Drug induced Urinary Incontinence

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Definition: Involuntary leakage of urine or inability to hold urine in the bladder is referred to as urinary incontinence. 

Types of Urinary incontinence: are of several types. 

a. Stress Incontinence: is due to physiological reflexes such as coughing, laughing,  running, applies pressure to a full bladder.

b. Urge incontinence: is an overactive bladder.  Patient feels the urge to urinate frequently and repeatedly.  Medical conditions like BPH (benign prostate hyperplasia), Multiple sclerosis, stroke, infections, surgeries, all can cause this condition. 

c. Functional incontinence: could be the result of mental or physical disabilities, which impairs a persons ability to use bathroom,  despite of having a healthy urinary system. 

d. Mixed incontinence: consists of more than one type.

Gender based effects: Urinary incontinence is far more common in women than men, because pregnancies, menopause and female urinary tract anatomical structure all add upto the risks.

Men with enlarged prostate and surgery to correct prostate is the major problematic reason in causing urinary incontinence. 

Drugs can cause urinary incontinence by lowering bladder output or by causing an increase in the intravesical pressure. This disrupts the normal pressure relationship between bladder and urethra. Other reasons may also include CNS disturbances etc.

Drugs which cause urinary incontinence:

1.Hydroxy chloroquine: has been recently identified as an agent that causes urinary incontinence. In a report, a 71 year female developed urinary incontinence as an adverse reaction to this drug when taking this medicine for the treatment of her rheumatoid arthritis. Reoccurence of urinary incontinence was seen with the readministration of the drug.

2.Alpha adreadrenergic blockers: drugs like doxazocin, terazosin, tamsulosin etc. depict their mode of action by blocking postsynaptic alpha 1 receptor and causing arterial and venous dilation. It is known that alpha adrenoceptors influence lower urinary tract function by directly affecting smooth muscles and by acting at levels of spinal cord ganglia and nerve terminals. Blocking these receptors will lead to decreased bladder outlet resistance and more incontinence.

In men suffering from BPH, these medications can cause relaxation of muscles in the neck of bladder and can allow the urine to have a more easier flow.

3.Antidepressants: there are number of classes of antidepressants and almost all cause urinary retention and overflow incontinence. Most of the antidepressants act as Norepinephrine or Serotonin reuptake inhibitors. Some at normal therapeutic doses also show actions as that of adrenergic, cholinergic, histaminergic receptor antagonists. These drugs acts as culprits for causing urinary incontinence by affecting the elasticity of the bladder and by preventing it to contract properly or completely. This results in only half of the bladder being emptied. Urine keeps on entering the bladder due to which the bladder overflows and then leaks without a signal.

4.Diuretics: their mechanism of action itself is an increase in the production of urine. Furosemide, spironolactones, thiazide diuretics are some of the examples of diuretic drugs. They increase the urine volume by promoting more urine formation & this puts pressure on the bladder, therefore, increasing the urinary frequency and urgency.

A study revealed that the use of loop diuretics with alpha blockers doubles the urinary incontinence problem vs. alpha blockers when used alone. But no increase was seen when potassium sparing diuretics and thiazides were given with alpha blockers.

5.Calcium channel blockers: decreases contractility of smooth muscles in bladder due to which urine retention increases and this eventually leads to overflow incontinence. 

6.Alpha adrenergic agonists: e.g. Methyldopa or clonidine, these agents contract the neck of bladder and causes urinary retention followed by overflow incontinence. 

7.Sedative hypnotics: all those sleeping pills which relax muscles and cause deep slumber can aggravate the urinary incontinence condition. Examples of such drugs include flurazepam, diazepam, zolpidem etc. These medications slow down the reflexes and the person misses the alert and doesn’t feel the pressure on bladder.  This results in bed wetting and it has been seen that sedatives affect about 10% of the incontinence sufferers. 

8.Narcotic painkillers: opiate analgesics like morphine, codeine, oxycodone can interfere with the ability of bladder to contract fully and can cause increased urine retention which leads to overflow incontinence. Severe cases of constipation are seen with opiates use, constipation desensitizes the bladder and aggravates the urge incontinence conditions. 

9.ACE Inhibitors and Angiotensin receptor blockers: renin – angiotensin system is specifically present in the bladder and urethra. Blocking it will result in both decreased detrusor over activity and urethral sphincter tone, therefore, causing a reduction in urge incontinence and elevation in stress urinary incontinence. ACE inhibitors also cause dry cough which increases stress incontinence as well.

10.Hormone replacement therapy: oral estrogen only or estrogen combination and progesterone pills can worsen stress and urge incontinence. 

11.Antipsychotics: e.g. thiothixene, thioridazine, chlorpromazine,  haloperidol. Some  people experience the condition within few hours of starting the antipsychotic therapy, whereas in some the urinary incontinence appears after weeks of initiating the therapy. Typical antipsychotics act primarily as dopamine antagonists and cause stress urinary incontinence. Other antipsychotics can cause incontinence by alpha adrenergic blockade, cholinergic action or through dopamine blockade on bladder.

12.Decongestants and Anti Histamines: like pseudo ephedrine or diphenhydramine can tighten the urinary sphincters, causing urine retention followed by overflow incontinence. 

Reference:

a. Drug induced urinary incontinence, Drug Aging

b. Urinary incontinence secondary to drugs, Urology.

c. US pharmacist.

d. Web med.

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