Drugs List

Therapeutic Indications

Uses

Severe vomiting during pregnancy

Nausea and vomiting during pregnancy in women who do not respond to conservative management.

Contraindications

Children under 18 years

Precautions and Warnings

Asthma
Bladder outflow obstruction
Breastfeeding
Narrow angle glaucoma
Pyloroduodenal obstruction
Raised intra-ocular pressure
Stenosing peptic ulcer

Advise ability to drive/operate machinery may be affected by side effects
Reassess need for continued treatment at regular intervals
May affect results of some laboratory tests
To discontinue, reduce dose gradually
Advise that effects are potentiated by CNS depressants (including alcohol)

Whilst high doses of pyridoxine pose little risk to the foetus, the manufacturer advises that additional intake of vitamin B6 from supplements and/or diet is assessed.

Pregnancy and Lactation

Pregnancy

Doxylamine and pyridoxine is intended for use in pregnant women.

A large amount of data on pregnant women indicates no malformative nor foetal neonatal toxicity with doxylamine and pyridoxine.

The use of all medication in pregnancy should be avoided whenever possible; particularly in the first trimester. Non-drug treatments should also be considered. When essential, a medication with the best safety record over time should be chosen, employing the lowest effective dose for the shortest possible time. Polypharmacy should be avoided. Teratogens taken in the pre-embryonic period, often quoted as lasting until 14 to 17 days post-conception, are believed to have an all-or-nothing effect. Where drugs have a short half-life, and when the date of conception is certain, this may allow women to be reassured where drug exposure has occurred within this time frame. Further advice may be available from the UK National Teratology Information Service (NTIS) and through ToxBase, available via password on the internet ( www.toxbase.org ) or if this is unavailable at the backup site ( www.toxbasebackup.org ).

Lactation

Use doxylamine with pyridoxine with caution in breastfeeding.

The effects of doxylamine and pyridoxine as a combined drug during breastfeeding are unclear.

Doxylamine
The molecular weight of doxylamine is low enough that passage into breast milk can be expected. Excitement, irritability and sedation have been reported in nursing infants presumably exposed to doxylamine through breast milk, particularly following high doses or prolonged use. Infants with apnoea or other respiratory syndromes may be particularly vulnerable to sedative effects.

Pyridoxine
Pyridoxine is excreted into breast milk. There have been no reports of adverse events in infants presumably exposed to pyridoxine through breast milk.

A risk to breastfed infants cannot be excluded.

The manufacturer advises either discontinuing breastfeeding or discontinuing or abstaining from doxylamine and pyridoxine therapy.

Neonates, infants born prematurely, those with low birth weight, those with an unstable gastrointestinal function or who have serious illnesses may require special consideration. For any infant, if a drug is prescribed to the nursing mother, it should be at the lowest practical dose and for the shortest time. When drug administration is unavoidable and breastfeeding is to continue, minimisation of exposure of the infant to the drug may sometimes be achieved by timing the maternal doses to just after a feeding episode. Infants exposed to drugs via breast milk should be monitored for unusual signs or symptoms. Interactions between the drug received by the infant from the mother's milk and medication prescribed for the infant should also be considered, for example, when the drug given to the infant may prevent metabolism of the drug received via breast milk.
Specialist advice is available from the UK Drugs in Lactation Advisory Service at https://www.midlandsmedicines.nhs.uk/content.asp?section=6&subsection=17&pageIdx=1

Side Effects

Abdominal distension
Abdominal pain
Acute labyrinthitis
Agranulocytosis
Anxiety
Blurred vision
Chest discomfort
Chest tightness
Chills
Constipation
Diarrhoea
Diplopia
Disorientation
Dizziness
Dry mouth
Dry throat
Dyskinesia
Dyspnoea
Dysuria
Early menses
Faintness
Fatigue
Haemolytic anaemia
Headache
Hyperhidrosis
Hypersensitivity reactions
Increased appetite
Insomnia
Irritability
Leukopenia
Maculopapular rash
Malaise
Migraine
Nasal dryness
Nasal stuffiness
Nervousness
Nightmares
Palpitations
Pancytopenia
Paraesthesia
Pruritus
Psychomotor hyperactivity
Rash
Somnolence
Sweating
Tachycardia
Thickening of bronchial secretions
Thrombocytopenia
Tinnitus
Toxic psychosis
Tremor
Urinary retention
Vertigo
Visual disturbances
Weight gain
Wheezing

Presentation

Oral formulations of doxylamine succinate with pyridoxine hydrochloride.

Drugs List

Therapeutic Indications

Uses

Severe vomiting during pregnancy

Nausea and vomiting during pregnancy in women who do not respond to conservative management.

Dosage

To be taken as a daily prescription and not on an as needed basis.

Adults

Contraindications

Children under 18 years

Precautions and Warnings

Asthma
Bladder outflow obstruction
Breastfeeding
Narrow angle glaucoma
Pyloroduodenal obstruction
Raised intra-ocular pressure
Stenosing peptic ulcer

Advise ability to drive/operate machinery may be affected by side effects
Reassess need for continued treatment at regular intervals
May affect results of some laboratory tests
To discontinue, reduce dose gradually
Advise that effects are potentiated by CNS depressants (including alcohol)

Whilst high doses of pyridoxine pose little risk to the foetus, the manufacturer advises that additional intake of vitamin B6 from supplements and/or diet is assessed.

Pregnancy and Lactation

Pregnancy

Doxylamine and pyridoxine is intended for use in pregnant women.

A large amount of data on pregnant women indicates no malformative nor foetal neonatal toxicity with doxylamine and pyridoxine.

The use of all medication in pregnancy should be avoided whenever possible; particularly in the first trimester. Non-drug treatments should also be considered. When essential, a medication with the best safety record over time should be chosen, employing the lowest effective dose for the shortest possible time. Polypharmacy should be avoided. Teratogens taken in the pre-embryonic period, often quoted as lasting until 14 to 17 days post-conception, are believed to have an all-or-nothing effect. Where drugs have a short half-life, and when the date of conception is certain, this may allow women to be reassured where drug exposure has occurred within this time frame. Further advice may be available from the UK National Teratology Information Service (NTIS) and through ToxBase, available via password on the internet ( www.toxbase.org ) or if this is unavailable at the backup site ( www.toxbasebackup.org ).

Lactation

Use doxylamine with pyridoxine with caution in breastfeeding.

The effects of doxylamine and pyridoxine as a combined drug during breastfeeding are unclear.

Doxylamine
The molecular weight of doxylamine is low enough that passage into breast milk can be expected. Excitement, irritability and sedation have been reported in nursing infants presumably exposed to doxylamine through breast milk, particularly following high doses or prolonged use. Infants with apnoea or other respiratory syndromes may be particularly vulnerable to sedative effects.

Pyridoxine
Pyridoxine is excreted into breast milk. There have been no reports of adverse events in infants presumably exposed to pyridoxine through breast milk.

A risk to breastfed infants cannot be excluded.

The manufacturer advises either discontinuing breastfeeding or discontinuing or abstaining from doxylamine and pyridoxine therapy.

Neonates, infants born prematurely, those with low birth weight, those with an unstable gastrointestinal function or who have serious illnesses may require special consideration. For any infant, if a drug is prescribed to the nursing mother, it should be at the lowest practical dose and for the shortest time. When drug administration is unavoidable and breastfeeding is to continue, minimisation of exposure of the infant to the drug may sometimes be achieved by timing the maternal doses to just after a feeding episode. Infants exposed to drugs via breast milk should be monitored for unusual signs or symptoms. Interactions between the drug received by the infant from the mother's milk and medication prescribed for the infant should also be considered, for example, when the drug given to the infant may prevent metabolism of the drug received via breast milk.
Specialist advice is available from the UK Drugs in Lactation Advisory Service at https://www.midlandsmedicines.nhs.uk/content.asp?section=6&subsection=17&pageIdx=1

Side Effects

Abdominal distension
Abdominal pain
Acute labyrinthitis
Agranulocytosis
Anxiety
Blurred vision
Chest discomfort
Chest tightness
Chills
Constipation
Diarrhoea
Diplopia
Disorientation
Dizziness
Dry mouth
Dry throat
Dyskinesia
Dyspnoea
Dysuria
Early menses
Faintness
Fatigue
Haemolytic anaemia
Headache
Hyperhidrosis
Hypersensitivity reactions
Increased appetite
Insomnia
Irritability
Leukopenia
Maculopapular rash
Malaise
Migraine
Nasal dryness
Nasal stuffiness
Nervousness
Nightmares
Palpitations
Pancytopenia
Paraesthesia
Pruritus
Psychomotor hyperactivity
Rash
Somnolence
Sweating
Tachycardia
Thickening of bronchial secretions
Thrombocytopenia
Tinnitus
Toxic psychosis
Tremor
Urinary retention
Vertigo
Visual disturbances
Weight gain
Wheezing

Effects on Laboratory Tests

Laboratory tests may be affected by the use of doxylamine with pyridoxine, including false positive urine screens for methadone, opiates and phencyclidine phosphate (PCP). In the event of a positive immunoassay result, a confirmatory test such as Gas Chromatography Mass Spectrometry should be used to identify the substance.

Overdosage

It is strongly recommended that the UK National Poisons Information Service be consulted on cases of suspected or actual overdose where there is doubt over the degree of risk or about appropriate management.

The following number will direct the caller to the relevant local centre (0844) 892 0111

Information may be obtained if you have access to ToxBase the primary clinical toxicology database of the National Poisons Information Service. This is available via password on the internet ( www.toxbase.org ) or if this is unavailable at the backup site ( www.toxbasebackup.org ).

Further Information

Last Full Review Date: August 2018

Reference Sources

Drugs During Pregnancy and Lactation: Treatment Options and Risk Assessment, 3rd edition (2015) ed. Schaefer, C., Peters, P. and Miller, R. Elsevier, London.

Drugs in Pregnancy and Lactation: A Reference Guide to Fetal and Neonatal Risk, 10th edition (2015) ed. Briggs, G., Freeman, R. Wolters Kluwer Health, Philadelphia.

Summary of Product Characteristics: Xonvea 10mg/ 10mg gastro-resistant tablets. Alliance Pharmaceuticals Ltd. Revised December 2019.

US National Library of Medicine. Toxicology Data Network. Drugs and Lactation Database (LactMed).
Doxylamine Available at: https://toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen?LACT
Last revised: 04 June 2018
Last accessed: 29 August 2018