Mepivacaine - Dosage, Uses, and Side Effects

Overview

Mepivacaine is an anesthetic agent that is indicated to produce local or regional anesthesia (numbness or loss of sensation) and prevent pain during certain medical procedures in adults and children. The concentration and administration of Mepivacaine depend on the procedure, technique, and area to be anesthetized. Mepivacaine was originally synthesized in Sweden in 1956 and approved by the United States Food and Drug Administration (US FDA) in 1960.

The drug must be used by clinicians who are well-versed in diagnosis and can manage dose-related toxicity or other adverse reactions. A test dose is recommended before administering Mepivacaine (without an antimicrobial preservative) for epidural anesthesia, caudal, and lumbar blocks. The effects of the drug are monitored before the full dose is given. Mepivacaine is not recommended for dental or spinal anesthesia.

How Does Mepivacaine Work?

Mepivacaine is an anesthetic that works by blocking the generation and conduction of nerve impulses that send pain signals to the brain during treatment procedures. It helps to withstand the touch, pain, and change in temperature during the treatment by causing numbness in the area. Mepivacaine (two percent solution) was first introduced in dentistry in 1960.

It is chemically related to Bupivacaine but has a similar potency as Lidocaine. It is less irritant to the tissues and has a milder vasodilating property, which causes a longer duration of anesthetic effect with a vasoconstrictor. Mepivacaine has a rapid onset of action and is used for local and regional anesthesia. It is known to be effective only in large doses for topical application; hence, this route is not recommended.

Indications of Mepivacaine

Mepivacaine produces local or regional anesthesia through local infiltration and central neural techniques, including epidural and caudal blocks and peripheral nerve blocks.

Contraindications of Mepivacaine

Mepivacaine is contraindicated in patients with a history of hypersensitivity to amide-type local anesthetics or other ingredients of the solution. Mepivacaine is also not recommended for pregnant and lactating women.

Available Doses and Dose Forms

Mepivacaine is available as a clear, colorless, sterile injectable solution in the strengths of 1 percent, 1.5 percent, and 2 percent. Each mL (milliliter) contains 10 mg (milligrams), 15 mg, or 20 mg of Mepivacaine hydrochloride respectively.

• 1 percent Mepivacaine is used for local infiltration, peripheral nerve blocks, and caudal and epidural blocks.

• 1.5 percent Mepivacaine solution is used for caudal and epidural blocks.

• 2 percent Mepivacaine solution is used for peripheral nerve blocks, caudal, and epidural blocks.

Warnings and Precautions

• Most of the patients are at risk of developing methemoglobinemia (an abnormal amount of methemoglobin in the blood) after using local anesthetics. It is observed that patients with congenital or idiopathic (spontaneous) methemoglobinemia, glucose-6-phosphate dehydrogenase (G6PD) deficiency (a genetic disorder that occurs due to deficiency of the G6PD enzyme), cardiac or pulmonary disorders, and infants below six months are more susceptible to developing the clinical manifestations of methemoglobinemia. Therefore, close monitoring is required when local anesthetics are administered in such patients.

• Dose-related toxicity (exaggerated drug response that causes harmful effects) can occur with Mepivacaine if proper doses, techniques, or precautions are not taken during administration. The vital signs and consciousness of the patients must be monitored after each dose of the Mepivacaine solution. It must be used with caution in patients with cardiovascular disorders and elderly patients. The lowest possible dose that results in effective anesthesia must be administered in major regional nerve blocks to avoid serious adverse effects.

• Mepivacaine solutions containing antimicrobial preservatives or those supplied in multiple-dose vials must be avoided for epidural and caudal anesthesia as the safety of such products has not been established.

• Post-marketing reports of chondrolysis (cartilage destruction) have been noted in patients receiving intra-articular (into a joint) infusions of local anesthetics such as Mepivacaine during arthroscopic and other surgical procedures. However, sufficient data is not available in this regard; hence, intra-articular infusions must be avoided as it is an unapproved use.

• Unintentional intrathecal (into the spinal canal) or intravascular (into a blood vessel) administration of Mepivacaine can be associated with systemic toxicities (drug responses that affect the entire body or many other organs) such as central nervous system depression, respiratory arrest, paralysis of the legs, bradycardia (slow heart rate), loss of consciousness, or coma. Therefore, intravascular and intrathecal routes must be avoided, and negative aspiration must be ensured before administration of the initial dose and subsequent doses.

• Mepivacaine and other amide-type local anesthetics are metabolized by the liver and excreted by the kidneys. Therefore, dose reduction of Mepivacaine and frequent monitoring must be considered in patients with moderate to severe liver or kidney impairment.

• Dose reduction of Mepivacaine must be considered in patients with cardiovascular disorders, and close monitoring must be done to observe the changes in heart rate, blood pressure, and electrocardiogram (ECG).

• Adverse reactions such as convulsions (uncontrolled shaking), confusion, and respiratory depression can occur with the administration of small doses of Mepivacaine in the head and neck area. Therefore, dosage recommendations must be within the limit, and circulation and respiration must be constantly monitored in patients receiving Mepivacaine blocks. Resuscitative equipment, drugs, and expert healthcare personnel are required to immediately treat adverse reactions.

• Mepivacaine can cause respiratory arrest when administered as a retrobulbar block. Hence, patients must be constantly monitored for any adverse effects during ophthalmic blocks. Immediate treatment measures must be available for the management of any adverse reactions.

Adverse Effects of Mepivacaine

Some of the adverse effects of Mepivacaine include:

• Itching.

• Skin rash.

• Tingling sensation.

• Drowsiness.

• Dizziness.

• Anxiety.

• Confusion.

• Difficulty swallowing.

• Cough.

• Buzzing or ringing in the ears.

• Decreased urination.

• Irregular heartbeat.

• Chest pain and discomfort.

• Difficulty breathing.

• Lack of appetite.

• Sweating.

• Nausea and vomiting.

For Patients

What Is a Local Anesthetic?

A local anesthetic is a medicine used to numb an area of the body to treat certain painful conditions. It can also prevent pain during a procedure or relieve pain after surgery.

Local anesthetics are usually safe, do not cause loss of consciousness, and provide quick recovery. Local anesthetics are commonly used by dentists, general practitioners, anesthetists, and other doctors. Some local anesthetics are also available over-the-counter in pharmacies in the form of gels, sprays, creams, and ointments to manage painful conditions such as sore throats, mouth ulcers, and muscle and joint pain.

What Is Mepivacaine?

Mepivacaine is an anesthetic injection used to cause numbness or loss of sensation or prevent pain during treatment procedures. It belongs to a group of drugs called amide local anesthetics. Mepivacaine works by blocking the sodium channels and inhibiting the nerve impulses that send pain signals to the brain. Mepivacaine does not cause sleep or loss of consciousness. However, if it is given as an epidural (into the back) injection, it may take a little longer for the patient to recover to normal.

How Effective Is Mepivacaine?

Mepivacaine has a rapid onset of action and is almost similar to Lidocaine (a commonly used anesthetic solution for different treatment procedures) in potency, but the duration of action of Mepivacaine is about 90 to 180 minutes, which is slightly longer compared to Lidocaine. However, it may also vary depending on the dose and route of administration. Studies have shown that two percent Mepivacaine is more effective than two percent Lidocaine for treating posterior teeth with irreversible pulpitis (inflammation and completely damaged pulp of the tooth). Mepivacaine also demonstrated the same anesthetic properties as Lidocaine in various clinical trials and is the third most widely used anesthetic agent in dentistry.

How Should the Mepivacaine Be Taken?

Mepivacaine is administered by a trained healthcare professional before the treatment. It is injected into the surgical site through a needle or a catheter into the lower back area for a spinal or epidural block. The dose of Mepivacaine depends on the patient's age, weight, and the procedure, whether it is used for local or regional anesthesia. The patient is monitored for vital signs, level of consciousness, and any adverse effects during and after the procedure.

What Are the Side Effects of Mepivacaine?

Some of the side effects of Mepivacaine include:

• Dizziness.

• Drowsiness.

• Confusion.

• Anxiety.

• Blurred vision.

• Itching.

• Skin rash.

• Shivering.

• Sweating.

• Lack of appetite.

• Irritability.

• Difficulty with urination.

• Irregular heartbeat.

• Chest pain or discomfort.

• Difficulty swallowing.

• Headache.

• Nausea and vomiting.

• Tiredness.

What Must the Patient Inform the Doctor Before Taking Mepivacaine?

• Patients must inform the doctor if they have had any unusual reactions or are allergic to injections or any other medications before taking Mepivacaine.

• Patients must tell the doctor if they are suffering from heart disease, blood disorders, hypertension (increased blood pressure), or any other medical conditions.

• Female patients must inform the doctor if they are pregnant or breastfeeding before taking Mepivacaine.

What Are the Precautionary Measures to Be Followed While Taking Mepivacaine?

• Patients may be assessed for any allergic reactions to Mepivacaine or its components, especially if it contains antimicrobial preservatives, by giving a test dose before administration of the exact dose.

• Mepivacaine can cause methemoglobinemia; therefore, patients or caregivers must inform the doctor of symptoms such as headache, increased heart rate, fatigue, shortness of breath, and pale, grey, or bluish skin discoloration.

• Mepivacaine can cause a temporary loss of sensation, especially in the lower parts of the body, after the administration of epidural or caudal anesthesia.

Storage

Mepivacaine is available in multiple-dose vials and single-dose vials with or without antimicrobial preservatives, respectively. Mepivacaine must be stored at a room temperature of about 20 to 25 degrees Celsius (59 to 86 degrees Fahrenheit). The vials can be sterilized by autoclaving for 15 minutes at 121 degrees Celsius (250 degrees Fahrenheit). It is a clear or colorless solution and must not be administered if it appears cloudy or contains particulate matter. The unused portion of the solution must be discarded.

For Doctors

Pharmacological Aspects of Mepivacaine

Mechanism of Action

Mepivacaine is an amide-based local anesthetic that acts by blocking the generation and conduction of nerve impulses by increasing the threshold for electrical excitation, slowing the propagation, and reducing the rate of action potential. The progression of anesthesia is also related to the conduction velocity, diameter, and myelination of the affected nerve fibers. The loss of nerve function is in the order of pain, temperature, touch, proprioception, and skeletal muscle tone.

Pharmacodynamics

The duration of the anesthetic effect of Mepivacaine depends on the concentration, type of block or technique, and the individual; however, it is adequate for surgery for about 2 to 2.5 hours. After systemic absorption, Mepivacaine produces effects on the central nervous system (CNS) and cardiovascular system (CVS). CNS stimulation is manifested as tremors, shivering, and restlessness and can progress to convulsions, CNS depression, and coma. It also possesses a primary depressant effect on the medulla and higher centers.

Pharmacokinetics

• Absorption: The rate of systemic absorption of Mepivacaine mainly depends on the route of administration, vascularity at the site of administration, total dose and concentration, and the presence or absence of epinephrine. 1: 200000 concentration of Epinephrine usually decreases the rate of absorption and plasma concentration of Mepivacaine.

• Distribution: Approximately 75 percent of Mepivacaine is bound to plasma proteins. Mepivacaine is distributed to some extent to most of the body tissues, such as the lungs, heart, liver, and brain, depending on the route of administration. Mepivacaine also has the potential to cross the placenta by passive diffusion.

• Metabolism: The liver is the primary site of metabolism for Mepivacaine, and more than 50 percent of the administered dose is excreted as metabolites into the bile. Metabolized Mepivacaine is reabsorbed in the intestine and excreted into the urine, with a small percentage in the feces.

• Excretion: The primary route of excretion of Mepivacaine is through the kidneys. Most of the drug and its metabolites are eliminated in around 30 hours. The drug is rapidly metabolized in the body, and only a small percentage is excreted unchanged in the urine.

Drug Interactions

Some of the drugs that interact with Mepivacaine include:

• Bupivacaine.

• Propranolol.

• Timolol.

• Nadolol.

• Pindolol.

• Hyaluronidase.

• St.John’s wort.

• Verapamil.

Clinical Studies

Randomized clinical trials and various case studies have proven that Mepivacaine is a suitable alternative to Lidocaine because its neurological effects are significantly lower compared to Lidocaine. Clinical studies have also reported that Mepivacaine is more effective than Lidocaine in achieving an inferior alveolar nerve block in cases of irreversible pulpitis. However, clinical studies also showed that Mepivacaine can cause adverse effects such as maculopapular rash, skin reactions, urticaria, facial angioedema, and pruritus.

Nonclinical Toxicology

Carcinogenicity studies, mutagenicity studies, and fertility studies have not been conducted with Mepivacaine.

Specific Considerations

• Pregnancy: Mepivacaine and other local anesthetics have the potential to cross the placental barrier and can cause maternal toxicity or fetal harm. Therefore, it is not recommended for pregnant women.

• Lactation: No information is available regarding the presence of Mepivacaine in breast milk, its effects on milk production, or the breastfed infant.

• Pediatric Use: Appropriate doses of Mepivacaine should be carefully determined in children based on age and weight. The dose must not exceed 5 to 6 mg/kg (milligrams per kilogram), especially in those children weighing less than 13.6 kg. For patients under three years of age, or under 13.6 kg, less than two percent concentration of the drug must be considered.

• Geriatric Use: Dose reduction must be considered in geriatric patients due to the probability of decreased hepatic or renal function. The dose must be determined carefully, and the patients must be frequently monitored.

• Hepatic and Renal Impairment: Dose reduction must be considered in patients with moderate to severe hepatic or renal impairment conditions due to the risk of adverse reactions.