DermacinRx DPN Pak

Uses

Duloxetine Hydrochloride is used for the-

• Treatment of Major Depressive Disorder (MDD)
• Management of neuropathic pain associated with diabetic peripheral neuropathy.
• Chronic Musculoskeletal Pain
• Urinary stress incontinence.

Lidocaine is a topical anesthetic used for the following purposes-

• To help prevent pain associated with minor surgical procedures in the ear, nose and throat
• To help prevent pain and or discomfort during dental procedures (e.g., prior to an injection)
• During general anesthesia to prevent coughing
• To help prevent pain during the final stages of childbirth, before the cutting or stitching of the perineum (skin between the vagina and anus)

DermacinRx DPN Pak is also used to associated treatment for these conditions: Back Pain Lower Back Chronic, Chemotherapy-induced Peripheral Neuropathy (CIPN), Chronic Musculoskeletal Pain, Diabetic Peripheral Neuropathy (DPN), Fibromyalgia, Generalized Anxiety Disorder (GAD), Major Depressive Disorder (MDD), Osteoarthritis of the Knee, Stress Urinary Incontinence (SUI)Acute Otitis Media, Anal Fissures, Anorectal discomfort, Arrhythmia, Back Pain Lower Back, Bacterial Vaginosis (BV), Burns, Cervical Syndrome, Earache, Hemorrhoids, Infection, Inflammatory Reaction caused by ear infection-not otherwise specified, Insect Bites, Joint Pain, Mixed Vaginal Infections, Multiple Myeloma (MM), Myringitis, Neuritis, Osteolysis caused by Bone Tumors, Osteoporosis, Otitis Externa, Pain caused by ear infection-not otherwise specified, Pain, Inflammatory, Post-Herpetic Neuralgia (PHN), Postherpetic Neuralgia, Primary Hyperparathyroidism, Rheumatic Diseases, Rheumatic Joint Disease, Sciatica, Skin Irritation, Soft Tissue Inflammation, Sore Throat, Sunburn, Susceptible infections, Trichomonas Vaginitis, Ulcers, Leg, Urethral Strictures, Vulvovaginal Candidiasis, Abrasions, Anal discomfort, Arrhythmia of ventricular origin, Cutaneous lesions, Gum pain, Minor burns, Superficial Wounds, Susceptible Bacterial Infections, Ulceration of the mouth, Viral infections of the external ear canal, Post Myocardial Infarction Treatment, Regional Anesthesia, Local anesthesia therapy

How DermacinRx DPN Pak works

Duloxetine is a potent inhibitor of neuronal serotonin and norepinephrine reuptake and a less potent inhibitor of dopamine reuptake. Duloxetine has no significant affinity for dopaminergic, adrenergic, cholinergic, histaminergic, opioid, glutamate, and GABA receptors.

Action on the external urinary sphincter is mediated via duloxetine's CNS effects. Increased serotonin and norepinephrine concentrations in Onuf's nucleus leads to increased activation of 5-HT₂, 5-HT₃, and α₁ adrenergic receptors. 5-HT₂ and α₁ are both G_q coupled and their activation increases the activity of the inositol trisphosphate/phospholipase C (IP₃/PLC) pathway. This pathway leads to release of intracellular calcium stores, increasing intracellular calcium concentrations, and facilitating neuronal excitability. 5-HT₃ functions as a ligand-gated sodium channel which allows sodium to flow into the neuron when activated. Increased flow of sodium into the neuron contributes to depolarization and activation of voltage gated channels involved in action potential generation. The combined action of these three receptors contributes to increased excitability of the pudendal motor nerve in response to glutamate.

Also related to duloxetine's action at the spinal cord is its modulation of pain. Increasing the concentration of serotonin and norepinephrine in the dorsal horn of the spinal cord increases descending inhibition of pain through activation of 5-HT_1A, 5-HT_1B, 5-HT_1D, 5-HT₂, 5-HT₃, α₁-adrenergic, and α₂-adrenergic receptors. 5-HT₂, 5-HT₃, and α₁-adrenergic mediate neuronal activation as described above. The activated neuron in this case is the GABAergic inhibitory interneuron which synapses onto the nociceptive projection neuron to inhibit the transmission of painful stimuli to the brain. The 5-HT₁ and α₂ receptors are G_i/G_o coupled and their activation leads to increased potassium current through inward rectifier channels and decreased adenylyl cyclase/protein kinase A signaling which contributes to neuronal inhibition. These inhibitory receptors are present on the projection neuron itself as well as the dorsal root ganglion which precedes it and serves to directly suppress the transmission of painful stimuli.

The mechanisms involved in duloxetine's benefits in depression and anxiety have not been fully elucidated. Dysfunctional serotonin and norepinephrine signaling are thought to be involved and increases in the availability of these neurotransmitters at the synaptic cleft thought to mediate a therapeutic effect. It is postulated that the involvement of serotonin and norepinephrine in area responsible for emotional modulation such as the limbic system contributes to the effects in mood disorders specifically but this has yet to be confirmed.

Duloxetine's hypertensive effect is related to its intended pharmacological effect. Increased availability of norepinephrine leads to activation of adrenergic receptors on the vascular endothelium. Since the action of α₁ receptors predominates, vasoconstriction results as the G_q coupled receptor mediates calcium release from the sarcoplasmic reticulum to facilitate smooth muscle contraction.

Lidocaine is a local anesthetic of the amide type . It is used to provide local anesthesia by nerve blockade at various sites in the body . It does so by stabilizing the neuronal membrane by inhibiting the ionic fluxes required for the initiation and conduction of impulses, thereby effecting local anesthetic action . In particular, the lidocaine agent acts on sodium ion channels located on the internal surface of nerve cell membranes . At these channels, neutral uncharged lidocaine molecules diffuse through neural sheaths into the axoplasm where they are subsequently ionized by joining with hydrogen ions . The resultant lidocaine cations are then capable of reversibly binding the sodium channels from the inside, keeping them locked in an open state that prevents nerve depolarization . As a result, with sufficient blockage, the membrane of the postsynaptic neuron will ultimately not depolarize and will thus fail to transmit an action potential . This facilitates an anesthetic effect by not merely preventing pain signals from propagating to the brain but by aborting their generation in the first place .

In addition to blocking conduction in nerve axons in the peripheral nervous system, lidocaine has important effects on the central nervous system and cardiovascular system . After absorption, lidocaine may cause stimulation of the CNS followed by depression and in the cardiovascular system, it acts primarily on the myocardium where it may produce decreases in electrical excitability, conduction rate, and force of contraction .

Dosage

DermacinRx DPN Pak dosage

Major Depressive Disorder (MDD): Starting dose- 20-30 mg b.i.d or 60 mg once daily, Target dose- 60 mg once daily, max. dose- 60 mg once daily

Diabetic peripheral neuropathy: Starting dose- 60 mg/day (once daily), Target dose- 60 mg once daily, max. dose- 60 mg once daily

Chronic Musculoskeletal Pain: Starting dose- 30 mg/day, Target dose- 60 mg once daily, max. dose- 60 mg once daily

Urinary stress incontinence: Starting dose- 40 mg /day, Target dose- 80 mg/day (twice daily, max. dose- 80 mg/day (twice daily).

Intramuscular:Emergency treatment of ventricular arrhythmias: 300 mg injected into the deltoid muscle, repeat after 60-90 min if necessary.

Intraspinal:Spinal anaesthesia: As hyperbaric soln of 1.5% or 5% lidocaine in 7.5% glucose soln. Normal vaginal delivery: Up to 50 mg (as 5% soln) or 9-15 mg (as 1.5% soln). Caesarian operation: Up to 75 mg (as 5% soln). Other surgical procedures: 75-100 mg.Intravenous:Pulseless ventricular fibrillation or ventricular tachycardia : 1-1.5 mg/kg repeated as necessary. Max: 3 mg/kg. For ventricular arrhythmias in more stable patients: Usual loading dose: 50-100 mg as an IV inj at 25-50 mg/min, may repeat once or twice up to a max of 200-300 mg in 1 hr, followed by 1-4 mg/min via continuous IV infusion. May need to reduce dose if the infusion is longer than 24 hr.

Intravenous:Intravenous regional anaesthesia: As 0.5% soln w/o epinephrine: 50-300 mg. Max: 4 mg/kg.

Parenteral:Percutaneous infiltration anaesthesia: As 0.5% or 1% soln: 5-300 mg.Sympathetic nerve block: As 1% soln: 50 mg for cervical block or 50-100 mg for lumbar block.Peripheral nerve block:

• As 1.5% soln: For brachial plexus block: 225-300 mg.
• As 2% soln: For dental nerve block: 20-100 mg.
• As 1% soln: For intercostal nerve block: 30 mg;
• For paracervical block: 100 mg on each side, repeated not more frequently than every 90 min;
• For paravertebral block: 30-50 mg;
• For pudendal block: 100 mg on each side.
• As 4% soln: For retrobulbar block: 120-200 mg.

Spray:

• The maximum dose is 200 mg (Approximately 20 spray).
• In dentistry, the normal dose is 1-5 sprays. Two sprays per quarter of the mouth is recommended, with a maximum of 3 sprays per quarter of the mouth over 30 minutes.
• In sinus procedures 3 sprays are used.
• In procedures of the throat and windpipe, up to 20 sprays may be necessary.
• Up to 20 sprays may be necessary in childbirth (cesarian procedure).
• Lower doses are used for children aged 3-12 years. Lidocaine 10% Spray is not recommended for children under 3 years.

Topical: Anaesthesia before e.g. venepuncture (not for infants), apply a thick layer under an occlusive dressing 1-5 hours before procedure; split skin grafting, apply a thick layer under an occlusive dressing 2-5 hours before procedure; genital warts (not for children), apply up to 10 gm 5-10 minutes before removal.

Side Effects

The most commonly observed adverse events in Duloxetine hydrochloride treated patients were nausea, dizziness, dry mouth, constipation, decreased appetite, fatigue, somnolence, increased sweating, hyperhidrosis and asthenia. It may slightly increase blood pressure. No clinically significant differences were observed for QT, PR, and QRS intervals between Duloxetine -treated and placebo-treated patients.

Arrhythmia, bradycardia, arterial spasms, CV collapse, oedema, flushing, hert block, hypotension, sinus node suppression, agitation, anxiety, coma, confusion, drowsiness, hallucinations, euphoria, headache, hyperaesthesia, hypoaesthesia, lightheadedness, lethargy, nervousness, psychosis, seizure, slurred speech, unconsciousness, somnolence, nausea, vomiting, metallic taste, tinnitus, disorientation, dizziness, paraesthesia, resp depression and convulsions. Patch: Bruising, depigmentation, petechiae, irritation. Ophth: Conjunctival hyperaemia, corneal epithelial changes, diplopia,visual changes.

Toxicity

Overdose

Fatalities have been reported with doses of 1000mg involving both mixed drugs as well as duloxetine alone. Signs and symptoms of overdose include: somnolence, coma, serotonin syndrome, seizure, syncope, hypo- or hypertension, tachycardia, and vomiting. No antidote exists and the drug is unlikely to be cleared by hemodialysis. Supportive care is recommended along with activated charcoal and gastric lavage to reduce absorption. If serotonin syndrome occurs specific treatment such as temperature control or cyproheptadine may be initiated.

Carcinogenicity & Mutagenicity

Increased incidence of hepatocellular carcinomas and adenomas were reported in female mice fed 140 mg/kg/day duloxetine for 2 years, equivalent to 6 times the maximum recommended human dose (MRHD). No effect was reported with doses of 50mg/kg/day (2 time MRHD) in females or 100 mg/kg/day in males (4 times MRHD). Similar investigation in rats produced no carcinogenicity at doses of 27 mg/kg/day (2 times MRHD)in females and 36 mg/kg/day in males (4 times MRHD).

No mutagenicity, clastogenicity, induction of sister chromatid exchange, or genotoxicity has been observed in toxicology investigations.

Reproductive Toxicity

Neither male or female rats displayed adverse reproductive effects at doses up to 45 mg/kg/day (4 times MRHD).

Lactation

An estimated 25% of plasma duloxetine appears in breast milk with the estimated daily infant dose being 0.14% of the maternal dose. Breast milk concentrations have been observed to peak 3 hours after administration.

Symptoms of overdose and/or acute systemic toxicity involves central nervous system toxicity that presents with symptoms of increasing severity . Patients may present initially with circumoral paraesthesia, numbness of the tongue, light-headedness, hyperacusis, and tinnitus . Visual disturbance and muscular tremors or muscle twitching are more serious and precede the onset of generalized convulsions . These signs must not be mistaken for neurotic behavior . Unconsciousness and grand mal convulsions may follow, which may last from a few seconds to several minutes . Hypoxia and hypercapnia occur rapidly following convulsions due to increased muscular activity, together with the interference with normal respiration and loss of the airway . In severe cases, apnoea may occur. Acidosis increases the toxic effects of local anesthetics . Effects on the cardiovascular system may be seen in severe cases . Hypotension, bradycardia, arrhythmia and cardiac arrest may occur as a result of high systemic concentrations, with potentially fatal outcome .

Pregnancy Category B has been established for the use of lidocaine in pregnancy, although there are no formal, adequate, and well-controlled studies in pregnant women . General consideration should be given to this fact before administering lidocaine to women of childbearing potential, especially during early pregnancy when maximum organogenesis takes place . Ultimately, although animal studies have revealed no evidence of harm to the fetus, lidocaine should not be administered during early pregnancy unless the benefits are considered to outweigh the risks . Lidocaine readily crosses the placental barrier after epidural or intravenous administration to the mother . The ratio of umbilical to maternal venous concentration is 0.5 to 0.6 . The fetus appears to be capable of metabolizing lidocaine at term . The elimination half-life in the newborn of the drug received in utero is about three hours, compared with 100 minutes in the adult . Elevated lidocaine levels may persist in the newborn for at least 48 hours after delivery . Fetal bradycardia or tachycardia, neonatal bradycardia, hypotonia or respiratory depression may occur .

Local anesthetics rapidly cross the placenta and when used for epidural, paracervical, pudendal or caudal block anesthesia, can cause varying degrees of maternal, fetal and neonatal toxicity . The potential for toxicity depends upon the procedure performed, the type and amount of drug used, and the technique of drug administration . Adverse reactions in the parturient, fetus and neonate involve alterations of the central nervous system, peripheral vascular tone, and cardiac function .

Maternal hypotension has resulted from regional anesthesia . Local anesthetics produce vasodilation by blocking sympathetic nerves . Elevating the patient’s legs and positioning her on her left side will help prevent decreases in blood pressure . The fetal heart rate also should be monitored continuously, and electronic fetal monitoring is highly advisable .

Epidural, spinal, paracervical, or pudendal anesthesia may alter the forces of parturition through changes in uterine contractility or maternal expulsive efforts . In one study, paracervical block anesthesia was associated with a decrease in the mean duration of first stage labor and facilitation of cervical dilation . However, spinal and epidural anesthesia have also been reported to prolong the second stage of labor by removing the parturient’s reflex urge to bear down or by interfering with motor function . The use of obstetrical anesthesia may increase the need for forceps assistance .

The use of some local anesthetic drug products during labor and delivery may be followed by diminished muscle strength and tone for the first day or two of life . The long-term significance of these observations is unknown . Fetal bradycardia may occur in 20 to 30 percent of patients receiving paracervical nerve block anesthesia with the amide-type local anesthetics and may be associated with fetal acidosis . Fetal heart rate should always be monitored during paracervical anesthesia . The physician should weigh the possible advantages against risks when considering a paracervical block in prematurity, toxemia of pregnancy, and fetal distress . Careful adherence to the recommended dosage is of the utmost importance in obstetrical paracervical block . Failure to achieve adequate analgesia with recommended doses should arouse suspicion of intravascular or fetal intracranial injection . Cases compatible with unintended fetal intracranial injection of local anesthetic solution have been reported following intended paracervical or pudendal block or both. Babies so affected present with unexplained neonatal depression at birth, which correlates with high local anesthetic serum levels, and often manifest seizures within six hours . Prompt use of supportive measures combined with forced urinary excretion of the local anesthetic has been used successfully to manage this complication .

It is not known whether this drug is excreted in human milk . Because many drugs are excreted in human milk, caution should be exercised when lidocaine is administered to a nursing woman .

Dosages in children should be reduced, commensurate with age, body weight and physical condition .

The oral LD 50 of lidocaine HCl in non-fasted female rats is 459 (346-773) mg/kg (as the salt) and 214 (159-324) mg/kg (as the salt) in fasted female rats .

Precaution

Duloxetine hydrochloride should ordinarily not be prescribed to patients with substantial alcohol use. Blood pressure should be measured prior to initiating treatment and periodically measured throughout treatment. It should be used cautiously in patients with a history of mania, seizure disorder and controlled narrow-angle glaucoma.

Patient with pseudocholinesterase deficiency, resp depression. Hepatic and renal impairment. Elderly or debilitated patients. Pregnancy and lactation.

Interaction

Monoamine oxidase inhibitors (MAOIs): Due to the risk of serotonin syndrome, Duloxetine should not be used in combination with non selective, irreversible monoamine oxidase inhibitors (MAOIs), or within at least 14 days of discontinuing treatment with an MAOI.

Inhibitors of CYP1A2: Because CYP1A2 is involved in Duloxetine metabolism, concomitant use with potent inhibitors of CYP1A2 is likely to result in higher concentrations of Duloxetine. Therefore, Duloxetine should not be administered in combination with potent inhibitors of CYP1A2 like fluvoxamine.

CNS medicinal products: Caution is advised when Duloxetine is taken in combination with other centrally acting medicinal products or substances, including alcohol and sedative medicinal products (e.g., benzodiazepines, morphinomimetics, antipsychotics, phenobarbital, sedative antihistamines).

May increase serum levels with cimetidine and propranolol. Increased risk of cardiac depression with β-blockers and other antiarrhythmics. Additive cardiac effects with IV phenytoin. Hypokalaemia caused by acetazolamide, loop diuretics and thiazides may antagonise effect of lidocaine. Dose requirements may be increased with long-term use of phenytoin and other enzyme-inducers.

Volume of Distribution

Apparent Vd of 1620-1800 L. Duloxetine crosses the blood-brain barrier and collects in the cerebral cortex at a higher concentration than the plasma.

The volume of distribution determined for lidocaine is 0.7 to 1.5 L/kg .

In particular, lidocaine is distributed throughout the total body water . Its rate of disappearance from the blood can be described by a two or possibly even three-compartment model . There is a rapid disappearance (alpha phase) which is believed to be related to uptake by rapidly equilibrating tissues (tissues with high vascular perfusion, for example) . The slower phase is related to distribution to slowly equilibrating tissues (beta phase) and to its metabolism and excretion (gamma phase) .

Lidocaine's distribution is ultimately throughout all body tissues . In general, the more highly perfused organs will show higher concentrations of the agent . The highest percentage of this drug will be found in skeletal muscle, mainly due to the mass of muscle rather than an affinity .

Elimination Route

Duloxetine is incompletely absorbed with a mean bioavailability of 50% although there is wide variability in the range of 30-80%. The population absorption constant (ka) is 0.168 h^{-1 Administering duloxetine with food 3 hour delay in Tmax along with an 10% decrease in AUC. Similarly, administering the dose at bedtime produces a 4 hour delay and 18% decrease in AUC with a 29% reduction in Cmax. These are attributed to delayed gastric emptying in both cases but are not expected to impact therapy to a clinically significant degree.}

In general, lidocaine is readily absorbed across mucous membranes and damaged skin but poorly through intact skin . The agent is quickly absorbed from the upper airway, tracheobronchial tree, and alveoli into the bloodstream . And although lidocaine is also well absorbed across the gastrointestinal tract the oral bioavailability is only about 35% as a result of a high degree of first-pass metabolism . After injection into tissues, lidocaine is also rapidly absorbed and the absorption rate is affected by both vascularity and the presence of tissue and fat capable of binding lidocaine in the particular tissues .

The concentration of lidocaine in the blood is subsequently affected by a variety of aspects, including its rate of absorption from the site of injection, the rate of tissue distribution, and the rate of metabolism and excretion . Subsequently, the systemic absorption of lidocaine is determined by the site of injection, the dosage given, and its pharmacological profile . The maximum blood concentration occurs following intercostal nerve blockade followed in order of decreasing concentration, the lumbar epidural space, brachial plexus site, and subcutaneous tissue . The total dose injected regardless of the site is the primary determinant of the absorption rate and blood levels achieved . There is a linear relationship between the amount of lidocaine injected and the resultant peak anesthetic blood levels .

Nevertheless, it has been observed that lidocaine hydrochloride is completely absorbed following parenteral administration, its rate of absorption depending also on lipid solubility and the presence or absence of a vasoconstrictor agent . Except for intravascular administration, the highest blood levels are obtained following intercostal nerve block and the lowest after subcutaneous administration .

Additionally, lidocaine crosses the blood-brain and placental barriers, presumably by passive diffusion .

Half Life

Mean of 12 h with a range of 8-17.

The elimination half-life of lidocaine hydrochloride following an intravenous bolus injection is typically 1.5 to 2.0 hours . Because of the rapid rate at which lidocaine hydrochloride is metabolized, any condition that affects liver function may alter lidocaine HCl kinetics . The half-life may be prolonged two-fold or more in patients with liver dysfunction .

Clearance

There is a large degree of interindividual variation reported in the clearance of duloxetine with values ranging from 57-114 L/h. Steady state concentrations have still been shown to be dose proportional with a doubling of dose from 30 to 60 mg and from 60 to 120 mg producing 2.3 and 2.6 times the Css respectively.

The mean systemic clearance observed for intravenously administered lidocaine in a study of 15 adults was approximately 0.64 +/- 0.18 L/min .

Elimination Route

About 70% of duloxetine is excreted in the urine mainly as conjugated metabolites. Another 20% is present in the feces as the parent drug, 4-hydroxy metabolite, and an uncharacterized metabolite. Biliary secretion is thought to play a role due to timeline of fecal excretion exceeding the time expected of normal GI transit.

The excretion of unchanged lidocaine and its metabolites occurs predominantly via the kidney with less than 5% in the unchanged form appearing in the urine . The renal clearance is inversely related to its protein binding affinity and the pH of the urine . This suggests by the latter that excretion of lidocaine occurs by non-ionic diffusion .

Pregnancy & Breastfeeding use

Pregnancy: Pregnancy Category C. There are no adequate and well-controlled studies in pregnant women; therefore, Duloxetine should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Labor and Delivery: The effect of Duloxetine on labor and delivery in humans is unknown. Duloxetine should be used during labor and delivery only if the potential benefit justifies the potential risk to the fetus.

Lactation: It is unknown whether or not Duloxetine and/or it's metabolites are excreted into human milk, but nursing while on Duloxetine is not recommended.

Category B: Either animal-reproduction studies have not demonstrated a foetal risk but there are no controlled studies in pregnant women or animal-reproduction studies have shown an adverse effect (other than a decrease in fertility) that was not confirmed in controlled studies in women in the 1st trimester (and there is no evidence of a risk in later trimesters).

Contraindication

Duloxetine is contraindicated in patients with a known hypersensitivity to this drug or any of the inactive ingredients. Concomitant use in patients taking monoamine oxidase inhibitors (MAOIs) is contraindicated. It should be avoided in patients with uncontrolled narrow-angle glaucoma.

Hypovolaemia, complete heart block, Adam-Stokes syndrome, Wolff-Parkinson-White syndrome. Must not be applied to inflamed or injured skin.

Special Warning

Use in children: Safety and efficacy in pediatric patients have not been established.

Hepatic Impairment Parenteral: Dosage reduction may be needed.

Acute Overdose

There is limited clinical experience with Duloxetine overdose in humans. There is no specific antidote to Duloxetine. In case of acute overdose, treatment should consist of those general measures employed in the management of overdose with any drug. An adequate airway, oxygenation, and ventilation should be assured, and cardiac rhythm and vital signs should be monitored. Induction of emesis is not recommended. Gastric lavage with a large-bore orogastric tube with appropriate airway protection, if needed, may be indicated if performed soon after ingestion or in symptomatic patients. Activated charcoal may be useful in limiting absorption of Duloxetine from the gastrointestinal tract.

Symptoms: Severe hypotension, asystole, bradycardia, apnoea, seizures, coma, cardiac arrest, resp arrest and death.

Management: Maintain oxygenation, stop convulsion and support the circulation.

Storage Condition

Store in a cool and dry place, protected from light and moisture.

Store below 25°C.

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