Phenothiazines - Uses and Benefits

Type of Drug

Drugs for nausea and vomiting.

How the Drug Works

Drug-induced vomiting (including drugs, radiation, metabolic disorders) is generally stimulated through the chemoreceptor trigger zone (CTZ), which in turn stimulates the vomiting center (VC) in the brain. Nausea from motion sickness is initiated by stimulation of a mechanism of the ear, which sends impulses to the CTZ. The VC may also be stimulated directly (by stomach irritation, motion sickness, etc).

These drugs act on the CTZ, VC, nerve pathways and other centers of the brain to reduce nausea and vomiting.

Uses

To control nausea and vomiting.

Chlorpromazine, Perphenazine - To relieve hiccups. Promethazine - To treat and prevent motion sickness.

Precautions

Sensitivity to light: Rare instances of skin pigmentation have occurred, primarily in females on long-term, high dose therapy. These changes, restricted to exposed areas of the skin, range from almost imperceptible darkening to a slate gray color, sometimes with a violet hue. Pigmentation may fade following drug discontinuation. These effects occur most commonly with chlorpromazine.

May cause photosensitivity. Avoid prolonged exposure to the sun and other ultraviolet light. Use sunscreens and wear protective clothing until tolerance is determined.

Neuroleptic Malignant Syndrome (NMS) : NMS is a potentially fatal syndrome associated with phenothiazines. Symptoms include: Increased body heat; muscle rigidity; altered mental abilities, including catatonia; irregular pulse and blood pressure; increased heart rate; spoonbill; and irregular heart rhythm. in the elderly, especially women. The risk of developing these involuntary movements and the likelihood they will become permanent are increased with long-term use and with high doses. However, it is possible to develop these symptoms after short-term treatment at low doses. The syndrome is characterized by rhythmical involuntary movements of tongue, face, mouth, or jaw (eg, protrusion of tongue, puffing of cheeks, puckering of mouth, chewing movements), sometimes accompanied by involuntary movements of the arms and legs. Fine worm-like movement of the tongue may be an early sign of the syndrome. If the medication is stopped at this time, the syndrome may not develop. There is no known treatment for established cases of tardive dyskinesia, although the syndrome may stop, partially or completely, if the drug is withdrawn.

Pregnancy: Safety for use during pregnancy has not been established. Use only when clearly needed and potential benefits outweigh the possible hazards to the fetus.

Thiethylperazine - Do not use during pregnancy. The risk of use in a pregnant woman clearly outweighs any possible benefit.

Breastfeeding: Chlorpromazine appears in breast milk. It is not known if other phenothiazines appear in breast milk. Consult your doctor before you begin breastfeeding.

Children: In general, these products are not recommended for children younger than 12 years of age. Children with acute illnesses (eg, chickenpox, CNS infections, stomach or intestinal irritation, measles) or dehydration appear much more susceptible to neuromuscular reactions than adults. Symptoms can occur and may be confused with the signs of an undiagnosed primary disease responsible for vomiting (eg, Reye syndrome). Avoid these agents in children and adolescents whose signs and symptoms suggest Reye syndrome.

Prochlorperazine, promethazine - Not recommended for children under 20 pounds or younger than 2 years of age. Not for use in pediatric surgery. Children seem more prone to develop reactions, even on moderate doses. Use the lowest effective dose. Occasionally, the patient may react to the drug with signs of restlessness and excitement; if this occurs, do not administer additional doses. Use with caution in children with acute illnesses or dehydration. Not for use in conditions for which children's dosages are not established.

Elderly: Low doses are usually sufficient for elderly patients. These patients are more susceptible to lowered blood pressure and other side effects. Doses should be increased gradually.

Lab Tests: Lab tests may be required to monitor treatment. Be sure to keep appointments. Tests may include blood counts and kidney and liver function.

Tartrazine: Some of these products may contain the dye tartrazine (FD&C Yellow No.5), which can cause allergic reactions in certain individuals. Chock package label when available or consult your doctor or pharmncist.

Drug Interactions

Tell your doctor or pharmacist if you are taking or if you are planning to take any over-the-counter or prescription medications or dietary supplements with phenothiazines. Doses of one or both drugs may need to be modified or a different drug may need to be prescribed. The following drugs and drug classes interact with phenothiazines.

ACE inhibitors (eg, lisinopril)
Alcohol guanethidine (eg, ismelin)
Epinephrine (eg, Adrenalin)
Biperiden (Akineton)
Carbamazepine (eg, Tagretol)

Side Effects

Every drug is capable of producing side effects. Many phenothiazine users experience no, or minor, side effects. The frequency and severity of side effects depend on many factors including dose, duration of therapy and individual susceptibility. Possible side effects include:

Liver: Yellowing of skin and eyes (jaundice); abnormal liver function tests. Parkinson Disease-Like Symptoms: Tremors; drooling; muscle rigidity restlessness; unusual eye movements; shuffling walk.

Muscular System : Muscle spasms including neck and back muscles; abnormal eye movements; aching and numbness of legs and arms; discoloration; rounding of the tongue; tightness in throat; difficulty swallowing; involuntary movement of tongue, face, mouth or jaw (protrusion of tongue, puffing cheeks, puckering of mouth, chewing movements); weakness; muscular deformation; inability to sit still; fixed eyeballs; exaggerated reflexes; difficulty moving; clumsiness; slurred speech; involuntary movements of arms and legs; agitation; jitteriness.

Circulatory System: Changes in blood pressure; postural hypotension (lightheadedness when rising quickly from a sitting or lying position); ECG changes; cardiac arrest; rapid heartbeat; irregular heart rhythm; change in pulse rate.

Psychiatric: Catatonia; phobia; tiredness; restlessness; hyperactivity; confusion; nightmares; depression; excitement; bizarre dreams; sleeplessness.

Skin: Hives; rash; swelling; redness; itching; sensitivity to light; skin pig mentation; pallor; flushing; sweating; oily skin.

Urinary and Reproductive Tract: Appearance of milk and breast engorgement and aching in women; breast enlargement in men; menstrual irregularities; changes in sex drive; changes in blood sugar levels; infertility and false pregnancy; inhibition of ejaculation.

Eyes or Ocular: Glaucoma; sensitivity to light; blurred vision; changes in pupil size; problems with lens, retina and cornea.

Respiratory System: Tightness of throat in muscular system; nasal congestion; difficulty breathing; asthma.

Digestive Tract: Changes in appetite; nausea; vomiting; constipation; diarrhea, stomach upset; sore throat.

Other: Abnormal blood counts; urinary retention; increased urination; painful erections; impotence (male); swollen glands; thirst; pink or reddish brown urine; dry mouth and nose; ringing in the ears; kidney failure, acute; fever; salivation; sugar in the urine; weight change; swelling of arms, legs and face; urinary retention; inability to control urination; angioneurotic edema; death; swelling of arms, hands and face.

Guidelines for Use

Brand interchange - Do not change from one brand of this drug to another without consulting your pharmacist or doctor.
Do not stop taking this medicine without checking with your doctor.
Oral agents may be ineffective if expelled after vomiting has already begun. Use of suppositories or injection should be considered under such circumstances.
Take these drugs routinely as directed. They control illness symptoms. They are not addicting.
May cause drowsiness. Use caution while driving or performing other tasks requiring alertness, coordination, or dexterity.
Avoid alcohol or other drugs that cause drowsiness.
Sensitivity to sunlight - May cause photosensitivity (sensitivity to sunlight). Avoid prolonged exposure to the sun and other ultraviolet light. Use sunscreens and wear protective clothing until tolerance is determined.
May discolor the urine pink or reddish-brown. This is not harmful.
If dizziness or fainting occurs, avoid sudden changes in posture and use caution when climbing stairs, etc. (more common during first week of therapy).
Use caution in hot weather. These drugs may increase susceptibility to heat stroke.
Notify your doctor if sore throat, fever, unusual bleeding or bruising, skin rash, weakness, tremors, impaired vision, dark-colored urine, pale stools, jaundice, or involuntary muscle twitching occurs.
May cause photosensitivity. Avoid prolonged exposure to the sun or other forms of ultraviolet (UV) light (eg, tanning beds). Use sunscreens and wear protective clothing until tolerance is determined.
Lab tests may be required to monitor treatment. Be sure to keep appointment. tests may include blood and counts and kidney and liver function.
Liquid concentrates are light sensitive. They are usually dispensed in amber or opaque bottles and protected from light. These solutions are most conveniently administered by dilution in fruit juices or other liquids. Shake well. Use these solutions immediately after dilution.
Liquid concentrates - Avoid contact with skin (contact dermatitis may occur). Store at room temperature (59° to 86°F). Protect from light.
Chlorpromazine-
Sustained release capsules: Do not crush or chew. Swallow whole.
Perrthenazine -Concentrate: Dilute only with water, saline, SevenUp, homogenized milk, carbonated orange drink and pineapple, apricot, prune, orange, V-8, tomato, and grapefruit juices. Do NOT mix with beverages containing caffeine (coffee, cola), tannins (tea), or pectinates (apple juice). Use approximately 60 mL (2 oz) liquid for each 16 mg (5 mL or 1 tsp) concentrate. Store tablets and concentrate at controlled room temperature.
All dosage forms should be stored between 59° and 77°F. Refrigerate promethazine suppositories between 36° and 46°F.

CENTRAL NERVOUS SYSTEM AGENTS

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