methods, including vasoconstrictor assays, are used to compare and predict potencies and/or clinical efficacies of the topical corticosteroids. There is some evidence to suggest that a recognizable correlation exists between vasoconstrictor potency and therapeutic efficacy in man. The extent of percutaneous absorption of topical corticosteroids is determined by many factors including the vehicle, the integrity of the epidermal barrier, and the use of occlusive dressings. Topical corticosteroids can be absorbed from normal intact skin. Inflammation and/or other disease processes in the skin increase percutaneous absorption. Occlusive dressings substantially increase the percutaneous absorption of topical corticosteroids. Thus, occlusive dressings may be a valuable therapeutic adjunct for treatment of resistant dermatoses. Once absorbed through the skin, topical corticosteroids are handled through pharmacokinetic pathways similar to systemically administered corticosteroids. Corticosteroids are bound to plasma proteins in varying degrees. They are metabolized primarily in the liver and are then excreted by the kidneys. Some of the topical corticosteroids and their metabolites are also excreted into the bile.

Clemastine is an antihistamine with anticholinergic (drying) and sedative side effects. Clemastine is a selective histamine H1 antagonist and binds to the histamine H1 receptor. This blocks the action of endogenous histamine, which subsequently leads to temporary relief of the negative symptoms brought on by histamine. It is used for the relief of symptoms associated with allergic rhinitis such as sneezing, rhinorrhea, pruritus and acrimation. Also for the management of mild, uncomplicated allergic skin manifestations of urticaria and angioedema. Used as self-medication for temporary relief of symptoms associated with the common cold.

Baclofen (brand names Kemstro, Lioresal, and Gablofen) is a derivative of gamma-aminobutyric acid (GABA). Baclofen is a muscle relaxer and an antispastic agent and is used to treat muscle symptoms caused by multiple sclerosis, including spasm, pain, and stiffness. It is primarily used to treat spasticity and is under investigation for the treatment of alcoholism. Although baclofen is an analog of the putative inhibitory neurotransmitter gamma-aminobutyric acid (GABA), there is no conclusive evidence that actions on GABA systems are involved in the production of its clinical effects. Baclofen is rapidly and extensively absorbed and eliminated. Absorption may be dose-dependent, being reduced with increasing doses. Baclofen is excreted primarily by the kidney in unchanged form and there is relatively large intersubjective variation in absorption and/or elimination. Baclofen is a direct agonist at GABA-B receptors. The precise mechanism of action of baclofen is not fully known. It is capable of inhibiting both monosynaptic and polysynaptic reflexes at the spinal level, possibly by hyperpolarization of afferent terminals, although actions at supraspinal sites may also occur and contribute to its clinical effect.