Overview
Doxepin is a tricyclic antidepressant and anxiolytic (anti-anxiety) drug that reduces reuptake of norepinephrine — a neurotransmitter - to bring its levels back to normal. Doxepin is an anticholinergic - a drug that blocks the parasympathetic nerves - and a sedative. It is the only tricyclic antidepressant to relieve itching as well as several types of pain.

Doxepin usually takes effect within two to four weeks, but the time may be longer due to dosage and an individual’s reaction to the drug. Some effects may be felt on the first day.

Why is this drug prescribed?
Doxepin is used to treat several types of depression including:

1. refractory depression
2. major depression
3. mixed depression anxiety
4. neurotic depression
5. spontaneous endogenous depression
6. depression or anxiety due to alcoholism
7. manic-depressive illness.

Doxepin has also been used to treat:

1. anxiety
2. chronic skin disorders
3. itching
4. panic disorders
5. peptic ulcer disease
6. postprandial hypoglycemia
7. posttraumatic stress disorder ( PTSD )
8. sleep disorders
9. cravings of smoking
10. swelling
11. excessive nighttime urination
12. chronic pain associated with: arthritis, diabetic disease, herpes lesions, migraines, pain in cancer patients, tension headaches, or tic douloureux

Warnings and Precautions
Doxepin is not recommended for children under twelve years old because Doxepin’s effects on children have not been adequately studied. Children over twelve years old are recommended the same dosage as adults.

Doxepin can cause photosensitivity and can reduce sweating which impairs the body's ability to adapt to heat. Patients should avoid saunas and other very hot environments.

Doxepin is not addictive. Suddenly discontinuing Doxepin may cause withdrawal symptoms including headache and nausea. Dosages should be gradually tapered to minimize withdrawal.

Doxepin can cause drowsiness and dizziness: a patient taking Doxepin should not drive or operate heavy machinery until he knows that it does not impair his ability do engage in these activities.

For Nursing Mothers: Controlled studies have not been done in pregnant women, but there have been reports of newborns suffering from muscle spasms and heart, breathing, and urinary problems when their mothers had taken tricyclic antidepressants immediately before delivery. Animal studies show that some tricyclic antidepressants may have undesirable effects on a fetus. Tricyclic antidepressants pass into breast milk and are reported to cause drowsiness in nursing infants.

Contraindications
Doxepin should Not be used for people with the following medical conditions:

1. schizophrenia — Doxepin may aggravate the condition
2. liver or kidney disease — patients may need careful monitoring while on Doxepin
3. a recent heart attack
4. narrow-angle glaucoma
5. a history of epilepsy, diabetes, glaucoma, heart / liver disease, an overactive thyroid, or an enlarged prostate gland — Doxepin may still be used in many cases, but with extra caution
6. a history of blood disease

Adverse Reactions
Doxepin may cause the following reactions:

1. drowsiness
2. dizziness
3. insomnia
4. blurred vision
5. rash
6. dry mouth
7. constipation
8. photosensitivity
9. ringing in ears
10. agitation
11. diarrhea
12. high blood pressure
13. hair loss
14. increased or decreased libido
15. nausea
16. sweating
17. swelling
18. weight gain or loss
19. seizures
20. delirium
21. delusions
22. hallucinations
23. Tourette’s syndrome
24. liver / kidney toxicity
25. heart rhythm disturbances
26. abnormally low white blood cell and platelet count
27. tremors
28. nightmares
29. low blood pressure
30. increased appetite
31. racing heartbeat
32. irritation of the tongue or mouth
33. confusion

Interactions with Drugs and Other Substances
Drugs or substances that may interact with Doxepin are:

1. MAO Inhibitors (within 14 days) serious, even fatal, interactions can occur when taken with Doxepin
2. all atropine like drugs, all sedative drugs, antihistamines, norepinephrine, Dilantin (phenytoin), and Coumadin (warfarin) — Doxepin may increase the effects of these
3. Catapres (clonidine), Hylorel (guanadrel), Ismelin / Esimil (guanethidine), Primatene tablets(ephedrine) and Tenex (guanfacine) — Elavil may decrease the effects of these drugs
4. Tagamet (cimetidine), estrogens, Prozac (fluoxetine), Luvox (fluvoxamine), Normodyne (labetalol), Ritalin (methylphenidate), oral contraceptives, phenothiazines, Quinaglute (quinidine), ACE inhibitors, Calan (verapamil), and Zantac (ranitidine) — these drugs may increase the effects of Doxepin
5. Norvir (ritonavir) and other protease inhibitors may lead to drug toxicity when taken with Doxepin
6. Stimulant drugs (such as cocaine, amphetamines, Proventil, sutafed) — these medications can cause severe high blood pressure and/or high fever when taken with Doxepin
7. Thyroid medications can increase the risk of heart rhythm disorders when taken with Doxepin
8. Demerol (meperidine) can cause a lower rate of breathing when taken with Doxepin
9. alcohol — when taken with Doxepin or another TCA can increase the intoxicating effects of alcohol and combination can depress brain function significantly; alcohol should be avoided completely

Sources

http://www.rxlist.com/scripts/patient/piumore.pl?mononum=502&
dc_category=Depression&order=0&type=&item=

http://www.mentalhealth.com/drug/p30-s03.html

http://www.psyweb.com/Drughtm/doxepi.html

http://www.health-center.com/db/PageReq?SessionID=8816&
TopicID=376&PageID=1529&Action=view