Synarel (Nafarelin) is made by Searle. It is a strong artificial form of the natural female hormone Gonadotrophin Releasing Hormone (GnRH).

How Synarel works

During the continuous use of Synarel (over three to four weeks) the Follicle Stimulating Hormone (FSH) and Leutinising Hormone (LH) produced by the pituitary gland (at the base of the brain) are decreased. As a result, the ovaries do not function properly and the production of oestrogen and progesterone is reduced. This tricks the body into a pseudo (false) menopause and causes the shrinking of the deposits of endometriosis.

Periods usually stop during treatment but generally return in two to three months of treatment ending.

Administration and dosage of Synarel

Synarel comes as a solution in a bottle with a metered spray pump. This delivers 200mcgs of Synarel per spray.
Synarel is taken twice daily as one spray to one nostril in the morning, and one spray to the other nostril in the evening, giving a total dose of 400mcgs a day.
Treatment should be started between day two and day four of the menstrual cycle. Day one of the cycle is the first day of bleeding.
The recommended course of treatment is six months.
The spray is absorbed through the lining of the nose even if you have a cold. In these circumstances blow the nose thoroughly before using the spray. If decongestants are used for the treatment of a cold, the decongestant should be used at least thirty minutes after using the Synarel spray.

Synarel is not suitable for the treatment of children.

When Synarel should not be used (contra-indications)

  • Pregnancy
  • Lactating women (breast feeding)
  • Undiagnosed vaginal bleeding
  • Allergy (sensitivity) to GnRH Analogues or other ingredients used for the solution to dissolve the drug
  • Repeat treatment, or treatment longer than six months, as it takes about six months for bone density to recover

Precautions in the use of Synarel

If a dose is missed and pregnancy occurs, the treatment should be stopped, as there is a potential risk to the foetus.
Women with polycystic ovaries should be closely observed as further cysts may develop in the first two months of treatment.

Reaction of Synarel with food/alcohol/drugs

None have been reported.

Side effects of Synarel

  • Hot flushes
  • Vaginal dryness
  • Emotional changes
  • Muscle cramps
  • Irritation to the nose lining
  • Fluid retention
  • Nausea
  • Depression
  • Changes in sex drive
  • Headaches
  • Acne
  • Decrease in breast size
  • Weight gain
  • Dizziness
  • Hair loss

Very occasionally the following side effects may occur:

  • Shortness of breath
  • Chest pains Skin rashes
  • Pruritus (irritation of the skin around the back passage)

Do remember to report any side effects to your medical practitioner and ask for advice.

Notes on Synarel

  • Make sure that you are not pregnant before starting treatment. A pregnancy test is advisable.
  • Barrier methods of contraception should be used during treatment (until periods restart), as Synarel is not a contraceptive.
  • Some patients have a loss of bone density during treatment with Synarel. This is reversed within about six months of the treatment ending in young patients.
  • In slim patients or those who have other risk factors for osteoporosis a baseline DEXA scan is useful to monitor bone mass before and after treatment. See osteoporosis leaflet for further information.
  • Add-back therapy may be suggested to prevent bone loss.
  • Treatment for three months may be as effective as for six months.
  • Recurrence of symptoms occurs in 40-70% of cases especially with severe disease where endometrial deposits and lesions such as ovarian endometriomas and recto-vaginal nodules occur. Surgical resection of these may be necessary.
  • Periods generally return within two to three months after completion of treatment.
  • It is advisable to have one period before trying for pregnancy.

See also

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