464104
2012
TPP312045125312464104Therapeutic Advances in PsychopharmacologyL. Paklet, A Abe
Therapeutic Advances in Psychopharmacology
Original Research
Priapism associated with risperidone: a
case report, literature review and review
of the South London and Maudsley hospital
patients’ database
Ther Adv Psychopharmacol
(2013) 3(1) 3–13
DOI: 10.1177/
2045125312464104
© The Author(s), 2012.
Reprints and permissions:
http://www.sagepub.co.uk/
journalsPermissions.nav
Lise Paklet, Anne Mary Abe and Dele Olajide
Abstract: Priapism is a urological emergency defined as persistent penile erection that
is unrelated to sexual stimulation and typically involving only the corporal cavernosa. It
can occur as a rare side effect of antipsychotic medications and is mediated via their αadrenergic antagonist effect. In this paper we describe a case of priapism in a patient started
on risperidone and sodium valproate. We also review the South London and Maudsley Case
Register Interactive Search database to assess how many other cases of priapism were
reported in patients taking risperidone. We add this information to a literature review of cases
of priapism associated with risperidone.
Keywords: Antipsychotics, priapism, risperidone, sexual side effects
Introduction
Priapism is a urological emergency defined as
persistent penile erection that is unrelated to sexual stimulation [Huang et al. 2009]. It typically
involves the corporal cavernosa [Keoghane et al.
2002]. It can occur as a rare side effect of antipsychotic medications and is thought to be mediated
via their α-adrenergic antagonist effect [Spagnul
et al. 2011; Andersohn et al. 2010].
In this paper we describe a case of priapism in a
patient recently started on risperidone and sodium
valproate. We also review the South London and
Maudsley (SLAM) Case Register Interactive
Search (CRIS) database to assess how many other
cases of priapism were reported in patients taking
risperidone. We add this information to a literature review of cases of priapism associated with
risperidone, building on the work of Choua and
colleagues and Sood and colleagues [Choua et al.
2007; Sood et al. 2008].
Delayed recognition of priapism can have irreversible consequences with up to 50% of affected
patients becoming impotent [Choua et al. 2007;
Sood et al. 2008] or in some cases needing penile
amputation [Hoffman et al. 2010] often because
http://tpp.sagepub.com
they present late. We believe that clinicians reviewing patients for sexual side effects, recognizing
priapism and educating patients on how to distinguish priapism from a normal erection can minimize poor outcomes.
Correspondence to:
Anne Mary Abe, MBBS,
MRCPsych
Neuroscience Department,
Institute of Psychiatry,
Kings College London, De
Crespigny Park, London
SE5 8AF, UK
Anne-Marie.Abe@kcl.
ac.uk
Case report
Y is a 45-year-old African with a 7-year history of
schizoaffective disorder. Since his initial diagnosis, he had never been completely symptom free
and poor compliance with medication had led to
several relapses, hospital admissions and medication changes. He had previously been on various
antipsychotics, including olanzapine, haloperidol,
flupenthixol depot and trifluoperazine in combination with sodium valproate.
Lise Paklet, MBBS, BSc
St Charles Hospital,
London
Dele Olajide, PhD, FRCPsych
South London and
Maudsley NHS Foundation
Trust, London, UK
His last admission took place at the end of 2010
following concerns that he had stopped his medication (trifluoperazine and sodium valproate) and
that his mental state was deteriorating. He was
showing signs of self-neglect, fluctuating mood,
agitation and irritability. He expressed grandiose
delusions, paranoid ideations and had limited
insight into his condition. He was started on risperidone 2 mg at night and sodium valproate 750
3
Therapeutic Advances in Psychopharmacology 3 (1)
mg twice daily. One week later, risperidone was
increased to 4 mg at night and sodium valproate
to 1000 mg twice daily.
Y reported a 48 h history of persistent and painful erection 3 days later. He was immediately
sent to the emergency department where a diagnosis of low flow priapism was made. He was
treated with ice, pain relief and aspiration of
220 ml of blood from the corpora cavernosa
and intracorporal injection of adrenaline.
Risperidone was stopped immediately. He
improved only slightly on this treatment, and
was referred to the andrology department for
shunting, which was performed the next day. A
subsequent magnetic resonance imaging scan
showed significant penile ischaemia, which
required surgery and the insertion of a penile
implant 7 days later. After a medication-free
period, risperidone was replaced with aripiprazole. He tolerated this well and was discharged
from hospital. He reported no further episodes
of priapism after discharge.
On further questioning, Y admitted to one previous episode of priapism, which had occurred 3
days earlier and resolved spontaneously after 2 h.
He denied any prior experience of priapism or
any other erectile dysfunction. Apart from taking
antipsychotic medication, he had no risk factors
for priapism. He tested negative for sickle cell disease or trait and did not have any haematological
disorder. He had never taken drugs for erectile
dysfunction and had no history of illegal substance use such as cocaine or cannabis. He had no
past or current medical history of note and was
not on any medication with the exception of
sodium valproate and risperidone. At home, he
drank alcohol most days (beer) but rarely
exceeded 2 units a day. He was a nonsmoker and
had never had pelvic or genital trauma. Family
history was unremarkable and he denied any drug
allergy. Written informed consent was obtained
from Y for this publication.
Pathology
In physiological erection, relaxation of the two
corpora cavernosa allows increased arterial blood
flow into the penis. This causes pressure on the
veins that normally drain the penis, reducing
venous outflow. The two mechanisms combine to
cause a temporary engorgement of blood in the
penis and erection. Reversal of this process causes
detumescence. Several neurotransmitters have
4
been implicated in the regulation of this complex
process both centrally and peripherally. At the
level of the peripheral nervous system, relaxation
of the penile muscles is mediated mostly by the
parasympathetic system (via acetylcholine muscarinic receptors) and the release of nitric oxide
from the endothelium of the bloods vessels that
line the corpora cavernosa. Detumescence and
flaccidity are mediated by the sympathetic system, which releases noradrenaline acting on
α-adrenergic receptors to cause contraction of
the penile vessels and smooth muscles, which in
turn reduces blood flow into the penis [Andersohn
et al. 2010; Andersson, 2001]. Two types of priapism have been identified: low flow (ischaemic)
and high flow (nonischaemic). In low-flow priapism, there is prolonged failure of venous outflow, typically either because the draining veins
become obstructed (for instance in sickle cell or
other haematological disorders) or because the
sympathetic system fails to initiate detumescence. Blood stasis leads to ischaemia and fibrosis if left untreated. High-flow priapism results
from excessive unregulated flow of arterial blood
into the penis without outflow obstruction. The
corpora cavernosa remain well supplied with
oxygenated blood and penile tissues remain
undamaged.
Low-flow priapism is a urological emergency. In
adults it occurs most frequently in men in their
third and fourth decade. The most common risk
factors are pharmacological in adults and haematological disorders in children (although in 40–
50% of all cases no cause is found) [Oweis, 2001;
Sharma and Fleisher, 2009; Sood et al. 2008].
Several drugs have been associated with priapism. Some drugs commonly used in the management of cardiovascular and urological
symptoms like prazosin, tamsulosin and doxazosin are α-adrenergic receptor antagonists
[Spagnul et al. 2011]. Priapism is also a documented side effect of trazadone, an antidepressant with α-adrenergic antagonist properties
[Abber et al. 1987]. Anticoagulant medication,
including warfarin and intravenous heparin,
some antihypertensives such as nifedipine, β
blockers such as labetalol, corticosteroids, oral
hypoglycaemic agents (tolbutamide) and other
conditions such as pelvic trauma and pelvic
tumours which may be associated with hyperviscosity states such as various haematological disorders and metabolic disorders (e.g. amyloidosis)
can increase the risk of priapism [Brichart et al.
2008; Lapan et al. 1980].
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L. Paklet, A Abe et al.
Literature review
It is estimated that between 15% and 26% of priapism cases are linked to the use of antipsychotic
medication [Sharma and Fleisher, 2009], via α1and α2-antagonist activity, which inhibits sympathetic activity [Andersohn et al. 2010; Sood et al.
2008]. It has also recently been proposed that the
corpora cavernosa of some men may be more sensitive to the α-blocking effect of antipsychotic
medication [Sharma and Fleisher, 2009].
Although, atypical antipsychotics were initially
thought to be less likely to cause priapism than
their typical counterparts, all have now been
associated with this side effect, including risperidone, olanzapine, aripiprazole, clozapine and
quetiapine. Choua and colleagues did a literature
search on PubMed/Medline (from 1994 to the
third week of February 2007) and found 17
reported cases of priapism associated with risperidone, 11 with olanzapine (penile priapism
only), 5 associated with quetiapine, 3 with
ziprasidone and 2 with aripiprazole (both in
monotherapy and in combination with other
medications) [Choua et al. 2007].
In 2008 Sood and colleagues found 50 reports of
priapism associated with atypical antipsychotics
up to 2007, out of which 16 were associated with
risperidone [Sood et al. 2008]. Building on this
work, we searched PubMed and Ovid until 2011
with no time or language restrictions and found
an additional 16 case reports of priapism involving risperidone (Table 1).
We also reviewed the data of 180,000 patients
treated at SLAM using the CRIS database, which
was developed by the Biomedical Research
Council (BRC) for use by researchers allowing
anonymised access to information from SLAM’s
electronic patient records. BRC monitors the use
of the CRIS database and patients are able to opt
out of the CRIS database if they choose.
We found 13 cases of reported priapism between
2000 and 2010, 6 in patients taking risperidone
(3 as monotherapy and 3 in combination with
other drugs). Five cases were associated with trazodone, 1 with paroxetine, 1 with clozapine and
citalopram (Table 2).
In the UK, 37 cases of priapism in patients taking
risperidone have been reported so far to the
Medicines and Healthcare Products Regulatory
Agency since the drug was licensed in 1992
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(including the case described in this paper), with
a total number of 7961 reactions reported in
patients on risperidone.
It is difficult to draw a typical risk profile from
these findings. However, it seems priapism can
occur at any time from a few days following initiation of treatment up to 2 years. The age of those
affected ranged from 13 to 65, although in a
majority of cases, patients were in their 30s, 40s
and 50s. The most striking feature of this review
is the ethnic background of the patients. Out of
32 cases described in the literature, the ethnic
group was known for 14 patients, 8 of which were
of African-Caribbean origin, 4 were Hispanic.
Out of the six cases identified at SLAM, four were
of African-Caribbean origin, a population group
more likely to be on antipsychotic medication
[Bresnahan et al. 2007; Fearon et al. 2006;
Kirkbride et al. 2006; Xanthos, 2008]. It is also
worth noting that SLAM serves a migrant multiethnic catchment area, with a significant black
African–Caribbean population, which undoubtedly contributes to this community being over
represented in our small sample. We are not aware
from our literature review of any described genetic
predisposition in the black population with the
exception of sickle cell disease, which is the most
common cause in children [Adeyoju et al. 2002]
and to a lesser extent sickle cell trait [Adeyoju et al.
2002; Birnbaum and Pinzone, 2008; Larocque
and Cosgrove, 1974]. Unfortunately not all published case reports report whether sickle cell disease or trait was present.
Among atypical antipsychotics, risperidone and
ziprasidone have the highest affinity for
α-adrenergic receptors [Andersohn et al. 2010]
and have been associated with several cases of
priapism, both when administered as a monotherapy or in combination with other drugs [Brichart
et al. 2008; Sood et al. 2008]. α-Adrenergic receptors have a significant role in physiologic erectile
function and classes of drugs with α-adrenergic
antagonistic properties can cause priapism
[Horowitz and Goble, 1979; Traish et al. 2000]
by inhibiting the process that causes penile detumescence [Spagnul et al. 2011]. It is unclear from
the research published so far whether and to what
extent the combination of different risk factors or
polypharmacy increases the risk of priapism
[Birnbaum and Pinzone, 2008].
In theory, polypharmacy may increase the risk of
priapism either through the synergy achieved by
5
Therapeutic Advances in Psychopharmacology 3 (1)
Table 1. Literature review.
Study
Age, ethnic
background
Treatment with
risperidone
Other
medications
Priapism history
Ankem et al.
[2002]
Bourgeois
and Mundh
[2003]
47 African
American
26 Hispanic
4 mg for 2 years
Nil
3 mg for 1 year
Semi-sodium
valproate 1500
mg (1 year)
Retrograde ejaculation
on thioridazine
No previous history of
priapism
Du Toit et al.
[2004]
44 Ethnic
background
unknown
50 Ethnic
background
unknown
29 Congo
8 mg for 2 years
Trazadone 150
mg
10 mg for 12
weeks
3 mg for 6
months
Lithium 1200
mg, lorazepam
1 mg
Citalopram 40
mg
Madhusoodan
et al. [2002]
65 Hispanic
1 mg for 6 weeks
Nil
Makesar and
Thome [2007]
31 Ethnic
background
unknown
4 mg daily for 1
year
16 mg single
dose
Nil
Nicloson
and Mcurley
[1997]
46 Ethnic
background
unknown
8 mg for 7 weeks
Lorazepam 4
mg
Owley et al.
[2001]
17 Ethnic
background
unknown
1.5 mg for 2
years
Lithium 900 mg
Reeves and
Mack [2002]
22 African
American
4 mg for 6
months (on
different dose
for 5 years in
total)
Clonazepam,
vitamin E and
multivitamin
infusion
Relan et al.
[2003]
32 Ethnic
background
unknown
5 mg for 2
months
Nil
Emes and
Millson [1994]
Freudenreich
[2002]
6
Outcome
Other
stated risk
factors for
priapism
Unable to
reach erection
at 10-week
follow up
Priapism on quetiapine
as well
No priapism on
risperidone alone;
priapism developed
4 weeks after adding
citalopram
Switched from
haldol to risperidone
after developing
extrapyramidal side
effects
Priapism occurred 24 h
after taking the 16 mg
dose
Drainage
ineffective;
surgery, loss
of erectile
function
Priapism on 4 mg
risperidone which
resolved on 2 mg but
occurred again on 3 mg
No priapism on
risperidone alone.
Priapism started within
12 weeks of starting
lithium
Had been on variable
doses of risperidone for
5 years and on 4 mg for
6 months before onset
of priapism
Also developed
priapism on ziprasidone
Was on flupentixol for 5
years changed because
of extrapyramidal side
effects
Commenced on
risperidone increased
to 5 mg over 2 months,
developed priapism 2
weeks later.
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L. Paklet, A Abe et al.
Table 1. (Continued)
Study
Age, ethnic
background
Treatment with
risperidone
Other
medications
Priapism history
Slauson and
Lo Vecchio
[2004]
28 Ethnic
background
unknown
Unknown dose
for 4 days
Venlafaxine
Tekell et al.
[1995]
41 Hispanic
6 mg for 6 days
Nil
Wang et al.
[2006]
37 Ethnic
background
unknown
2 mg twice daily
for 9 months
Nil
Risperidone
discontinued after a
first episode of priapism
that self-resolved;
occurred again 4 days
after restarting it
History of retrograde
ejaculation on
thioridazine
Developed priapism
9 months after starting
risperidone
27 Ethnic
background
unknown
37.5 mg
risperidal
for 3 weeks
(previously
was on oral
risperidone 6 mg
daily)
Nil
Yang and Tsai
[2004]
13 Ethnic
background
unknown
2 mg for
4 months
Paroxetine
20 mg
Brichart et al.
[2008]
26 Ethnic
background
unknown
55 Ethnic
background
unknown
23 Hispanic
4 mg, duration
unknown
Unknown
No priapism on oral
risperidone; priapism
started 3 weeks after
starting depot risperidal;
several episodes
resolved spontaneously
after 5 h; on day 27
presented to ED with
priapism lasting 6 h
No priapism on
risperidone initially;
paroxetine was added
after 4 months;
priapism developed
2 months later
1 week duration
2 mg for several
years
Unknown
36 h duration
1 mg at night
Sertraline
150 mg daily
49 Ethnic
background
unknown
Risperidal
Consta, (Janssen
Pharmaceuticals,
New Jersey,
USA), dose not
stated
None
3 episodes of painful
erection at home and 1 in
the ED; further episodes
of priapism after
cessation of risperidone
(on olanzapine +
sertraline and quetiapine
+ sertraline and on
quetiapine alone)
16 h history of priapism
a week after third dose;
3 more episodes over
following 7 days
Brichart et al.
[2008]
Choua et al.
[2007]
Dodds et al.
[2011]
Outcome
Other
stated risk
factors for
priapism
Risperidone
switched to
clozapine 100
mg; no further
episodes reported
No invasive
treatment
required
No further
episodes on
clozapine
No treatment
Hypertrigly
ceridaemia
Aspiration
of corpora
cavernosa,
injection of
phenylephrine;
switched to
fluphenazine
and no further
episodes in
an 18-month
follow up
(Continued)
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7
Therapeutic Advances in Psychopharmacology 3 (1)
Table 1. (Continued)
8
Study
Age, ethnic
background
Treatment with
risperidone
Other
medications
Priapism history
Outcome
Other
stated risk
factors for
priapism
Haberfellner
[2007]
22 White
4 mg risperidone
Sertraline 50
mg
Surgical
intervention
Hosseini et al.
[2006]
24 Ethnic
background
unknown
2 mg daily
increased to
6 mg
Trihexyphenidyl
2 mg
Kirshner and
Davis [2006]
50
Vietnamese
Started
risperidone
3 mg daily +
risperidone 25
mg fortnightly
Koirala et al.
[2009]
Middle age
African
American
Winter shunt;
penectomy 7
weeks later
Alcohol
Cocaine
Koirala et al.
[2009]
14 African
American
In the process
of being
switched from
risperidone oral
to risperidone
depot
1 mg, duration
unknown
Started when sertraline
was added; reports
previous history
of 3 episodes of
priapism when he
took risperidone and
sertraline for 1 month
Episodes of priapism
started on 6 mg
risperidone, continued
on dose reduction;
presented with painful
erection of 6 h duration
at 45 days; switched to
olanzapine 2.5 mg; had
one further episode
of 14 h duration and
olanzapine was also
discontinued
Was on risperidone
6 mg then changed
to 3 mg daily and
risperidone depot
25 mg fortnightly;
priapism resolved when
oral risperidone was
stopped
7-day history of
priapism; resolved
after discontinuing
risperidone
2 weeks of intermittent
erections
Corporeal
aspiration with
phenyephrine
injection;
winter shunt
followed
by T shunt;
recovered
erectile
function
Recurrent
sickle cell
crisis
Knee pain
Maizel et al.
[1996]
Oweis [2001]
44 Jewish
Unknown dose
21 Ethnic
background
unknown
4 mg daily for 10
weeks increased
to 8 mg 6 days
prior to onset of
symptoms
Relieved with
intravenous
diazepam
Surgical
intervention
No other
medication
2 months of intermittent
episodes lasting
between 1 and 3 h;
presented with 20 h
duration of priapism
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L. Paklet, A Abe et al.
Table 1. (Continued)
Study
Age, ethnic
background
Treatment with
risperidone
Other
medications
Priapism history
Penaskovic
et al. [2010]
21 African
American
Dose unknown
No other
medication
Rosenberg
et al. [2009]
49 Ethnic
background
unknown
Risperidone 8
mg
Lithium 300 mg
in morning, 600
mg at night
Salawu et al.
[2010]
30 Nigerian
4 mg daily
Sertraline 50
mg daily
Priapism in 2007 on
risperidone; further
episode in 2009
when olanzapine
was increased to 15
mg four times a day;
subsequently started
on quetiapine 25 mg
four times a day and
had further episode of
priapism 2/7 later
2 days after admission
on prescribed dose;
recurrence on
aripiprazole and lithium,
stopped when lithium
was stopped; followed
up for 3 months
3 episodes on sertraline
alone; no priapism
on risperidone alone;
2 episodes on both
medications
Sharma and
Fleisher
[2009]
Sirota and
Bogdanov
[2000]
Yen-Yue et al.
[2007]
31 African
American
2 mg morning 3
mg at night
Nil
19 Askenazi
Jew
2 mg daily
26 Ethnic
background
unknown
3 mg daily for 3
years
Other
stated risk
factors for
priapism
Cannabis
Cocaine
Alcohol,
Hepatitis C
virus
Cannabis
use
No longlasting erectile
dysfunction
Phenylephrine;
winter shunt
3 episodes on day 6 of
risperidone
Started Gingko
biloba 160 mg
daily 2 weeks
prior to onset
of symptoms
Outcome
Sickle cell
trait
Urological
intervention
4 h episode
Table initially developed by Sood et al. [2008] (the first 16 cases listed above are those originally described by Sood et al. [2008]).
ED, emergency department. 2/7, 2 days.
combining drugs that independently can cause
priapism or by combining drugs like risperidone
with another drug that affects its metabolism.
The effect of sodium valproate on liver enzymes is
complex and not yet fully understood. According
to the Clinical Manual of Drug Interaction Principles
for Medical Practice [Wynn et al. 2009], sodium
valproate inhibits 2D6, 2C9, 1A4, 1A9, 2B7,
2B15, UGT and epoxide hydrolase. There is no
known and proven enzyme induction, although
some evidence suggests that sodium valproate
may induce 3A4 and ABCB1. Risperidone is
metabolized by the cytochrome P450 2D6
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enzymatic system and to a lesser extent 3A4
[Prior and Baker, 2003], so there is a possibility
that enzyme inducers or inhibitors could have an
impact on risperidone plasma levels [Bork et al.
1999; Odou et al. 2000; Yen-Yue et al. 2007],
suggesting an increased risk of adverse side effects
with coadministration of such drugs with risperidone. However, other studies suggest that valproate does not affect risperidone levels. A study
by Spina and colleagues compared 10 patients
taking sodium valproate and risperidone with 23
patients taking risperidone alone and found no
significant difference in the levels of risperidone
9
Therapeutic Advances in Psychopharmacology 3 (1)
Table 2. South London and Maudsley patients review.
10
Age, ethnic
background
Antipsychotic
medications
Other
medications
Priapism history
Other relevant
information
including risk
factors for
priapism
45 AfroCaribbean
Risperidone 4 mg
Sodium
valproate
1000 mg
twice daily
No other risk
factors for
priapism
40 AfroCaribbean
Nil
38 White
European
Risperidone 1
mg twice daily
Carbamazepine
100 mg once a day
Risperidone 2 mg
daily
2 episodes reported; the
first started 7 days after
initiation of treatment with
risperidone, resolving
spontaneously; the second
episode occurred 10 days
later and led to penile
amputation
Priapism resolved when
risperidone was reduced to 1
mg daily
Type 1 diabetes
mellitus
Cannabis use
39 AfroCaribbean
36 Unknown
ethnic group
41 AfroCaribbean
Risperidone 3 mg
at night
Risperidal Consta
50 mg
Risperidal Consta
25 mg
Multiple episodes of selfresolving priapism after
starting risperidone; these
resolved upon cessation
Not described
Insulin
Carbimazole
Unknown
Lithium 1000
mg
Priapism resolved when dose
was reduced to 25 mg
Not described
Hyperthyroidism
Hypertension
Cannabis
Sickle cell trait
and its metabolite, 9-hydroxyrisperidone [Baxter,
2012; Spina et al. 2000]. Yoshimura and colleagues looked at 12 patients with schizophrenia
given valproic acid 400–800 mg daily and risperidone 2–6 mg daily and came to the same conclusion [Baxter, 2012; Yoshimura et al. 2007]. It is
currently accepted that no special precautions
should be taken when prescribing risperidone and
sodium valproate together [Baxter, 2012]. We
have found no cases reporting priapism associated with sodium valproate.
of ischaemia, anaerobic metabolism, acidosis and
long-term penile tissue injury and fibrosis [Lapan
et al. 1980]. Penile ischaemia following priapism
could eventually result in penile amputation
[Hoffman et al. 2010]. Early presentation therefore gives the best chance to improve outcome.
There may be other types of drug interactions that
can increase the risk of priapism. Lithium is not
directly associated with priapism, however a number of cases have occurred in patients taking lithium and risperidone concurrently. A suggested
mechanism of action is that lithium potentiates
the α-adrenergic blocking activity of risperidone
[Jagadheesan et al. 2004; Owley et al. 2001]. A
review of published case reports shows that despite
being extremely painful and worrying for patients;
priapism is often reported late, possibly because
the patient is embarrassed and hoping that the
erection will settle spontaneously. However, the
longer the duration of priapism, the higher the risk
(1) Therapeutic aspiration (with or without
irrigation).
(2) Intracavernous injection of sympathomimetics (e.g. phenylephrine, epinephrine,
norepinephrine, metaraminol).
(3) Systemic treatment of underlying disease
(e.g. sickle cell disease) plus intracavernous
treatment for patients with underlying disorders or haematologic pathology.
(4) Surgical shunts, including distal shunts
(e.g. Winter, Ebbehoj and Al-Ghorab procedures); the cavernospongious shunt (i.e.
Quackels procedure); and cavernosaphenous shunt (i.e. Grayhack procedure).
Priapism should be treated as an emergency. The
American Urological Association recommends the
following treatment guidelines [Erectile Dysfunction
Guideline Update Panel, 2003]
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L. Paklet, A Abe et al.
Conclusion
Antipsychotics, in particular α-adrenergic receptor
antagonists like risperidone, may cause priapism.
Although a rare side effect, it may have devastating
consequences if not treated promptly.This highlights
the need for increased awareness to facilitate early
recognition and treatment. Special care must be
taken when prescribing risperidone in patients
potentially more susceptible to this side effect, such
as those with comorbid pathology (i.e. sickle cell disease) or when treatment might also increase their
risk [Brichart et al. 2008; Lapan et al. 1980]. Patients
should be educated on distinguishing priapism from
a normal erection and the need to report priapism
promptly if it occurs should be emphasized, especially in at-risk patients. We could not find any studies that looked at alternative antipsychotic prescribing
for patients who are at high risk of priapism, however
given that drugs with high α-adrenergic antagonistic
properties seem to increase the risk, antipsychotics
with lower α-adrenergic affinity would be the preferred choice of treatment. It is unclear from the evidence whether priapism is idiosyncratic or a
dose-related event. The literature review does suggest that some patients seemed to develop priapism
only after an increase in medication dose (Table 1).
Overall our review shows that the aetiopathogenesis is far from being fully understood. We anticipate, with future advances in research, that
physicians will be better able to identify patients
who are at higher risk.
Acknowledgements
We would like to thank Olubanke Olofinjana, our
team pharmacist at the South London and
Maudsley NHS Foundation trust for her invaluable guidance and advice.
Funding
This research received no specific grant from any
funding agency in the public, commercial, or notfor-profit sectors.
Conflict of interest statement
The authors declare no conflicts of interest in
preparing this article.
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