Prenavo DR Tablet (Delayed Release)

Introduction

Pyridoxine Hydrochloride (Vitamin B6) and Doxylamine Succinate are commonly used together to treat nausea and vomiting during pregnancy, commonly referred to as morning sickness. This combination works by addressing vitamin B6 deficiency while providing anti-nausea effects from doxylamine, an antihistamine.

Uses

The primary use of Pyridoxine Hydrochloride and Doxylamine Succinate is to treat nausea and vomiting associated with pregnancy (morning sickness). This combination is typically prescribed when non-pharmacological treatments are not effective.

Brand Name	Prenavo DR
Type	Tablet (Delayed Release)
Weight	10 mg+10 mg
Generic	Pyridoxine Hydrochloride + Doxylamine Succinate
Manufacturer	Kumudini Pharma Ltd.
Available in	English বাংলা

Mechanism of Action

Pyridoxine (Vitamin B6) plays a key role in metabolism and neurotransmitter synthesis. Its exact mechanism in reducing nausea is unclear but may involve balancing neurotransmitter activity. Doxylamine is an H1 receptor antagonist (antihistamine), which works by inhibiting histamine-mediated pathways that trigger nausea and vomiting.

How Long Does It Take to Work?

The combination usually starts working within 1 to 2 hours after administration. However, maximum therapeutic effect may be observed after several days of regular dosing.

Absorption

Pyridoxine is well absorbed in the gastrointestinal tract, with peak plasma concentrations reached within 1-2 hours. Doxylamine is also rapidly absorbed, with peak effects occurring within 2 to 3 hours after oral administration.

Route of Elimination

Pyridoxine and its metabolites are primarily excreted via the urine. Doxylamine is metabolized in the liver and excreted primarily in the urine as metabolites.

Dosage

Initially, take one tablet orally at bedtime (Day 1). If this dose adequately controls symptoms the next day, continue taking one tablet daily at bedtime only. However, if symptoms persist on Day 2, increase the daily dose to one tablet in the morning and one tablet at bedtime. The maximum recommended dose is two tablets per day, one in the morning and one at bedtime. Take on an empty stomach with a glass of water. Swallow tablets whole. Do not crush, chew, or split this tablets. Take daily and not on an as needed basis.

The usual dosage for treating morning sickness is:

Starting dose: One tablet (10 mg of doxylamine and 10 mg of pyridoxine) at bedtime.
If symptoms persist, an additional tablet in the morning may be prescribed.
Maximum dose: Two tablets at bedtime, one in the morning, and one in the afternoon, not to exceed four tablets per day.

Administration

Tablets should be taken on an empty stomach with water. If nausea and vomiting are severe, patients may need to take the medication multiple times a day as instructed by their healthcare provider.

Side Effects

Common side effects of this combination include:

Drowsiness (due to doxylamine)
Dry mouth
Constipation
Dizziness

These side effects are generally mild and improve with continued use.

Toxicity

Overdose of pyridoxine or doxylamine can result in symptoms such as confusion, drowsiness, convulsions, and respiratory depression. In the event of an overdose, emergency medical attention is required.

Precautions

This combination should be used with caution in patients with:

Asthma
Glaucoma
Peptic ulcers
Urinary retention
Severe liver disease

Interaction

Pyridoxine and Doxylamine may interact with:

CNS depressants, such as alcohol or sedatives, which may increase drowsiness.
Anticholinergic drugs, as the combination may enhance anticholinergic effects like dry mouth and constipation.

Disease Interaction

This combination should be used cautiously in patients with conditions like asthma, glaucoma, and severe liver disease, as doxylamine may exacerbate these conditions.

Drug Interaction

Potential drug interactions include:

Alcohol and CNS depressants: Can enhance the sedative effects of doxylamine.
MAO inhibitors: May prolong or intensify anticholinergic and CNS depressive effects.

Food Interactions

There are no significant food interactions with this combination. However, taking the medication on an empty stomach may help increase its effectiveness.

Pregnancy Use

The combination of Pyridoxine and Doxylamine is commonly used during pregnancy for nausea and vomiting and is considered safe when used under a healthcare provider’s supervision. It is classified as a pregnancy category A drug (safe in pregnancy).

Lactation Use

Doxylamine may pass into breast milk and cause sedation in a breastfeeding infant. Caution is advised, and patients should consult their healthcare provider before using this combination while breastfeeding.

Acute Overdose

Overdose symptoms may include severe drowsiness, confusion, respiratory depression, or convulsions. Immediate medical intervention is required in case of an overdose.

Contraindication

Contraindications include:

Hypersensitivity to Pyridoxine, Doxylamine, or any component of the formulation.
Patients taking monoamine oxidase inhibitors (MAOIs).

Use Direction

The medication should be taken as directed by a healthcare provider. If nausea and vomiting persist or worsen, consult a doctor for dosage adjustments. Patients should not exceed the recommended dose.

Storage Conditions

Store at room temperature, away from moisture and heat. Keep the medication in its original container and out of reach of children.

Volume of Distribution

For doxylamine, the volume of distribution is relatively large, indicating extensive distribution into body tissues. Pyridoxine’s volume of distribution is also wide due to its water-soluble nature.